overflow box positioning?

[arcab4]

thought i might as well start a new thread. be easy for people to search thro the archives later....

for my tank, should i place the builtin overflow box in the corner or in the middle? ???

and is there a specific type/size of built-in overflow box for different flowrates? or is it one flowrate? my return pump is returning 570 gph. and the overflow rate should be higher than that right?

[dattack]

You can put your overflow box at one corner and return probably in the other side of the tank in order to have a nice flow.  Your overflow box should be rated higher than your pump.  Usually the flow rate of the overflow box depends on the size of the hole and U tube.  I think a 1 inch U tube and 1 inch bulkhead flows at ?600 gph?  I am not sure.  
But if the flow from the pump is to strong, you can make a T again with the return so it returns some water back to the sump.  You can use a ball valve to do that.  But I think 1 overflow box might match your pump given that the head pressure from the pump will decrease its return anyways.

There are overflow boxes with 3/4 inch which is slower and some where there is 2 holes which allow for about 600x2=1200 gph.  You would then need two 1 inch U tubes.  You can block one hole if you want a slower flow.

[arcab4]

so i would have an overflow in the left corner and a powerhead in the right corner?

i have an extra powerhead..where to put that one?

is there any benefits in having it in the corner compared to having it in the middle?

so tell me if this is right. in the box, there's a hole for water to go into the sump. and then there is another hole for water to return to the tank. i think i'll go do some more research on it.

thanks,

[dattack]

I am not sure I am following you but do you have a built in overflow or are you going to buy a HOB overflow?  Or did the tank you just buy have a hole drilled in the back glass for bulkheads?
That info will tell you what you need to do. ;D

[arcab4]

it's a builtin overflow. i got rid of that cpr hangon overflow. so i'm going to have it drilled on the bottom (thus i have to drill my stand) and then drill another hole on top (opposite side of the box) to snake in my powerheads. how's that?

[dattack]

Hey so your tank is not drilled yet?  

[arcab4]

nope. actually i can specify on how it's going to be drilled since it has to be ordered. customized! any suggestions.

[dattack]

Ah ok.  So your can put your overflow in the middle if you wish but usually I see it in the corner.
You will probably need a hole to fit a one inch bulkhead.  That would probably give a flow of ~800gph.  Sometimes people who wants even higher flow might have two holes drilled next to each other for two bulkheads.  They will have the other one plugged if not in use and the other one could be 3/4".  It depends on you of course.
For the water return from the sump, you can have it flow back in like a canister filter outlet or if you want it tidy, you can have additional holes drilled on the back glass for return.  You just need a bulkhead fitting again and attach the hose from the pump sump to bring water back to the tank.  The hole return drilled would probably be 3/4 inches.
Remember that bulkheads require holes that are drilled larger than their "size description".  For example, I bought a bulkhead that requires a 1 3/4inch hole for it to fit right.  You have to measure the bulkhead you are going to buy.

[arcab4]

is 800gph too much since my return pump is only 570gph?

so if i have a 1inch bulkhead, my hole should be about 1 3/4inches?

now the return..i think my lfs mentioned that it would come out of the same box. is that possible or do i need to drill another hole (originally i had it planned that the returnwater would go thro one of the corner holes (top of tank).

so there is no advantages to having a corner or middle box right?

thanks..i'm just full of questions today.

[dattack]

It could return from the same hole overflow but you got to make sure you are not cycling the same water.  Everything should work well if the hole tank gets circulation somehow or another.
800 sounds good to me.  You always want your overflow to be faster than your return so there's no problem with that. Just make sure once again that every corner of the tank gets water flow otherwise it could be a problem area or dead spot where algae and such will grow.
Your LFS should show you one of their display tanks on how the plumbing works at least.  Go to any good fish store and there is always a reefsetup that will give you some ideas.