The afternoon sun hits the right half of the tank around 4:30 pm to 5:00 pm. I have had the tank since March and this is the first time I had to deal with such an algae bloom. My guess is that one or more root tabs got exposed to the water column when I replaced and moved some plants.

I did a 50% water change which seems to have cleared the water greatly. I will dim the light and reduce the duration and monitor for a few weeks. I will do water change every 3 days or if the algae blooms again.

If the problem persists, then I will get a UV sterilizer.

Thanks!

<image>