diatoms
If your using regular drinking water for your water change then that's your problem. That is usually loaded with nitrates and phosphates and other elements. If your water changes are small buy distilled water and bring the water up to the correct properties such as ph. They also sell a filter that produces water similar to ro it's inexpensive. The name escapes me right now. Again if your tank is small u must do weekly water changes or at least biweekly with correct water
If your using regular drinking water for your water change then that's your problem. That is usually loaded with nitrates and phosphates and other elements. If your water changes are small buy distilled water and bring the water up to the correct properties such as ph. They also sell a filter that produces water similar to ro it's inexpensive. The name escapes me right now. Again if your tank is small u must do weekly water changes or at least biweekly with correct water