Originally Posted by bigrift
ok iv been fghting with this for a while now and its starting to agervate me. i have a 75g tank with a 20g sump. everyday i add water that evaporates and always the same amount and everyday my mt wants to overflow and i have to make adjustments to the sump to stop that from hapening. what im not understanding is why when i add water to the sump dose it pump more to my mt. the pump is 1000gph and my overflow is out of the back of the tank with 2 1 inch outlets. so yeah i dont get it why dose the amount of water in my sump make my pump put more water into my mt. iv been thinking of upgradeing to a 40g sump but im afraid ill have the same issues. any help would be apreciated.
take a pic of the overflow system. how much water are you adding to the sump? what kind of adjustments are you making to the sump? overflows are usually rated for 750 gals/hour so first off, i think your return pump is too big. if i were to guess you are topping off a decent height of water because there is less head pressure on the pump when you add water ( water has to travel less distance away from gravity to the mt) causing more water to enter the main tank (pump not fighting against gravity to send it to the tank thus pump sending more water), and seeing that you are already over the rated amount of the overflow your water level in the tank rises. so to fix this you
1. either have to put pressure on the return pump
2. use a smaller return pump
3. add more hose to the return plumbing
4. lower the amount of water in the sump
5. put the sump lower than it is now.