How do you test RO?

[newkidfish]

I have just tested our RO from the LFS using two different freshwater nitrate kits, the readings were V high, so I rang LFS to establish if they regularly test the water and when they change the filters. They said that the test kits give false readings on RO and that they have special particle tests done to ensure their RO is of good quality. Can anyone comment on this, can we use our ordinary test kets to get results that can give us an indication to quality?

[Macca]

You test RO water with a TDS meter. It should be as near 0 as possible. I have never tried testing nitrates as I did not think it was necessary.

James

[liquidlogic]

yes. you do by using a TDS meter. i recently purchased. a 6stage 75 gpd. with top of range inline tds meter :D. (sry). setting it up soo. it shud always be on 0 but if i rises u know its not producing 100% quality water. so its a sign that ur filters / membrain needs changing. tbh purchasing an ro is a great buy. i got an amazing bargin on mine. great buy .

andy

[newkidfish]

what make unit did u get and where from?

[flying Jock]

Hi

As said a TDS meter will let you know what your ro unit is taking out and how much is going in through your main supplies.

It is always worth testing phosphates or nitrates once every few months to make sure all is in check.

I have also heard about false readings via nitrates but i would ask your LFS for a reason as to why he said it does.

Cheers

FJ

[Paul P.]

I tested my home produced RO water a while ago, just out of curiosity really as my TDS reading was 0, nitrates, nitrites, ammonia and phosphate were all 0, so that leads me to believe if your RO has a 0 TDS reading then there is no dissolved solids in it (as it should be)

might be worth testing a sample of your LFS`s water for a TDS reading(you can buy a good quality pen type TDS meter for about £15) i`d be very surprised if it had a 0 TDS if you are getting high nitrate readings, and don`t let them fob you off with " your containers aren`t clean that`s why you are getting a reading" get them to put some in a small container that you know is food safe and sterile or get them to put some in one of the (hopefully clean) bags they put fish and then test the TDS, a penny gets you a pound that you get a TDS reading above 0 !

this is one of my pet gripes and unfortunately it is becoming very common that some LFS`s sell people supposedly pure RO water only for people to find out later that they have been pouring crap into their tanks and having to pay the LFS for it !

[subz88]

I've read that some (not all) saltwater nitrate test kits aren't suitable for testing freshwater, but the information you've been given regarding your high nitrate readings doesn't sound right to me. If you have some deionised water or deioinising resin you can run a simple test to see if the kits you have give false readings.

I run an inline TDS meter, and check my RO water with a nitrate test kit every couple of months.

[newkidfish]

I think for all the money I give the fish shop each week for RO (£6 a week) it would be worth my while getting my own RO unit and TDS metre. But this will have to wait a bit as just investing in a new deltec skimmer