Help me identify. Diatom??

[Dyln]

Hi All - I have a pair of clownfish in a 105l tank. It is almost 4 months old now.

Salinity - 1.025 [H2Ocean classic formula salt + RODI water]
pH - 8
Ammonia - 0ppm (Salifert test kit) + Seachem ammonia alert
Nitrite - 0ppm (Salifert test kit)
Nitrate - 7.5ppm (Salifert test kit)

I do 10 to 20% water changes depending on nitrate levels. Recently, I started vacuuming a quarter of my sand bed when I do water changes to control nitrates (I had slightly higher nitrates a couple of weeks ago). I dose Seachem stability every time I vacuum. Ammonia and nitrites remain at 0 ppm. I take that as I am not hurting my bio filter. However, I will go back to vacuuming a small portion in two weeks time.

I am feeding pellets/flakes (started flakes 3 days ago) two twice a day. I stop feeding them as soon as they stop eating. Now they eat anything that drops to the bottom as well.

Could you please help me identify what this is? Is it diatom? Any advice to tackle this would be much appreciated.

 

[Stephen8169301]

I can’t say for sure but with the age of your tank your more then likely hitting the ugly phase now have you tried blowing it off with a turkey baster?

 

[Dyln]

I can’t say for sure but with the age of your tank your more then likely hitting the ugly phase now have you tried blowing it off with a turkey baster?

Thank you for the response. I don't have a turkey baster (at least a clean one to stick in my tank). But I tried aiming my smaller wavemaker at the patches, and it doesn't seem to want to leave the rock.