arkmann;2021194; said:I think its just normal evaporation. I have a 100 gallon and a 30 gallon wet/dry. The 100 is covered while the sump is not. I lose about 1" of water from the main tank in 5 days, just in time for my 5-day water change.
In a 5 day period that sounds reasonable. My water level decreases in a 24 hour period. It's a 100 gallon tank. So imagine a 100 gallon filled up to about 80% then 24 hrs later it's down to less than 10-20%