Rust on Sand?

I'm not sure what is on my sand but it looks like rust. I've seen cyano and it doesn't look like that, I'm not 100% sure what diatoms look like but after doing multiple water changes over the past 2 months and even leaving the lights off for two days this stuff comes right back. I use the AquaC EV-120 protein skimmer and that stopped working for about a week and that's when this stuff started to take over the sand bed. I also have not noticed new coralline algae growth in awhile but the corals are still growing fast! Does anyone know what it might be?





Here is another picture with the flash on.

 

You sir have diatoms! I have them too and they are ugly

 

Ceriths and Nerites eat diatoms. I have about 30 Nerites, ranging from small to large, in my 55G. Haven't seen diatoms since I added them.

I have a lot of Ceriths too, but the Nerites really knocked them out.



Dwarf Planaxis will eat them under the sand bed. Nerites don't burrow.

 

diatoms that is what I think.

 

Diatoms get my vote.

 

I check out adding a new clean up crew since most of my snails are gone.

 

I have at least 32 times turnover with my water flow and I tried Chemi-Clean almost a month ago and this didn't solve the problem.

 

Aim for 42 - 50x turnover.

http://www.reefcleaners.org for some Nerites.

 

Do you have a fuge and macros?

 

Try Reefcleaners.org. They have a custom clean up crew section and will fix you up fast. Stay away from the Chemi-Clean until you have exhausted other resources. A good cleanup crew will do the same thing in a much more natural fashion.