Diatoms, Dinos, or what?

[jhatfield]

Need help to identify this stuff... I've had this brown algae on my sand ever since I started this tank over a year ago. I've gone back and fourth on whether it's diatoms, cyano or something else. The tank is not in direct sunlight but is in a fairly bright room that gets morning light and that's when this stuff shows up every morning.

I've gone through a couple chemiclean treatments with no effect whatsoever thinking that it may be cyano.

Water changes have little to no effect either. Once or twice it was even worse the day following a water change.

The only thing it responds to is lights out for a couple days. But it always seems to come back. Photo below is a couple hours after sunrise with lights off.

Nitrate: .25
Phos: 0 (Hanna Low Range)
Alk: 7.9
Cal: 415
Mg: 1410

 

[Hanfam1111]

Piggy Backing here. Identical issue.
8.2 dkh
1 ppm Nitrate
0 phos
440 Calcium
8.2 PH
Tank has been Fallow for 6 weeks
Looking toward to hearing some possible causes. I get occasional Cyno and a few drops of chemi and it’s gone in 1 day. Doesn’t touch this stuff. I also get ALOT of reflective light in the morning

 

[Littlemikey]

Looks like what I have and from my understanding of it disappears over night it’s diatoms. After the tank balances out again it will go away

 

[WV Reefer]

I would try lowering the “white” light and upping the flow.

 

[BigJim]

Have you tested your water for silicate? That is typically what drives diatoms. I have a lot of silicate in my local water supply and I have to use a Silica Buster DI cartridge. I had frequent diatom issues before using that cartridge. The Salifert silicate test kit never shows any silicate in my water but an ICP test confirmed it. Silicate does not show up on TDS meters, so I had no idea I had an issue before that.

 

[Pntbll687]

I have the same in my tank for almost 2 years. It comes and goes. I've tried more flow, less flow, black out, no whites.

It comes and goes. Doesn't bother me anymore. I think I might add a couple two spot gobies, or some diamond gobies to try and turn the sand over constantly. This way it doesn't have a chance to grow.

 

[jhatfield]

Have you tested your water for silicate? That is typically what drives diatoms. I have a lot of silicate in my local water supply and I have to use a Silica Buster DI cartridge. I had frequent diatom issues before using that cartridge. The Salifert silicate test kit never shows any silicate in my water but an ICP test confirmed it. Silicate does not show up on TDS meters, so I had no idea I had an issue before that.

My latest triton test from March didn't show excessive Silicate... pretty much in the green.