phosphate in my Ro/Di water

[acer]

I have an Aqua safe system that turns out great water regarding TDS= less than 5 , but I tested it today for phosphates and results were not zero. Is this possible?? advice please..

[Mike O'Brien]

you might want to add a DI unit. Still compared to the ammount of phosphate added in a single feeding it's likley trivial.

[flyboydave]

I have an Aqua safe system that turns out great water regarding TDS= less than 5 , but I tested it today for phosphates and results were not zero. Is this possible?? advice please..

5ppm? Are those old cartridges? A mixture of dissolved solids with a TDS of 5ppm isn't bad, but I wouldn't want 5 ppm of phosphates going into the tank.

When my cartridges are new, TDS < .67 ppm. I change them when they get to 2 or 3 ppm. Not that 5ppm is bad at all, but since I have an auto-topoff system, when it first starts up that 5 ppm water will be about 20ppm for a minute or so.

I guess I need to get a pass-to-drain kit.

[AquaFX]

Membranes do an excellent job at phosphate removal.

Either the membrane has been compromised, due to age, scale, chlorine or something else; or the test kit is off.

The last thing is DI, the DI will remove the rest of anything the membrane can not remove. If you have a salt water tank, you want DI quality water.

How high was your phosphate reading? And how old is your membrane?

Let me know, I do anything I can to help!

Marianne
www.aquafx.net

[acer]

I think the DI is spent or the test kit is old and inaccurate. The RO/DI is only one year old and only makes about 10-15 gallons a week, a few times has made a 50 gallons week= water change in the 90 gallon reef I have. I will by new test kit tomarrow- or bring a sample of my RO/DI water to LFS to do a phosphate test. If it does not agree with my current kit I will buy a new one. If it does then I will try new DI resin. THe phosphate measured between 0.0 and 0.5 ppm , not 5 ppm. According to another "expert" this is a high amount of phosphate in a reef system and I should do water changes. BUT, if I put water in that already has 0.5 phosphate reading - how is that going to LOWER the phosphate at all???

[Mike O'Brien]

If you have inorganic phosphate in you're tank water, then it's a problem. If not then the small ammount of phosphate you're adding isn't really a problem. Not that you shouldn't try to get it lower. Phosphate is in great demand in a reef tank and is utilized really fast. Most of us are adding it on a continual basis to the tank and still can't get a reading of inorganic phosphate.