I found some in the states...

Check Valves

Are these the ones you guys are farmiliar with?

The ones I'm thinking of are made by Wise, I believe. Those PVC ones look like they would freeze up in no time. Not sure if you've ever seen inside reef tank plumbing, but it's real ugly inside and lots of room for a swing valve to get stuck (Open)

Also, read this thread re: hammer effect of valves.

http://www.reefcentral.com/forums/sh...ht=check+valve

No, never had the pleasure :confused:

There must be some out there better then! Right? :exclaim:

Thanks for the link....Wouldn't want hammering...But I too was thinking of putting in a bypass. I guess all I would need is a ball valve on the tank side I could shut off for the check valve swap.

I think what I would do is come up over the back of the tank, down to the bottom and build a pvc manifold to discharge from the rock work. This gives you the effect you want and gives you the safety of a siphon break in the return. I just wouldn't be able to live with holes in the bottom of my tank that could allow for the tank to empty. And in my experience, when a check valve gets stuck, it will be when you're sleeping or not home. And it isn't IF, it's WHEN.

So far so good with my check valves. After three years of continuous use...no problems. Still have enough room in the sumps just in case, though.