I'm not sure if you were able to straighten your problem out. Did you add the SLO that seems to be the thing to do from the jump and is very efficient. I would do one more thing that would benefit your fish and plants and also keep the fish poo stirred more and that would be trying to get more water movement in my fish tank. Your water will be stirred up more which will also give your fish more current which they will benefit from and also possibly add more oxygen to everything bc of the extra water movement on top of the water.