brown stuff in fresh water

[droidus]

I use a smart ato water system. I keep the lid on top of it. I noticed that there is some brown stuff that has developed inside of it, and was wondering what it is.

 

[DLHDesign]

To confirm; this is RO/DI water at 0TDS?
How quickly does it develop? How often do you clean out the bucket, in other words?
Is the lid on tight (and, if so, how are the cables passed through it)? Or does it just rest on the top, with the cables coming out between the lip of the bucket and the lid?

Where is the tank located in relation to the bucket, and where is the output line of the ATO? It's possible that when the ATO shuts off, it draws in a little bit of saltwater in a back-siphon. This could cause the RO/DI water to develop some debris.

 

[droidus]

Yes.
It took several weeks, and I never cleaned it out. The lid is on it loosely enough to let the cables in. The tank is located above the bucket.

 

[Chuk]

I would wager a guess that it’s algae.

 

[droidus]

I thought it was maybe some dirt & grime that built up over time.