matching gph between overflow box and magdrive

We just got 2 Magdrive pumps, 600gph. They're great. Just one problem though, and that's the whole conceptual jumble of overflow box ideas. I like the acrylic ones, can someone explain to me HOW exactly to build one so that when the power goes out it does not fail? I understand it's not about particular dimensions as much as relative dimensions, such as the water level in the outside compartment being lower than the aquarium water level and all that.

The refugium I built (pictures up when the system is complete) and the protein skimmer I built (ditto) are both going to be using these 2 pumps, but obviously with the refugium I want the pump to regulate the rate of water flow. It's said that a good overflow box/weir will only siphon as much water out of the tank as the pump puts back in. So my question is, how do I know if a particular overflow box design can handle up to 600gph?

Thanks guys

 

If you are buying the overflow box, they usually have a GPH in the description. Are you going to use both pumps?

Use a gate valve on the return pump to find the sweet spot. Gate valves are more accurate and easier to dial in than ball valves. I have a ball valve on one of my tank's sump pump and it's annoying. Occassionally I have to adjust it and it's not easy to move at first so when I loosen it I always go too far and have to readjust it a few times.

 

Crap. I just saw what forum this is in. Duh. Ok you are going to make it... let me see what I can find.

 

Ok. I need to get back to work (damn day job), but I think you might find some answers here:

http://ozreef.org/index.php?searchword=overflow box&option=com_search&Itemid=27


One question is how wide is the drain pipe? This affects everything.

 

The only parts I have so far are the acrylic sheets, I haven't bought any spouts or nozzles. I'll look up the items you mentioned, thanks for the ideas. If you happen to get any more, I'll be glad to hear 'em!

 

http://ozreef.org/index.php?option=com_bookmarks&task=view&id=368

This seems to be a copy of that Melevsreef page. Do you guys think that this overflow box design would handle 500-700gph? I'm thinking 7" or 8" wide... I mean, I think that'd be enough to allow that much flowage but I'm not really an expert on this yet.

 

I found a overflow calculator:

Looks like you need to go big! Or have more than one...

ALTHOUGH - Keep in mind 'head loss' - how the flow slows down with more feet of pipe. For example:
MAG 7 - 700 GPH .....425 GPH@5'
MAG 5 - 600 GPH ......350(est. from looking at graph) GPH @5'

 

sweet! Thanks! I'll definitely use this info

 

Thats some good info I gess I wil need like a mag 9.5.