Tired of my EVIL RO/DI unit

[frog_toad_99]

Hello,
I can't do it anymore and I need some advice. The waste water generated by my,as well as most, RO/DI units is ridiculous. I have selfishly put aside my concerns because I don't pay for water, I'm certainly an American. It seems it would be in the best interest of the industry to produce units that don't waste water. I have seen the Unit offered by Kent" Deion 200R"- does not waste water and resins that can be regenertaed, perfect right? Well I have found nothing at Kent's resources about info such as GPD or anything else for that matter. Any experience with this unit or others would be appreciated. I hope we can wake up and do a little more to make this hobby less wasteful and less destructive than it already is. Thanks

[aquaman67]

I'd write to kent with your questions. I use a kent RO/DI and have asked several questions and have always gotten a quick response.

And there is a quick fix for you. Just plumb the waste line back into the feed line...

[frog_toad_99]

thanks for the advice, but if I plumb it back to the feed the unit would not work properly.

[discocarp]

Without RO you are going to BURN through DI. That's how I started out reefing. I'm not sure the environmental impact of the manufacturing of the recharge chemicals and transportation is any better than RO, not to mention dumping them down the sink. I don't know enough about it to answer that but it sounds like an interesting question.

A lot of us who are concerned about RO waste are finding other uses for it. Mine does not go down the drain. I fill my jacuzzi with it. I water my plants with it. I wash my clothes with it. If you are creative you can probably save at least a large part of the waste water.

Peter

[frog_toad_99]

Thanks for the thought, but I've tried to find other uses. I simply use to much water in a week to store or use what I waste. Anyone else on the KENT DEION 200R? thanks

[Flanders]

Toilets, showers, dishwashers, swimming pools, someone mentioned a jacuzzi -- also evil? I stopped worrying as much about wasting water when I found out that a local paper recycling plant uses about 500 million gallons each day. And this is an environmentally friendly example of how much water industry uses. Maybe that's an irresponsible way to look at it, but that's just the way I feel.

[purplehaze]

Originally posted by Flanders
Maybe that's an irresponsible way to look at it, but that's just the way I feel.

you are right, that is an irresponsible way to look at it....:eek1:

[Flanders]

Is it really though? I mean, I'm not saying that we should all turn on our faucets all day and not try to conserve water, but should we start labeling things evil just because they use water? If something cleans water it will be either wasting or polluting in some way.

Just offering another perspective...

[purplehaze]

Originally posted by Flanders
I mean, I'm not saying that we should all turn on our faucets all day and not try to conserve water

Now you are right.....
We all should try to conserve water by any means...;)

[frog_toad_99]

I simply said EVIL to get more ppl to look at the thread and HOPEFULLY offer some responsible advice. Oh well, the attitudes toward water related issues and especially clean drinking water in this country are sad. More Americans should try visiting or simply researching other parts of the world where families drink contaminated water from ditches.(I won't even start on drinking water in the US, scary!) In coming years we will see wars fought over water and water rights, so I believe it does matter that for every gallon of water I produce I WASTE another 3, I hope we could all think about it a little more and let the industry know we want change. This is not a an attack on you Flanders, that's your opinion, just giving my opinion back. Any one else on KENT DEION 200R? Thanks

[discocarp]

I agree with you, its sad that so much is wasted. But my gut tells me the amount of environmental damage by running just DI over RODI is worse. I wish someone that knew more about it would speak up. That's why I try my hardest to find a use for every single drop of waste water. The only time I don't use it all is when its very rainy and the plants don't need any.

Peter

[Shoestring Reefer]

I have a DI unit. I't not kent, but it's rated at 10 gallons per hour, that's 240 gallons per day.

In my area, I can get 150 gallons per cartridge, at $16/cartridge. Where I used to live, it was about 75 gallons per cartridge.

[PRC]

I'd have to agree with discocarp on this one. My gut feel is that running just DI is going to have at least as much of an environmental impact if not more than RODI. It will depend alot on your source water. Unfortunately I think RO is probably the best technology available right now. If there were something significantly better I'd imagine that industries that produce a whole lot more RO water than we ever will would be using it to save money (wasted water). Even in places where water isn't ridiculously cheap RO is still the most common form of purification when extremely pure water is required.

[SeaStar]

What is the definition of "waste" here.

I mean our RO/Di units are not producing a waste product that is unuseable, being hauled to some landfill and left to contaminate the earth for a thousand years. I look at it more like a constintly recycling resource. I agree it takes energy and money to purify it again and the purifying process may have some enviormentally negative sides to it (I really don't know what's involved in the purifing process although I believe alot of natural methods are involved).

The discharge from a Ro unit or the daily flushes of a toilet eventually make it back to that same Ro unit or toilet. If I water my lawn what is not taken up by the greenery eventually evaporates back into the atmosphere and is recycled again, correct. Even that which is taken up by the greens is eventually released back.

As far as other parts of the world drinking contaminated water. I don't think that has anything to do with us "wasting water". They simply do not have the means to process enough water. Not an enviormental problem but an economical one. The problem could be geographical also. "What's that you say, you don't have enough water. WELL WHAT DO YOU EXPECT YOU LIVE IN A DESSERT YOU IDIOT!!

Now i'm not saying we shouldn't try and be as efficent as possible with our water use as to limit the burden on public facilities and such. But again this is more of a economic relief. We have the technology to process all the water we need. Do we want to pay for it is a different story.

[discocarp]

That's not entirely true. Many locales are exceeding what they can get from renewable water resources. That water has to come from somewhere. Here in florida its pumped out of the aquafers. Aquafer levels are low. These are recharged by rainwater, and there just doesn't seem to be enough to keep pace with our growth every year. Many areas (mine included) are facing water restrictions even in a rainy year.

In most communities, when water goes down the drain, it is then "reclaimed". This water is not usually used for drinking, but for irrigation, often commercial, as its difficult to distribute to many individual houses. This procedure is costly, but not as costly as our drinking water is valuable. Water rights are going to become an important issue (and contentious one) in the next 50 years.

IMO, it is critical that RO waste be used. Every possible drop should go into something that you'd be using water for anyway. It IS waste if it goes down the drain. Even if its reclaimed for irrigation later, its a waste of drinking water. We may be using it for laundry and plants, but if we weren't, we'd still be doing laundry and watering the plants, and it would be a waste. It is critical that we as a society don't waste this precious, precious resource. That doesn't mean we can't use water for our hobby, but its our responsibility to not just be dumping it down the drain.

Peter

[Vincerama2]

Check this out;

http://www.wetwebmedia.com/rofaq4.htm

Someone here bought the DEION 200R...to regenerate the resin, you have to use muriatic acid and lye. So you decide if the waste product of recharging the dionizer is worth it or not. Anyway, read this and related RO/DI stuff on this page!

As for RO waste. If you could plumb it to your toilet, that would be cool. Water plants with it. How about just DUMPING IT OUTSIDE? That way, the water is NOT then adding to the volume of water that needs to be treated if you dump it in your drain. Instead, it goes where nature will take care of it. Plus, it's CLEAN. What we are "wasting" is not the water, it's the processing energy used to purify that water before it got to your house. Water IS renewable, even if you drink it, it eventually returns to the earth...it's the energy used to take out "non-water" elements that is going to waste here. So...toss it our your window, then there is no more energy required to process it, and the clean water can return to nature via evaporation...or birds and bugs will drink it!!

(Incidentally, you can drink the "waste". If you are willing to drink tap water, then the "waste" water is STILL TAP WATER, instead, the tds will just be a BIT higher but it's still clean water. Your body doesn't care, you won't grow algae or cyano in your stomach!)

V

[Shoestring Reefer]

Originally posted by Vincerama2
So...toss it our your window, then there is no more energy required to process it, and the clean water can return to nature via evaporation...or birds and bugs will drink it!!
Well, you are correct, but that doesn't help when one of the concerns is excess depletion of available drinking water. The water evaporated from your driveway will be rained down in someone else's watershed, not returned to yours. Also, water that does make it to the water table may not end up in your local water supply.

If you're in a rural area with groundwells, low population density, and abundant drinking water (like the area I grew up in) then using 40 gallons of water to do a 10-gallon water change isn't a big deal. That's not the case for everyone.

[Shoestring Reefer]

Holy cow!

The only major difference between that and my $32 system is that the resins are single beds, and have maby twice the total amount of resin. Other than that, it's just packaging.

By the way, mixed DI resin beds can be seperated. This article describes it:
Di Resin Regeneration (http://www.netpets.com/fish/reference/srab/srab4c.html)

As far as regenerating them, you're just talking about acids and bases. I don't see any environmental problem there, just a matter of the hobbyist knowing his/her limits before trying something like that.

Ok, so maby I'll go into business selling DI systems. Mine will have a carbon filter, then seperate cati and ani, then a mixed bed (because mixed beds clean up the water better-seriously: I didn't think of it first (http://www.culliganchico.com/html/commerical/Deion_Commerical.htm)). If the mixed bed unit bought cost me $32, and Kent's unit costs $200, then the unit I'm gonna sell should cost about $1400.

[discocarp]

Shoestring hit the nail on the head. You have to realize that there's a difference between water and usable drinking water. The comment about the evaporation raining down in different watersheds is very important too. This is one reason why water rights will become a very important issue in the coming decades.

As for the environmental impact of recharging DI, I think this is a very important question. I wish I could answer it. Don't forget to consider the manufacturing costs of the materials used to recharge DI and the resulting pollutants, etc. This is something I'd like to look into in more depth. I wish I had the time right now to do some serious research.

I also wonder (just musing here) if a mixed approach might be effective. Lower your waste ratio, let the DI do more of the work, but not all of it. Then there's less waste water to use (maybe more fitting with your lifestyle letting you use all of it). But you'd also have to recharge the DI less often, although more often than a standard RODI setup.

I think, all things considered, electrical costs are probably the biggest environmental impact our tank have. I don't have any info to back this up, just a gut feeling. I know I feel guilty setting up an SPS reef with insane lighting. I'm still doing it, but I try to cut power consumption elsewhere. PC light bulbs through the house, I drive my truck less and we try to take the higher mileage civic around town most of the time (unless the truck bed is needed). I don't think I'm making up for it yet, but at least I'm thinking about it.. In my next house I think I'll try solatubes to at least supplement the lighting.

Peter

[GreshamH]

Here in the Bay Area, we're extremelly concerned about the ground water table. If they don't keep pumping water into it (we have a resevour just for it), we get salt water intrusion and the actual land mass starts to sink. A major portion of all the Bay Area's water is piped in from elsewhere, just like Los Angeles (all theirs is piped in!!).

A good alternative to RO/DI is the Kold Steril by Poly-Bio-Marine. Great unit, and it doesn't deplete the natural alkalinity of the water, nor does it drop the PH like RO. Check their site for more info at: http://www.poly-bio-marine.com/products.htm

[frog_toad_99]

Respectfully… Seastar, I must not have made my point very well, but I must say I think you made it for me. "I mean our RO/Di units are not producing a waste product that is unusable, being hauled to some landfill and left to contaminate the earth for a thousand years" that is my point exactly, they are making a waste product, that is a given, the orange tube doesn't lie. What I originally wanted to know was info on this unit from Kent the "DEION200" that has the same results, but without the waste line. If the technology is present then I really feel strongly that it should be the industry standard. Why not? We’ve spent $$$ on our present units. IMHO this issue should be bigger than monetary concerns anyway. But, about the money.....Ah money, it is the part of this hobby that baffles me the most. We complain so much about prices and yet spend so freely.(Wow! It almost sounds like the American consumer in general, doesn't it?) Please more feedback from anyone would be appreciated, a quick note- Lets' not start splitting hairs on the "waste" issue please. We can break it down forever, I know, I can here it now… the water for the tank is in itself a waste, the plastic that holds the brine is a waste, ect. …. and trust me I’m liberal as hell and I’d love to go there, but not this thread, thanks. I’m simply saying why waste if we can achieve the same results w/o. And Kent DEION 200, anyone have it? Thanks for everyone's input Good day

[SeaStar]

F-T99, sorry if I was steering your thread off course. I agree with you that no matter what the definition of "waste" we should make every effort not to.
I can't help you with the Kent unit, but I would love to hear some feedback also. I would ahve no problem swapping out my standard ro/di unit. Well... at least at the next membrane change anyway. You may get a better chance of feedback if you post in the "reef discussion" forum. If you get some responses please provide a link in this thread so we can view info also.

[discocarp]

I think you are just going to chow DI resin too fast without the RO. That kold steril unit looks fantastic, no waste line, 5000 gallons capacity. Is anyone using this for a tank? This may be a great solution, even if you just use it pre-DI.

I also think if you go the DI route, you should still prefilter with RO. Adjusting the waste to a value that leaves you with a manageable amount of waste (ie: easily usable by you) with a lower water quality, then running it through the DI could save a ton in resin without the unmanageable amounts of waste straight RO produces.

Peter

[seaham358]

I have both the ro/di and kold steril... I like them both but the no waste is a great feature.
I use the ro/di for my reef and kold for the fowlr. I have used the kold on my 55 for about 6 months with no bad algae or other issue. Will post more later............ Survivor is on..........:p

[Bax]

I am new to the hobby but IMO, the way we spend money on these tanks so what if we blow some extra RO & DI media. Right?
I put guages on my water in and water out. I put a ball vavle on my water out. I turn the water on with my discharge open wide. It is over four to one waste to treated water. I then throtle back the discharge until the presure drop is around 5 psi inlet to outlet. Yes I will have to replace my resin at about nine months. So what! I have spent close to $1,500 setting up my little 26 gallon tank.
Just my thoughts.

[reefcam]

Wanted to chime in as I used to be a previous user to Kold Sterile. Well since last weekend. After looking over the unit and thinking hard about the media and what makes it work, here is what I concluded and what I did to change over and how you can also build one.

Original Unit. It's basically a chemical filtration unit where the first stage is a sediment filter (not sure what micron, but probably close to what the Poly-bio filter pads are). The second stage is activated alumina (like Seachem or Kent Phosphate sponge - but not sure if they are exactly cured the same way), which will remove phosphate and silica. Granted this is an additional purchase. But I did buy it. Then the last stage being the carbon to remove all other impurities.

So last weekend I tested my silica in my water since I'm having a diatom outbreak and sure enough it was the same as my tap water. Which basically put, my activated alumina has depleted and I didn't check. But the problem with the unit was my TDS was always what the tap water was. And not to get into why or why not strip the minerals. I leave that to another thread.

So what I did was gutted out my Kold Sterile unit and build the filtration from scratch. Now it's a 4 stage unit and after this weekend, it will be a 5 stage unit to really give equivalent water as RO/DI.

My first stage is a 1 micron sediment filter to remove any sediment and filter the water. Second stage consists of Marineland Black Diamond Carbon (reason for this carbon is because a well known reefer has tested this carbon to not leach phosphate, even though many brands claim they don't. So stick with Marineland or ESV Carbon. :) ) third stage is activated alumina (had some extra) to strip out phosphate and silica, and last stage is DI Resin to clean out the rest.

Now my TDS comes back 0. Phosphate and silica is undetectable. IO Salt dissolves nicely, and tank parameter is back in check.

Oh for the canister, check you local store (like walmart) and buy some clean water canister and you should also get some clear filter cartridges so you can see the media. Connect the canister in a series and you have your filter system.

If you are a DIYer, you can build a system for half the cost. Now you may need to buy more, but the average cost will be less.

For the resin, I bought 1 ft3 for $150 (including shipping) and it should last me many many fillings. Don't know how much per cartridge, but will know after I finish the package.

Hope this helps. I'm not one for wasting water either. I have roughly 500g of water to manage.

The secret to this whole setup is the flow rate. Even though you can get a lot of water, you will want to keep your flow rate to 0.5 gpm to 2 gpm. Depending on your tap water quality. Test the water output with a TDS meter to determine how fast or slow to run your water.

Jim

[Shoestring Reefer]

reefcam-
I've found places to buy resin before, but where do you get activated alumina, and how much $?

[Shoestring Reefer]

One place where you can buy Activated Alumina (http://store.ecompressedair.com/detail.aspx?ID=5). Is this repackaged and sold as phosphate remover?

[reefcam]

Mike,

I searched google for activated alumina and got some vendors. But haven't contacted them yet. I'll do that today and let you know. If the price pre 1 ft3 is not that cheap, I may just stick with DI to remove the phosphate and alumina.

Jim

[reefcam]

50lb bag... wow that's cheap and a lot. Just think, this is probably the same stuff you pay $16 / quarter lb for Seachem.

Thanks for the link. I'm going to call them up.

[Shoestring Reefer]

I'm gonna start selling stuff at half-decent prices. Can we delete this thread?




Oh, wait, it's already hidded in the "Responsible Reefkeeping" forum. This place is so empty, Bin-Laden could hide in here.

[reefcam]

:) I was thinking about that. We can start a company with sales office on the East Coast and west coast.



Bin-Laden has a reeftank too??? :D :D

[PRC]

I think I remember Eric Borneman mentioning that some animals are sensitive to the material used in phosphate sponges, not sure if that would be an issue if it's not actually in the tank. Also, if the TDS of the output water was the same as the tap water, won't you still go through a lot of DI resin?

[Shoestring Reefer]

I think what he was saying was, when the filter was depleted the TDS of the output was the same as the tap water.

[JAL2]

Does anyone use a permeate pump? I live in So. Cal. and recently installed a RO/DI unit with a drinking water storage tank (to store RO product for drinking). I plumbed the waste line to the drain. Now, every time I fill a glass with water, I can hear the waste trickling down the drain - makes me feel guilty.

I saw an ad for a permeate pump in a Marine Depot catalog. It is supposed to decrease the amount of waste generated (or maybe needed to flush the RO membrane). The cost was about $100.

I just looked for it and found this link:
Permeate pump from Marine Depot (http://www.marinedepot.com/md_viewItem.asp?idproduct=YSP5571)

The link says that it reduces waste by 80%.

Anyone have any thoughts/experience with one of these?

Jeff

[Shoestring Reefer]

That link also said this:

Important Note: The permeate pump is only effective when used with a bladder storage tank. Use of permeate pump does not have any advantage when being used with tanks / sumps open to atmosphere.

[JAL2]

Yeah - I just saw that too. Tried to post that info and got a server error. Well, I guess it would at least help me with waste generated for my drinking water. Also, I know that some folks store DI product in their bladder tanks - not for drinking of course.

[reefcam]

PRC, I'll still be going through the DI fairly fast. And I'm no expert at this, but just taking stabs at it, but if anyone knows, please chime in. My thought was to put enough cheaper prefilter before my DI to reduce the amount of impurities.

I always have a big question and will do a search, but what is TDS measuring for? And please don't reply with Total Dissolve Solids. :) What are the elements of the dissolve solids (carbon, copper, what? ).

As far as the activated alumina leaching aluminum into the water, I'm hoping the DI unit will remove it. It is a concern when we use Phosphate spone in our system where water is flowing through it from and to our tanks. In my case, I'm using it in a filtration system, so I don't think it is leaching into my system. I don't have a aluminum test kit so I wouldn't know. But my corals are growing and roses are splitting, so guess I'm not too concern.

RO/DI units are great, but I'm just opposed to wasting many gallons of water to get 1 gallon. Even at 4:1 ratio (wasted:good), it equates up to 200g of wasted water a week for me. Which is roughly 10000g of water wasted due to evap. And lately I have been doing 30g water changes a day, due to reducing silica from my tanks. So in 1 week I would go through 750g (total water) to do a 150g water change. Yikes!!!!

[PRC]

Here's everything you ever wanted to know about TDS http://www.usbr.gov/pmts/water/media/pdfs/TDS.pdf . I'm not really sure if prefiltering (other than RO) will have much of an impact on DI resin life or not.
I cringe at the thought of all that RO waste water as well, though I do try to use mine to water plants at least. From an environmental perspective I'm not sure which is the better solution. The RO/DI method certainly wastes lots of water, that's for sure. I guess the question is (and I think it's already been brought up in this thread) is it actually worse to consume the additional RI resin and other media since it probably requires significant resources and generates significant waste to produce. RO filters, on the other hand, are able to process considerable amounts of water and may not be as resource intensive to produce. I really don't know the answer to this, but I'd be very interested if anyone out there does.

[saleencobra]

Jim I would like to try to build something like you did. All I have now is a kent bare bones ro unit. So I would be basically starting from scratch. Could you post in a little more detail on what you did or maybe a picture or two. Thanks
Mike

[reefcam]

PRC, I see what you are saying. I'm having the same debate with a friend on this as well. Guess we will find out after a years of usage. And figure out how many filters each changes and the cost of it. Unfortunately, the test will not be all that great, as my tap water quality is fairly good around here. Our TDS comes out about 20. This has been reduced from 57. But our silica level is above 3+ppm. The salifert kit turned blue immediately after the last stage. Our phosphate is very low as well.

[reefcam]

Hi Mike (Saleencobra),

On top of this page is a little info on what I did. I'm not sure how the Kent system is plumb up, but all canister filters are built similar. You may just need to reverse the flow through the canister.

First off, look inside the cap of your canister filter. You will notice a hole in the center and on on the cover (or edge). Typical sediment filter will have the water flow coming into the canister from the hole on the edge and water exits the canister through the hold in the center of the cap. Hope this helps. So keep this in mind.

Stage 1: As with any filter, your first stage should be to filter out any sediment from the water. You will want the water to flow from the outside of the filter and out through the center hole.

The following stages are up to the person, but this is how I did it and I'll explain why, but then it probably doesn't make a difference, and a chemist will explain this to me.

Stage 2: Carbon Filter. I purchased a clear refillable cartridge from Dr. Fosters and Smith (but cheaper at kfswater.com - but haven't ordered from them yet). I filled the cartridge with Marineland Black Diamond Carbon (doesn't leach phosphate).

Stage 3: Activated Alumina (been told not to use it) to remove silica and phosphate. Reason for not using is because it leaches Aluminum back into the water. Still debating on this stuff, may switch to DI Resin

Stage 4: DI Resin - it pretty much absorb any chemical. Add this to your refillable cartridge.

I stuck the DI Resin last mainly to reduce the amount of compounds it will need to strip from the water source. Not sure if this will reduce the number of times I have to change the cartridge.

I just purchased some bulk DI Resin (mixed bed) so I'll save some cost by packaging the filter cartridges myself. DI Resin can be recharge, and will also look into this. As with many resin media (activated alumina, DI resin), you can recharge them. Some requires the use of acid to do so and I would rather pay a little extra for new material. One little mistake in recharging and I can cost my entire system. Not worth it to me. Plus playing with muric acid is not something I feel comfortable.

Let me know if this helps. PM me if you like to know the source of bulk resin. I don't want to post commercial names here.

Jim

[option61c]

I'm not really sure if prefiltering (other than RO) will have much of an impact on DI resin life or not.


Before I bought a 100GPD RO/DI I was using TWP for my makeup water. Here in S. Florida (Coral Springs tap water) a TWP turns black after only 30 gallons!!! I put a $9 GE fridge filter in front of it and the output quadrupled. In the end it was still more expensive than the RO/DI unit

[reefcam]

Thought I give an update on my water filter adventure. So I started with the sediment, activated carbon, activated alumina, and DI resin and at first this configuration worked great. TDS = 0, Silicate = 0 ; well that's all I cared for. IO dissolved instantly in the tub. But this lasted all but 1.5 weeks. Then silicate was more than I can test 3ppm+ and TDS = tap water level about 70.

So I got some bulk resin and now I'm running a 1micron sediment filter, activated carbon, DI, DI. I'm going to run a test tomorrow to see where the TDS sits and silica. This will be 2 weeks since I change out the DI resin.

If my silicate and TDS is up again, I'm sorry folks, but I'll have to throw in the towel and get an RO/DI unit. I konw, I suck. But had to try. :)

Here is why I would decide to get one instead of replacing the DI resin every 2 weeks or so. Water, although is wasted down the drain, in some cities, the drain water is recycled for drinking water again. Not sure if DI resin is BIO degradable, but I don't want to find out 5 years down the road there's a resin issue at the dump group. :) Okay, maybe it will not be that drastic. But the cost to run a RO/DI will be cheaper than doing DI only.

I'll keep everyone updated.

Jim

[saleencobra]

Thanks for the update Jim, sorry to hear it didnt go so well. I have been so busy trying to get my setup going havent been able to to mess with my filter, but will soon need to adress filling the tanks up.

Mike

[reefcam]

If you need to fill and empty tank quick, then using a sediment, carbon and dual DI filter would be the quickest and give you pure water. But after that, IMO, RO/DI would be the cheapest in the long run. I'm trying to see if I can build one myself. It's not complicated, just getting the components.

I'll update this thread on what I go with.

Jim

[Shoestring Reefer]

Originally posted by reefcam
If you need to fill and empty tank quick, then using a sediment, carbon and dual DI filter would be the quickest and give you pure water. But after that, IMO, RO/DI would be the cheapest in the long run. :thumbsup: Yeah, 10 gph = 240 gpd = a fast system for cheap, but the lifespan is just too short.

[PRC]

I know this is probably a major over-simplification, but if you assume that a typical RO filter decreases the dissolved solids in water by a factor of ten. Say from a TDS of 50 down to 5 (I'm expecting my inline TDS meter to arrive any day now so I should be able to get some real numbers on this at least for my water and my RO setup). I realize this is highly dependent on both the quality of the incoming water and the RO setup, but a factor of ten seems reasonable (and it's easy to work with).
Now, my understanding of DI filtration (which is pretty minimal at best) is that the resin depletion would correlate roughly to the amount of dissolved solids that it absorbs? If this is true then wouldn't removing the RO filter from the setup increase my rate of resin depletion ten fold?
If my assumptions are correct then this would hardly be a "cheap" alternative. More to the original point of this thread, my gut feel is that it would have a significantly higher environmental impact. To be fair I would need to know more about the manufacture of DI resin and the chemicals used to recharge it, but it certainly seems that this would be worse than using the extra water that RO requires.

[Shoestring Reefer]

Originally posted by PRC
I If this is true then wouldn't removing the RO filter from the setup increase my rate of resin depletion ten fold? Assumptions aside, yes. That's why manufacturers put DI resin AFTER the RO.

Originally posted by PRC
If my assumptions are correct then this would hardly be a "cheap" alternative. I agree, which is what I ment by:Originally posted by Shoestring Reefer
but the lifespan is just too short.

Originally posted by PRC
To be fair I would need to know more about the manufacture of DI resin and the chemicals used to recharge it, but it certainly seems that this would be worse than using the extra water that RO requires. A good point, too. I'm sure that the impact of the extra water required is different in a rain forest than it is in California, for example. Resins are recharged with acids and bases, and I have no idea about the manufacture of resins. Basically, they are plastic beads with a coating. I'll do some research when I have a change (unless someone beats me to it.)

[PRC]

I accidentally did some testing on the capacity of my DI cartridge when using non-RO water and discovered that it starts putting contaminants back into the water (in a a big way - TDS 600+ ppm from 172 ppm TDS source water) after about 6 gallons of product water! How did I do this? Run the RO membrane flush for awhile and you'll find out. Don't ask me how, but that's all I did.

[Shoestring Reefer]

PRC,
You're saying that when you fed water with 172 ppm TDS into your DI, you got 600+ ppm of product water? Was it color-changing resin so you know it wasn't exausted? Even if it was, the resin near the center can become exausted before the resin near the outside. I use a spoon to scoop out the un-spent stuff at the outside, then flatten out the spent resin, then add the good resin back in.

Also, I'm confused about what flushing your membrane has to do with using DI without RO. Are you saying you back flushed your RO and then sent the crud that had collected on the membrane through the DI? Also, what RO/DI were you using?

[PRC]

Mike,
To be honest, I'm not really sure what happened. Here's what I did. I just received my dual TDS meter and two each DI, carbon and sediment filters. I put new DI, sediment and carbon filters on my RO/DI system. I installed the probes for the TDS meter with one on the DI output and one on the RO output. I measured 6 ppm on the RO output and 0 ppm on the DI output. I made about 25G of water, checked both outputs (RO and DI) several times and they remained relatively unchanged.
Several days later I decided to check the TDS readings at various points in the filter system. I removed the probe from the RO output and inserted it on the tap water in line to the sediment filter. Got a reading of 172 ppm on the raw tap water. Moved the probe to the RO bypass out line and got a reading of about 180 ppm on the RO bypass water. Turned on the membrane flush valve to see if it made any difference in the reading, no difference. Moved the probe to the output of the carbon filter and got a reading of 172 ppm. Then I put the probe back on the RO output and started to make some water. I checked the RO output, still about 6 ppm. Then I switched the meter over to the DI output and it was going crazy, switching between low (0-999 ppm) and high (0-9999 ppm) ranges and finally settling in around 600 ppm. All this time I hadn't really noticed the DI cartridge, but now I looked at it and noticed that a bit less than the top half of the resin had color changed (yellow in this case). I replaced the DI cartridge (after scratching my head and grumbling repeatedly...) and everything was back to normal, DI output 0 ppm.
After taking a second look last night I don't see how it would be physically possible for the membrane flush to put dirty water through the DI cartridge. Nor does it seem physically possible to have accidently plumbed the system so as to feed dirty water to the DI cartridge, the tubing just wouldn't reach. Even if it had, I don't see how it could have depleted half a DI cartridge in a few minutes. I spoke with Greg at Reefgeek and he was perplexed as well. Oh well, I figure I just won't mess with it anymore.