Ok, first off do not just start a siphon into a tank below, no matter the water will overflow the sump eventually, you can not adjust a siphon to the changing volume of water that is returned to the aquarium. You need to have an overflow box inside your tank, that is where the siphon will be from. The return from sump to tank if any is where you put a restrictor valve or bypass, do not ever limit the intake side of pump, will burn it up. Once sn overflow box is set up, there are many ways to do this, look up online, or I can elaborate later.
Make sure your return has a siphon break hole in it as well. I made a mistake once and forgot to put one in my return, mine drained my entire 125g tank because I set up an under
gravel return system. I am just warning that a siphon directly into a tank will overflow your sump, sounds like I did it well by accident. I pit my siphon from my box into the tank not the overflow by mistake and the pump did not keep up with siphon for very long and I had a shower in my basement for 1st floor with about 20 gallon of water.
Make sure your return has a siphon break hole in it as well. I made a mistake once and forgot to put one in my return, mine drained my entire 125g tank because I set up an under
gravel return system. I am just warning that a siphon directly into a tank will overflow your sump, sounds like I did it well by accident. I pit my siphon from my box into the tank not the overflow by mistake and the pump did not keep up with siphon for very long and I had a shower in my basement for 1st floor with about 20 gallon of water.
