Brown color in my sand bed

[arriel66]

Help!! Every time U turn on my MH and PC, some spot in my sand bed turn brown. If I don't have enough flow, then even when my lights are off, i should have some brown spot then. Will it be my lights or still the flow? Thanks in advance.

 

[1329eheim]

If you're getting brown growth in your sandbed, I'd say it's likely excess nutrients causing diatoms, cyano, and/or dino growth. All of these are photosynthetic, of course, and so respond to light, but to control them, I'd recommend you focus on reducing nitrates and particularly phosphates through the usual means: GFO, carbon dosing, growing and harvesting chaeto, reducing feedings, doing regular water changes, etc.

Good luck!