Algae ID On Sandbed Only

Nick30G · Monday at 4:34 PM

Hi all, need help IDing an algae I have had for about 1 year now that refuses to go away; it only grows on the sandbed in a orange/brown color. Some parts of it grow in slimy mats with no bubbles in it but most of it is the dusty type. It blows away very easily. I take a turkey baster to blow it off the sandbed and it goes away for several hours only to return. Tank has been setup for 8 years. Im heavily leaning towards its Dinos and not cyano, im guessing large cell Amphidinium since its only on the sandbed. I could dose silicates, currently been dosing microbacter 7 with no results. Nitrates: 5-10 ppm, phosphates 0.117 ppm, no other algae in the tank. Its covers about half my sandbed in random patches, not really a problem just annoying to look at.

John Bolden · Monday at 4:38 PM

I had the same issue skimmer gho and light feeding and it always grew back after I sucked it out with a water change. I dosed silicates like you said and the stuff I dosed had a notice about coral which worried me but I dosed it and the algea completly went away! Every once in a while it came back then I added another dose and it would immediatly go away.

Nick30G · Tuesday at 9:09 PM

Starting dosing silicates yesterday, guess I will see how it goes.

John Bolden · Tuesday at 9:14 PM

Nick30G said:
Starting dosing silicates yesterday, guess I will see how it goes.

Great let me know your experience!

Nick30G · 2026-09-12T18:48:43-0400

Been dosing silicates for about a week now (Sodium Silicate 40%) 0.5ml for 1ppm per dose; was initially dosing 1x a week but have just decided to dose it daily because I have not seen any changes really; algae is still the brown type only growing on the sand bend; it grows in really thin and short slime mats/strings as shown in the photos. I wonder if I should get a microscope too to see if I can find out for sure what it is.