Im not sure how heavily planted your tank is, but I use Aquarium Products, Plant Tabs. They work well for me. I dont have many live plants in my tank...maybe 10 or 11. But they work really well. They are tablets that you just drop in the tank. Doesnt bother the fish at all. You use 1 tablet for every 5 gallons every 10 days. I usually just do it once a month, and my plants are very healthy. Sometimes it clouds the water a little bit...but it is usually gone the next day.