Do you have a heater in your tank? If it’s cold in a room and warm in the tank, the condensation will increase. Usually, just lowering the aquarium temperature few degrees will alleviate the issue. Another contributor to condensation may be the flow rate. For ideal performance and to reduce moisture build-up on the bottom of the tray, be sure that the water pump is set to its lowest setting or just slightly higher. This will reduce splashing from the main drain line, as well as water draining through the emergency overflow holes. Check also to make sure the drain fitting is completely clear.
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