I know it's not unheard of when tanks are only a few months old to have an algae bloom. I've been trying to get even a little control of it but to no avail.
Background: It started after I added some osmocote root tabs deep under the sand substrate. I pushed the tabs all the way to the bottom with tweezers so I don't know why it's getting into the water column, unless one of the capsules broke near the surface of the sand as I was pushing it down.
Tried so far: 3-day blackout treatment immediately followed by a tank flush - 90% water change. It looked pretty good after this, then went right back to green. I added sponges to the intakes of both filters, and polyfil floss inside my HOB filter. Still green.
Lighting: two 6500k T8 LED bulbs in a converted fluorescent fixture (33Gal/125L) = 22.4 Watts/Litre
Special Concern: I have live plants and don't want to harm them, and most algae treatments that I'm aware of are pretty harsh on plants. I also have snails and shrimp that I don't want to harm with chemicals.
Thanks, it apparently is arriving today! The Excel, lowered lighting and willow branches have improved the cloudiness, but it's kind-of reached a plateau so can't wait to put this filter in as soon as it arrives!