RoDi water

[Gooners]

I had a major issue last week with nitrate levels in my display tank. I test the water I was adding to the tank for nitrate, this showed as 0ppm. I did a 50% water change and in a few hours the levels had risen again. I did tds test this was showing as 6, still confused I tested the water direct from the Ro unit, again no nitrates but I took a further step back and did an ammonia test. This showed high levels of ammonia at 2ppm.
This thread is to advise people to check their water for more than tds and change your filters more often.

 

[KorD]

I have seen this before, but it delt with stuff leaching from the storage container it was being kept in.
you never know how a container was treated or made until you can check it out at home

 

[Gooners]

KorD
I might agree with the leaching but I've been using the container for 18 months for only Rodi water. Also since changing the filters no more ammonia detected.
Also the last test that showed ammonia was direct from the ro unit not the barrel.

 

[lavoisier]

I would always try to keep TDS at 0.

 

[Randy Holmes-Farley Verified Community Expert]

While RO/DI water can certainly have ammonia (usually from chloramine), and can actually have much more ammonia than the incoming water as the DI depletes and releases a lot of stored ammonia, I do not think it likely that 0 ppm TDS water can have 2 ppm ammonia. I think 2 ppm ammonium in water will read close to 2 ppm TDS.

One or the other measurement is potentially in error.

The ammonia also is not the source of the nitrate rapidly rising toward 60 ppm following a 50% water change.