Design question

What if I ran an overflow box with 2 1" outlets(CPR102) rated at 1200 GPH and used a Mag-Drive 18 as a retun pump for my 72G. Would that be too much or overkill?

 

Complete overkill. I have a 1262 that replaced my 9.5 on my 90g.

You can run other things off your return pump, but if all you are doing is running your sump and/or fuge, you do not need a lot of flow. Tank circulation and circulation through the sump are two different things. All you need going through your sump is enough to supply your skimmer. so depending on what you have that could be anywhere from 250-350 gph? A fuge at most is going to take 100 gph. Were talking 450 at most for the 72g. A Mag 7 will do that with head loss. Mag 9.5 and call it good. Mag 18 is huge and will add to o much unneeded heat to your 72g.

 

it's not overkill to try to have 1200 gph of flow in a 72 gal tank (it's less than 15x turnover) - but you probably don't want all of your flow going thru the sump. just taking water in & out of your tank quickly doesn't give you the chaotic/random large volume water movement that you're looking for in a reef tank. Seems to me you'd be better off with less flow thru the sump and then something to make up the rest of your gph in movement inside the tank (powerheads for example)

 

So, is the 2 outlet overflow box a good idea with the 9.5? I just thought it would be easier to plumb the fuge with the dual outlet...

 

dual outlet is nice for 1) redundancy - in case something clogs one outlet, and 2) for ease of plumbing in your case

 

and the overflow will only take as much water as the return can pump back into the tank right?

 

Ya. I don't use an overflow box so I can't say what would be the best setup for that. Most regular 90g come with a 1" bulkhead that will do 600 gph. At 4 feet of head, a 1262 or 9.5 will do that no problem. You can do the same, have a little extra.

What do you have in your sump a skimmer? Do you have a fuge or do you have a W/D?

 

yes, a skimmer will be there(super reef octo 1000).. 20L - skimmer on the right, fuge on the left... return in the middle.

 

if you haven't bought anything yet, i'd recommend considering getting an internal overflow, rather than the cpr hang-on overflow box.

i used a cpr overflow for 2 years on my 75, and had a few incidents where siphon was lost and the display tank flooded. the little nipple that you're supposed to hook up a tom's aqualifter to for maintaining siphon tends to get clogged with debris, and mine even started to grow coralline after awhile!

you can get kits for drilling your tank and installing an internal overflow, or just drill holes and make a homemade one. then your floor isn't at (as much) risk.

 

The bottom is tempered, so I can't drill that. I have an overflow(not CPR) on my 20L right now and it's completly covered in coraline..