Bright green algae

[jandb]

Hello. Can anyone give me any advice in getting rid of this algae? It’s only on the acrylic, bright green and very hard. I good quality magnetic scrubber won’t remove it. The tank is established and has 2 Fluval Aquaskies on for ~7 hours a day less than full power. The worst side is a few feet from a west facing window. It’s been up and running for 15 years now without this much of an issue.

 

[HUKIT]

Green spot algae is often caused by imbalances in phosphate and/or CO2 levels, and excessive lighting. I’d start with checking your phosphate level.

 

[jjohnwm]

More plants might help by outcompeting the algae for nutrients. I think the single biggest difference might be seen if you divide the lighting period into two sessions, separated by a period with no illumination for at least a couple or a few hours around mid-day. Plants do well with this schedule; algae do not.

 

[danotaylor]

Beautiful group of geo's!
I get this type of algae in my tropheus tank when I slack off on water changes, and don't clean the inside front glass with a soft scrub scouring pad. One can assume if the nitrates are consistently >40 that the phosphates are also high contributing to the growth. It appears from the pics that the algae spots stop about half way along from the window, making natural light a factor in the problem. Do you need to leave the blinds open?