Nitrates from bacteria in mt RO storage tank

[Drauka99]

I have 2 - 55 gallon barrels for my mixing station, one is for mixed SW and the other is for RO/DI water. I noticed about a month and a half ago that the RO container had a thick coating of clear slime on anything I left in there (hose and pump for the transfer to the other barrel). Since then my nitrates in the display have increased by a good margin. TDS on the RO/DI measures = or less than 1ppm before DI and 0ppm after.

Could it be the bacteria in the RO container get killed in the SW environment and release nitrates?

Currently the barrels both sit with open tops but that is only until I get the last of the supplies to finish plumbing them together with an external pump. Then both will have their tops replaced and only removed when mixing

 

[Randy Holmes-Farley Verified Community Expert]

That seems unlikely to me, unless the RO/DI is not working. The nutrients (N, P, Fe, etc.) for anything growing in the RO water need to come from somewhere before they can be made into bacteria. Even if there was a small amount of N and P in the new salt water, it would almost certainly be a small amount relative to the large amount you add every day in foods.