Brown build up on stones

[Tacoeater]

I get this brown build up on my cichlid stones after a week of my last pwc. It blooms on the 5-6 day, right before the next pwc is due. It scrubs off really easy with a brush, should I leave it on there, will it eventually turn into green algae? I noticed my Mbunas try to pick at it right when it blooms. It looks like what use to get on my glass, but almost completely gone now that I do bigger water changes once a week and started using Purigen.

 

[MMantelli]

It looks like diatoms. How long had your tank been set up and what are your normal test results. There common in new tanks and usually go away unless you consistantly have high nitrates or a lot of silica I belive in your water. Best bet is to reasearch diatoms in freshwater aquariums. I had an issue with them for the longest time untill I got so sick of them I transfered my mbunas filter and some decorations to a Rubbermaid tote for a day and totally cleaned the entire tank all the decorations and even rinsed the substrate out. Been doing 2 med pwc's a week and haven't seen them since. And my lights on like 10+ hrs a day. Sounds like there going away though just keep your nitrates as low as you can and they will slowly dissapear.