some advise needed

[seanb1]

i guess this question goes to people who have drilled their tanks.

tell me why i should drill my tank, and get rid of hang on the back overflows.

i just drilled a couple 29 gal tanks that i had laying around to use as a sump and a backup sump in case my pump quit, it was easy as heck.
im pretty confident i could drill out my 125 and am thinking of getting rid of the overflows.

just tell me why i should get rid of them please.

oh and a link to a thread here about where to position drains and returns would help alot since search option doesnt work most of the time.
size of bulkheads and pipe would be helpful also.

my tanks bottom cannot be drilled so everything hasta go in the back.

its a allglass 125, 72x18x22or 23 cant remember.

hope im not asking too much.
thanks.

[WaterKeeper]

Hi Sean (or Denise) ;)

The advantage of drilled overflows over hang-on's is that you don't need a siphon tube. It doesn't take much to break the siphon and cause a tank overflow.

I, myself, feel safer with the top drilled overflow you envision. A bottom drilled tank will empty in short order if a weir breaks. With top drilling it only lets as much water out as the overflow height. I like the top drilled even if it is a bit more obvious and the rockwork can be used to hide it.

I like two overflow, as if one gets an errant snail caught in it, the other can handle the flow. Usually a 1½ inch hole will handle even high flow tanks

[ILoveReefer]

my 90g has 2 1 1/2 overflows as you described. my tank is high flow with extra drainage in case if snail ir something gets stuck in one. Less chance of a flood. My holes are drilled in center of the back 6" center to center apart. 8" center of hole to top of tank. Allows enough room for durso modified standpipe. Miracles Under Glass recommended this to me when odering the tank. Miracles also drilled it.

[Playa-1]

By drilling the tank it allows you to gravity feed the drain pipe as opposed to syponing the drain. Gravity feeding is more reliable and less likely to cause flooding.

[korndogg091]

i have to agree with whats already been said. i used to have the hang on back and if the power goes out and the syphon stops, once the power comes back on you flood. a drilled tank is almost a must.

[tarax]

I have to counter that I use LiveReef HOB overflows and haven't had a problem with them when the power goes out.. They automatically start back up without a problem and have never had a flood after a power outage. I live semi-rural in that I am not on a city water supply and power outages happen quite frequently. My tank and overflow have always restarted without a problem.

I do agree however that a drilled tank vs an HOB overflow with syphon is a better way to go...