Steo the great
Aquarium Advice Freak
I top up with ro water once a week and its usually aout 25 litres in one go. And I have a 600 litre aquarium should i top up more regularity or is this ok
Basically turn off your return pump. Then fill your sump as much as you can without overflowing(allow some gap). Then turn on your return. When the water level in the sump stops dropping mark your sump. This is your absolute max fill line while the return is running.
Check everyday and fill to that line.