Hello all...again. Thanks for all of your help with choosing the lights in my tank. The combination of actinics and metal halides look beautiful. I'll be posting pictures soon.\n\nNow, regarding my sump, I have a 30 gal aquarium that I am using for my sump below my 110 gal display. I am installing baffles/bubble trap with a spot for a fuge in the future and a protein skimmer. I have a custom siphon style overflow that came with the tank. (I like the CPR design better and am eventually planning an upgrade.) The setup also came with a external pump rated for 820 gph. My questions are these:\n\n1 - Can I run PVC from 1" above the bottom of the sump up over the top of the sump wall, over the wall using a 90 degree bend, down the outside of the tank using another 90, and into my external pump with another 90? Is that too many corners restricting flow?\n\n2 - If I do this, what diameter pipe should I use?\n\n3 - I have read a few horror stories about using a ball valve to restrict flow on the return to the display. Any experience with this? The alternative given was changing the diameter of the return pipe. Is there a formula to use in calculating this or is it trial and error. It all seems a little goofy to me.\n\nAny thoughts are appreciated. Thanks again to all for previous and future ideas.