return pump/overflow question

[mikeandjenn99]

I am getting ready to start the transition to a sump, and I have a question about flow. I have an overflow (HOB) that is rated to 600gph. The pump I am planning to use will be around 300gph at 4ft hh. Will I lose siphon if the overflow is rated higher than the pump, or will it only siphon out at the same rate the return pump is pushing water back in?
Thanks!

[luke33]

You are correct, you'll be fine. You only run into a prob if your return is more than your overflow. Or something rediculous like 100gph on a 600gph rated overflow. But that would still work, it would just be noisy in my opinion.

[mikeandjenn99]

can I reduce the pipe diameter to slow the flow rate from the overflow? Would that help with noise at all?

[Steverino]

Hopefully your overflow has the ability to stop and start without losing siphon, with the use of a chamber that the U-tbbe sits in, or else the bulkhead that carries the water out of the HOB has a stand-pipe type of tube that always keeps a couple of inches of water in the HOB chamber.

Look at this link, go down to figure 7 to see what I mean about always having water in your HOB so that the siphon does not break, using a stand-pipe in it and keeping a couple inches of water in it.

http://www.reefkeeping.com/issues/2003-01/gt/index.php

[Heyguy74]

I use a durso standpipe to reduce the noise. Check out the DIY section. Scroll down to overflow and click on the Durso link. Its really cheap and easy. I would suggest that you put a ball valve between the overflow and sump. This way you can service the sump without losing the siphon. I also suggest one on the return line as well.
Another thing is either put a check valve on the return or drill a small hole near the water line of the pipe (inside the tank) to make sure you lose the siphon if the power goes out.

[luke33]

Mike, what overflow are you working with? Also, set it up and see how noisy its going to be before you go out and buy something you may not need.

[mikeandjenn99]

I'm not sure who the mfg is, since I got this as a swap for some frags. It has an area for the u-tube to sit in some water, so it won't run dry. Here's a picture of what it looks like now -

http://www.reefers.org/album/images/3583_334699.JPG

[Steverino]

As for not losing the siphon, you are in good shape. But the white pipe inside the HOB looks a little high. You could/should do the durso style for noise reduction.

[mikeandjenn99]

Unfortunately, I am pretty much stuck with that pipe. Whoever made the overflow, glued that pipe in, as well as the attaching pipe on the outside. I'm not sure how I'd get it apart without breaking the bottom.

[mikeandjenn99]

ok...disregard that. The inner pipe was just really stuck. I rapped on it with a small hammer from the bottom, and it popped out. So I can put a durso style pipe in there now :)

[luke33]

Mike, that one looks good...you may pick up a new utube, that one's pretty nasty. Something to think about. Its a 600gph overflow by the look, doesn't matter who manufactured it, there all similar. U-tube's in my opinion are the most reliable. One suggestion, if you want to quiet it and slow down the flow, add a sponge around the syphon where the water drains through the bulkhead. That will slow it down a bit and maybe quiet it down. I don't think it will be that loud anyhow. Give it a try like it is at first, and then go from there if its unbearable.

[mikeandjenn99]

Thanks Luke. Btw- I have a sponge that fits around the inner pipe, so that part is all good to go