It's like a powder type brown algie. Okay thanks. I'll have to check my levels on the N and P. I know I need to add more snails. I've only got about 12 in there and the ppl at fish store recommended I have about 75 snails.
LFS are selling large CUC because it sounds like it makes sense.
You get more results on all nuisance algae by keeping N and P in the low ranges
Snails are great for "œhelping" keep things clean, various kinds do various things, but they cannot rid the tank of algae, and they don't do much if anything for silicates.
When you put in a mass of snails, they will start to die off quickly as food diminishes, their death adds back nutrients to the water and thus the problem starts all over again, sometimes worse.
In your sizes tank I would add
10 Nars for sand cleaning
20 Ninja Astrea for the green algae
5 Mexican turbos for the brown alage
Sponges stop diatoms as sponges consume silicates to build their structures, so diatoms have nothing to feed on.
They will pass anyways on their own