ATS now developing yellow algae

[stevec]

Hi

I have been running a diy scrubber for about a year. It was slow to start off. I went through a blossom of GHA on the rock and sand bed, I suspect due to detritus built up in both. I had great growth of algae on the scrubber. After a couple of months now the GHA is disappearing rapidly and the algae on the scrubber is now along with some green algae growing thick yellow growths.

Screen is 25 sq" and 40watts LED.

Would it be right that there is no longer enough nutrient in the water to grow the algae as I have pulled it out of accumulated phosphate/nitrate in the tank? I was running the light 18hours a day and is now running at 8 a day.

Is this simply I need a more thougher clean of the screen?

Cheers
Steve

[SantaMonica]

It's probably just a lack of nutrients, like you said. One thing though... the original high growth was from a build up of nutrients (mostly phosphate), not detritus.

You can test this by over-feeding 3x as much each day for a week.