RO Water @ my local Supermarket...now what

[Avonlea,PA]

My local supermarket has one of those cool RO water dispensing machines. I filled up a 5 gal. bucket the other day for $1.25.

2 questions:

1) I have a TDS meter on the way. What should the reading be?

2) I was thinking of taking a sample to a water testing lab to get a good test done (I don't have personal test kits yet, because I'm not ready to fill my tank). What should I ask them to look for, besides chlorine and copper?

:fish2:

[DgenR8]

Testing by a lab, I think would be pretty costly. You could probably set up an RO/DI of your own for about what that would cost.
Use your TDS meter, reading should be close to zero, definitely less than 5.

[tiggerk27]

I would take a sample of the water to my LFS to test it if you don't have the kits. I was using RODI water from my local supermarket and it turned out they very infrequently did maintenance on the machine. In the end my tap water was better quality.

Kim

[Avonlea,PA]

Originally posted by DgenR8
Testing by a lab, I think would be pretty costly. You could probably set up an RO/DI of your own for about what that would cost.

I was thinking along the lines of culligan for testing. I have to try to weigh the options in my case. I live in an apartment, and can't hook up a permanent RO unit, so everytime I wanted to use it, I'd have the hassle of setting it up and then having to monitor it. Plus I'd have the obvious filter and resin costs. And lastly, I have to pay for my water, and I'd hate to be paying for all that waste water. It just seems more logical to get it at the supermarket if it turns out to be good water.

Use your TDS meter, reading should be close to zero, definitely less than 5.

Thanks

[LX302]

If your looking to keep cost down and no permanent installation you can use the RO unit by Aquarium Phar. available at Thatpetplace for $26.05. You just need to purchase a cartridge every 100 gallons or so for $15.25.
Better than the stuff from the supermarket and like others said with quality issues.

"Tap Water Filter (Aq. Pharm.)
This highly efficient highly affordable water purification system is perfect for your fresh and salt water aquariums. Removes dissolved minerals. Heavy metal, algae promoting nutrients, chloramine, and organic pollutants. Includes ph adjuster, electro right, faucet adapter, and 8 feet of kink free tubing. Only one cartridge operation and maintenance easy. Filters 10 gallon of water per hour with NO waste water. Comes fully assembled"

[tang_man_montreal]

Has anyone used that above mentioned water filter?

Any issues with Chlorine/Chloramine?

I can't install a permanent solution where I live, so this product might be the key for me to stopping trips to the supermarket! :)

[WaterKeeper]

Bard of Avon;)

To answer your original question---- the resistivity varies dependant on the total dissolved solids (TDS) of an RO units feed water. A good RO unit removes about 95% of the TDS. If you start out with a water that only has a TDS of 100 you will have almost 10 times purer water than if the feed water has a TDS of 1000.

To get ultrapure water you need to add DI. This can produce a water which is close to theoretically pure which has a resistivity of 18.3 million ohms (0.055 microsiemens).

The need for such purity is really not needed for tank make-up water. RO water with a resistivity of between 50,000 and 500,000 ohms should do nicely. That corresponds to a TDS of between 14 and 1.4 mg/l.

It is probably correct that testing for everything would be cost prohibitive. If you did I would add TDS, ammonia, nitrate, phosphate and silica to your list.

I don't know about the product from Aquarium Pharm. but you should be able to get a lot more water from an RO unit than 100 gals. If you use a particulate prefilter and carbon block to remove chlorine the membrane should last at least a year or two.

Hope this helps.

[tang_man_montreal]

I've looked around...

The aquarium pharm. unit is listed as a DI unit, and not an RO unit...

Everyone raves about RO and RO/DI water.. but what about DI water?

[DgenR8]

Running DI alone, with no prefilters, will exhaust the resin very quickly.
That's why the TWP (Tap Water Purifier) is only good for something ridiculous like 100 gals.

[tang_man_montreal]

Thanks for the clarification on that... :)

[WaterKeeper]

I agree with Larry. You get roughly 20 times the life of DI canisters that have an RO unit preceeding them.

As I said above there is no denying that the best possible water is derived using DI. The question is do you need that purity? I have one tank that gets only lab grade RO/DI that is at least 17.8 megaohms and another that just gets only RO treated water at an average of 123,000 ohms. Both tanks are doing well.

I do weekly 10% water changes which, IMO, are part of the reason for a sucessful tank. If you skimp on water changes you may wish to consider the added purity that a RO/DI unit provides. The 5% or so of impurities that a RO unit misses will build up over time if you are prone to infrequent water changes.

By the way, that 17 meg water drops to a lowly 450,000-900,000 ohm after it is aerated and stored for 24 hours. That is mainly due to dissolved gasses entering the water during aeration.

[Avonlea,PA]

Originally posted by Avonlea,PA
My local supermarket has one of those cool RO water dispensing machines. I filled up a 5 gal. bucket the other day for $1.25.

2 questions:

1) I have a TDS meter on the way. What should the reading be?

:fish2:

Ok. I got my Hanna TDS meter today, and I checked my supermarket water. The reading was 001. My tap water was 225. Is it safe to assume that the supemarket water is good to go, as long as I can confirm there is no copper or chlorine in it?

I also realize that if I go this route, I will need to test the water each time I get a fill up.

any comments?

BTW, I've used the Tap Water Purifier, and it's just a complete pain in the arse to use, and it's not really that cheap.

[Avonlea,PA]

I forgot to mention that the Tap Water Purifier water had a reading of 071.

Just got another bucket, from a different location (same chain) and it has a reading of 002.