I use dechlorinator for chlorine and chloramines when adding topoff water. I also have plants, the best solution to water quality problems. Use a combination of surface plants (water lilies and/or water lotus) and oxygenating plants. I also use water canna, purple pickerel weed, sagittaria, Japanese iris, parrot feather. Never had a problem since adding plants 5 years ago except for predators and fish that occasionally jump out due to overambitious sexual escapades in spring. I also add Mosquito Dunks just in case. Good luck.