ro/di question

[cdh9400t]

would a 7 stage ro/di system with uv be good for a reef, or is that over kill.

[AZDesertRat]

The number is stages is irrelevant. Some vendors use it as a sales gimmick, like more stages is better. Thats bull.
You need 4 stages and thats it.
1. Prefilter- usually something in the 1 micron or less range is best to extend the life of the membrane and carbon block
2. Carbon Block- One is all you need if it is something like a 0.5 micron Matrix Chlorine Guzzler, even if you have chloramines.
3. RO membrane- a 75 GPD Dow Filmtec is the standard of the industry.
4. DI filter- A standard sized 10" vertical canister with a 20 oz refillable cartridge is best.

Thats all you should ever need unless you have something particularly unusual or bad in your water.

Don't fall for the e-bay hype about 125 GPD output, no manufacturer makes a 125 GPD membrane. Don't buy a 100 GPD either especially if it is a Dow membrane since the 100 is not a reverse osmosis membrane but is a nano filter which is much less efficient. Do buy a unit with a small horizontal DI tube which is right next to worthless.

Do get a handheld TDS meter, inline pressure gauge, RO bypass valve, Autoshutoff valve if you plan to automate things and standard sized filters not small throwaways.

[Jaycake]

Hi all, New member here, looking at an RO filter for the house and fish and was wondering if the RO filters at the home centers was a good fit.?

Thanks

[AZDesertRat]

No.
Most hardware or department store varieties are OK for drinking water but are marginal at best for reef quality water. Usually they have low production membranes in the 15-25 GPD range, coarse prefilters, granular activated carbon intended for taste and odors in drinking water and no deionizing filter.
You will find yourself spending more money to upgrade it that what you would have spent on a reef quality system with an added drinking water kit to begin with.
Make sure you get the reef quality system with the added drinking kit rather than the other way around or you will end up giving up important features you wil really want and need.
Some home center units even use proprietary replacements and will end up costing way more. Sears and Lowes/Whirlpool are one example, they use a non standard RO membrane so a standard Dow Filmtec 1812 series will not fit in their housings. Watts premier and others make some that require different sized prefilters and carbons and are harder to find and more expensive.

[2thdeekay]

<a href=showthread.php?s=&postid=11350449#post11350449 target=_blank>Originally posted</a> by AZDesertRat
Do buy a unit with a small horizontal DI tube which is right next to worthless. [/B]

I agree the small horizontal (10 inch) DI cannister filters are next to useless. However, if you have more than one and mount them inline, vertically, instead of horizontally, they work very efficiently.

http://filterdirect.com/catalog/product_info.php?products_id=85

I like the clear refillable models, as when filled with color changing DI media, you can visually monitor them, and refill them yourself with bulk media when needed. They are inexpensive to buy and inexpensive to use. You can add them to any RO filter. ;)

[AZDesertRat]

They work better than a single horizontal one but are still not as efficient as a true vertical canister/cartridge arrangement. The flow pattern in the true filter is much better and they still hold more resin than 2 of most the others inline or otherwise.

[2thdeekay]

May I humbly ask how are the larger cannister DI units more efficient? Could you describe the flow pattern in the cannister DI units, as opposed to the smaller, clear & refillable 10" units?

I admit that when these 10"units are mounted horizontally, they are inefficient due to channeling, and performance sucks!

I have the larger DI cannister units for my own reef, which are not refillable with bulk DI media. I had 4 - 10" clear, refillable DI units laying around, and mounted them inline vertically on a friends RO system. I was impressed with their performance. To me they seem to be just as efficient, but cheaper to use/refill than the larger cannister unit that I have. It's a nice feature that the 10" cartridges can be rotated to increase efficiency. Considering they are only $15 each, & lower cost of use with bulk DI media, they are probably worth keeping, IMHO.

[AZDesertRat]

Better contact or residence time and a dispersed flow pattern.

Refillable DI cartridges are only like $4 at some of the sponsors and can be used forever. Packed properly, which means fill the cartridge, tap it on the counter or tabletop, fill again, tap again etc until you cannot fit any more resin in, they will hold 20 oz of resin.