Originally Posted by elimmel

your setup (if light kept at 18W) is meant for a low maintanance tank with no co2.

your rotala and Lilaeopsis brasiliensis would prefer more light and co2.
with low lights and no co2, they are not going to do very well... maybe even beginning to stunt.

coupled with your fert dosing and no water changes, the slow growing plants and possible stunted plants are not able to take it up fast enough.
with 10 hrs of light and abundant ferts, any ammonia produced by bioload or rotting plants will trigger algae and keep it going.

manually remove as much BBA as you can. do a large water change and stop dosing ferts. replace the 2 plants with ferns, crypts and low light plants. you might want to replace the lotus too.
feed fishes daily to provide the ferts. lower lights to 8hrs for a start and slowly increase back to 10hrs if needed. as usual no water changes, just top up.