Plumbing...suggestions? Added a drawing...

[Myka]

I'm good at putting it together, but my plumbing ideas usually suck!!!

I'm going to use this style of external overflow:


I have a 3/4" return, running a pump that will deliver about 700 gph. According to a plumbing calculator the minimum overflow should be 1.09". So I think I'm really pushing it to just use a single 1" overflow. So, should I put two 1" or a single 1 1/2"? I don't want anything in the middle of the back of the tank up high (esthetics), but I'm considering putting my return in the middle of the back down low say 3" off the bottom, then have two 1" overflows in each of the upper back corners. If I use two 1" overflows (which I'm leaning towards), should I use a single external overflow for the two across the whole back of the tank, or should each bulkhead have it's own external overflow?

Good idea? Bad? I dunno...? Suggestions?

I don't see many people with check valves on their returns, but I think I will. Is there any reason not to?

Also, can you guys post some pics of how you've incorporated a waterchange valve or some such into your plumbing?