Tetra® WaterClarifier clears cloudy aquarium water caused by overfeeding, gravel dust and other minute suspended particles. This phosphate-free liquid solution is safe to use in all freshwater aquariums. This effective formula works by causing small, suspended particles to quickly clump together. These larger particles are then removed during normal power filter operation. This formula is based on clarifiers used to treat drinking water. It’s safe to use with fish and plants and will not affect water pH levels in your aquarium.Unlike many clarification products on the market, Tetra WaterClarifier is safe for fish even in very soft water (low KH) conditions. However, in extremely low KH conditions, below 1KH, half dosage is recommended. If in doubt about your water’s hardness, perform a 20% water change before treatment. Be sure to use Tetra AquaSafe® water conditioner for each partial water change and Tetra EasyStrips™ Test Strips to measure your water’s hardness.