How to fight Gravity

[bellaroxio]

1) Per advices from you expert, I am adding a reservoir tank and will be using the JBJ ATO. Due to space limitation, the reservoir will be 3 feet higher than the sump which means the pump in the reservoir tank will be higher than the sump. When the water level in the sump is good and the pump is turned off by the ATO, how do I break the siphon pressure so that the water won't freely go to the sump through the pump due to gravity?
2) Which is better, protein skimmer on the refugium side or on the return side TO the tank?
Thanks for your expertise.

 

[yannifish]

I'd put an airline tubing check valve on the top of the tube, this will allow air into the tube but will not allow water out. Others may have a better way, but thats what I have on my return pipe, and it works just fine.
Whenever possible you want separate water flow to the skimmer and the fuge, because if the water flows through the fuge then the skimmer, or vise versa, some of the benefits of the fuge are cancelled out, because either the nutrients or the conepods will be skimmed out. Its better to split your overflow so that some water goes to the fuge, and some to the skimmer, and then to the return pump from both.