Could be mad Java Fern not liking the too bright light.
Algae.
Possibly diatoms, are you fish-in or fishless cycling?
You could try Purigen to take up/ bind some of the free floating particles of silicates.
What kind of substrate is it?
Are you feeding fish or seeding flake food for ammonia? Maybe if you need to feed fish use a pelleted food.
Phos-Guard if maybe too much Phosphate.
And if you need to seed to create ammonia get some pure ammonia from the dollar store, ace hardware or other source. Pure no additives for cleaning.
Increase water flow. A small powerhead should help too. You might try lowering the water a little to get more splash if it is a hob filter. Or increase flow if it is adjustable.
A Mystery snail might be able to help clean if it is safe for a snail at some point.
At what stage are you in you cycle?
Reduce lighting time. Try a split photo period leaving the light off for 1-3 hours in the middle of the day, in case there is algae in there too.
Java Fern doesn't care for really bright light. Possibly lower the Java Fern or raise the light???
What size is the tank and what kind of light? What is the K rating on it?
