why does my freshwater reserve smell like cat pee?

[mjr]

I put fresh ro/di in a 30 gallon brute and use it to fill my ato and mix new saltwater. It seems that if I leave it in the storage vessel for more than a day or two, it starts to develop a cat pee or ammonia smell. I am guessing the ammonia is building because of the stagnation, but I am wondering if others have the same problem. Is this a common problem?

 

[philosophile]

Well... first, maybe your cat peed in it? But seriously, its likely that its got a bad case of mildew. Mildew likes moist environments like reservoirs for ATOs, and after awhile, it'll build up. So the next time the reservoir is low, instead of immediately refilling it, maybe take it out and give it a vinegar rinse and flush it with some tap water, before you fill it up again with RO/DI.

 

[Randy Holmes-Farley Verified Community Expert]

I've never had the problem, except once when I let the DI deplete, releasing actual ammonia into the output water.

But I have read of this many times and I'm not sure what causes it. Maybe a trace of ammonia from the DI, or maybe something else from the can or the air gets into it. Maybe mildew as mentioned above.

If a cleaning doesn't help with later batches, then I might measure ammonia, but in the absence of detectable ammonia, I wouldn't worry about it. You can often smell chemicals at very low levels.

 

[JOKER]

Mine will do that if I don't clean it regularly. I started giving mine a vinegar wipe down between fillings and have no troubles now. I will say my salt mix will do this also if I let it sit for more than 3-4 days. Using reef crystals and I also get a brown residue, I clean the salt container every time I do a water change. I am also using brute as my storage.