zozo
Member
So the main tank will always have the same water level as long as the pump is running but any evaporation will lower the last compartment ten fold ?
That is fine if you are home every day to check it otherwise you will need an auto top up?
Yup that's the case with any sump. Autofill would be nice but since it needs mechanical stuff then an overflow in the sump is required as a fail-safe. Similar to the overflow in the toilet cistern prevents flooding if the valve fails to shut.
As said in this case it could easily be prevented with drilling a little hole under the pump outlet. That will equal the water level with the aquarium. A 1mm hole will already be enough for that.
If you don't then this will be your evaporation reservior. Marked in blue. What's that 1 litre? Refill every day.