Not really an emergency but...

Robb1414 · Sep 17, 2019

My tank has been up and running since December. Always had a pretty clean tank. This am I saw this. What is it and what do I do? It is only contained to one side of the tank (at this point). This is a FISH only tank. All water parameters are perfect. YIKES!

Tuan’s Reef · Sep 17, 2019

Seems pretty normal to me . Do you siphon your sand bed during a water change? How’s your flow? What size tank and what pumps do you have in there now?

Also a sand shifting goby or other critters that do that will help.

Softhammer · Sep 17, 2019

Yep, extremely normal. Will improve with age.

Jay Tosi · Sep 17, 2019

it could be a type of cyano or diatom it should not harm anything so you're good

Billdogg · Sep 17, 2019

from the brownish color I'll guess diatoms. Perfectly normal. At least in all of my systems over the years, they will come and go throughout the year, especially spring and fall when the ambient light (the sun) changes position in the sky.