Is there such thing?

[barchtruong]

My tank's been running over 2 mons now.
The cycling part was done long time ago.
Now, Why my tank starts having brown Diatoms again?
I Changed water weekly at 10%.
Changed on Sat. and the brown stuff showed up yesterday, Sunday.
Brown stuff showed up after I removed 4 biowheels fro the 2 filters on Sat.
Phosphate is 0.
no Trate, Amo. Trite,
1.026 SG,
76F at night, 78F when lights are on.
8.2 PH
Corals are very healthy.
Skimmer was broke for over aweek.
New better skimmer just hooked up for 2days.
I don't know how brown stuff comes back?
Anythought SWfans?
Thanks

 

[geridoc]

What kind of water do you use for topoff?

 

[barchtruong]

I've been using DI all the way through whether topoff or water change.
The only time I used tap water was the very initial filling up time.

 

[keyah1]

What size tank do you have?