Is this good or bad algae?

[pinocchio]

I recently got a Second clean up crew of snails/crabs/hermits and a few days later I have this brown algae? Showing up on the sand bed. It showed up pretty much over night. Ammonia/Nitrite/nitrate are all fine. Tank has been established for months. I recently did a water change as well. Is this fine? Should I s

Image isn’t great but you can see how the brown stuff is starting to show up.

 

[pinocchio]

Meant to write “should I syphon sand bed or leave it”

 

[blecki]

Those are just diatoms. They normally show up on new sand a few months after the cycle and as long as your parameters keep in check they are self-regulating. They will continue to spread until they have depleted the available silicates in the tank and then they will die off and reach equilibrium.

 

[pinocchio]

Those are just diatoms. They normally show up on new sand a few months after the cycle and as long as your parameters keep in check they are self-regulating. They will continue to spread until they have depleted the available silicates in the tank and then they will die off and reach equilibrium.

Ok, so I should just continue regular water change schedule and let them be? Will increasing water changes help expedite?

 

[blecki]

No. Water changes are counter-productive. They feed on silicates, and should quickly deplete the water if there's no source. If you used reef rock and argonite sand, there really isn't a source for silicates except your new water. You've probably got a little in your water even post RODI (It can get through old/cheaper RO membranes and doesn't show up with a conduction based TDS meter at typical RODI water PH) AND there's probably a little bit of it in your salt mix...

Seriously just wait them out. When the silicates hit zero they will die.