Do you age your salt water for at least 24 hrs before use?
I would not add any buffer or trace elements. They are not need and will cause problem if the level get too high.
Your anemone is doing poorly because of poor water quality. There is problem with your water test. Ammonia is toxic and should be 0. Hardy fish can tolerate .25 ppm (part per million) but not anemone. You don't give units to your measurement so I cannot tell how much ammonia you have. It seem that your tank is poorly equip to handle anemone. I would just try to remove the anemone to a better tank, more mature and better run tank. Your clown will be just fine without the anemone. If you don't, it likely will died in your tank.
If you try to keep than anemone, I would do 50% water change every other day for a week. Mix and age the water for at least 24 hrs prior to use and don't add any additional buffer or trace elements. Make sure you top-off your tank daily at least. Make your you have a good heater that keep the tank temp stable at about 80 degree.
Clean water condition, temp and salinity stability is what you need to get your anemone better. Your additive is likely not a minor part of the problem.