Your Stem Plants
Review the growing requirements of the plants that aren't doing well. I don't believe Cabomba will do well floated. It may need to be planted as the others may too.
There are stems that grow well floated like Anacharis, Pennywort, Water sprite and Water wisteria. Some of the other stems may need to be planted.
Check the lighting requirements too. Your single bulb may not be enough for the plants that aren't doing well.
Floating particles can be removed by using polyfiber in the filters. The dense medium is designed to attract and hold floaters in the water. Keeping the tank topped off is the proper way to maintain it.
Plants prefer acidic water (lower pH). Your water is hard, so it has a higher pH. But, that's not really important. The plants will adapt.
Research the above. You may need to make some small changes.
"Fear not my child, just change the tank water."