Questions about building overflows and drilling a tank?

[SuperFudge]

Hello,

Seastar is drillable on all panes.

If durso is 1.5" and feedline is 1" and you leave a decent space between holes for flanges and the walls of the overflow for flange space you need about 8" minimum inside overflow dimensions.

Keep in mind Sea star puts cleats on inside seams of alot of their tanks, also euro bracing.... these also influence sizes of overflows.

There is no more danger of flooding with internal vs external overflows, nor does the gallonage have to be decreased,likley it is just the opposite...instead of taking inside of tank space,youve actually added more. but yes, it will have to be placed further from the wall to accomadate them.

The best overflow possible is also the longest possible length of "spill over" with that in mind external can be done full length without taking any space at all from your reef.

Marc.

[Richy44]

likley it is just the opposite...instead of taking inside of tank space,youve actually added more. but yes, it will have to be placed further from the wall to accomadate them.

My thoughts too, and I do not have to worry about space behind as it is a built in wall tank..

Rich.....

[Palster]

Originally Posted by Fudge

If durso is 1.5" and feedline is 1" and you leave a decent space between holes for flanges and the walls of the overflow for flange space you need about 8" minimum inside overflow dimensions.

Thanks everyone for your input. So when you say you need a minimum of 8" inside overflow dimensions is that total spill over length or do you mean the overflow has to be 8" by 8". Also are you saying that one overflow of this size would be able to handle the flow for this tank. I was thinking of using eggcrate at the top of the overflow (this is how it is done on my 90gal).

It looks as though there are a fair number of people running external overflows. It certainly would be easier than having to drill the tank. Aside from having to move the tank further from the wall I can see some advantages. I did read an article on one website where the author was claiming that when the power goes out and comes back on if the siphon for the external overflow fails to start back up when the return pump comes back on then you can have a flood.

Glenn

[Richy44]

Outside overflow. Have a glass Co. notch the tank 2" and build your overflow boxes on the outside. You can go with the lifereef overflow boxes too but, I was talking about building your overlow boxes on the outside not inside your display. You can either notch the tank or drill holes near the top of the tank to feed the overflow boxes.

Rich.........

[Palster]

That explains the confusion. I was thinking of the of the siphon style overflow boxes. Those are the ones that I believe can cause flooding for the reason I had mentioned in my last post. I had never considered notching the glass and building the overflow on the outside.

Glenn

[Richy44]

[SuperFudge]

Hello,

The total length would be your length of the overflow x1 and your depth x2.

so an 8x5 oveflow would be 18" of actual surface skimming.

But i couldnt say it would be 5" in depth because i was unsure of bracing (cleats and or euro) in your tank...the 8" is a minimum width to fit a 2 1/2" hole(1.5"bulkhead) and a 1 3/4" hole(1" bulkhead) aswell as the street 1.5" 90 that you will use on your durso, aswell as typical flange size.

You/glass company must notch the top, rather than drill holes here, holes will not work.

Marc.

[Palster]

Thanks Marc for all of the information. According to Reef Central's Drain Size Calculator an 18 inch overflow will handle up to 1200 gph which should be enough flow if I decide to make the tank a reef tank later on.