First time Drilling

[fulkerl]

Hi I"m about to drill my 75 glass tank. My plan is two 1.5" holes in the back center, about 4" down and 4" apart. My question is this safe enough or should I put them further apart. Thanks

 

[eww]

Will the holes be 4" from center to center or will there be 4" of glass between them?

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[fulkerl]

4" between them, from bulkhead edge to bulkhead edge there should be 4". so hole edge to edge will be a little more.

 

[eww]

I would think that should be plenty of space for strength. Just go slow and steady.

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[fulkerl]

Will do, Thanks

 

[mcoomer]

There was another person that just wrote an excellent review of the process he used to drill his tank. Dig around for a few minutes and I'm sure you'll find it. Good info in there.

Here it is... http://www.reeffrontiers.com/forums/f12/drilling-my-tank-what-i-learned-63665/

4" of glass will be plenty of separation. Center to center would have given 2.5" and even that would probably have been sufficient.

Mike

 

[fulkerl]

Thanks for the link Mike, I thought that 4" would be enough but I read somewere that the center of the tank is the weakest spot and that made sense to me. I guess I started to second guess things, you know, thoughts of a large crack raceing across the back of my new tank as I start my second hole.

 

[dnjan]

Drains or returns?
1-1/2" holes are pretty small for drain bulkheads.

 

[fulkerl]

Just checked and hole size is 1.75" for 1" bulkhead fittings and they are for the drains.

 

[dnjan]

1" is pretty small for drains.

 

[fulkerl]

My return pump is 600gph with about 5 fet of head, one 1" drain should handle the flow and with two there should be no prolblems at all. Does this sound right or did I miss something?

 

[dnjan]

I would trust two 1" drains at that flow, but not one. One is just too close to "on the edge".
Don't forget that over time your tubing/pipes will accumulate deposits on the insides and the flow will reduce.

But, in my opinion, what you are really missing is when you upgrade the return pump to something with a better rate. Then, you will be stuck with undersized overflows.

 

[rainydave]

The Glass-Holes 700gph overflow kit comes with an 1.5" bulkhead. So...you might be pushing it with the 1".

 

[fulkerl]

I've read that you want 3-5x display turnover an hour. so with a 75 gal. tank that would put the flow rate at 225gph to 375gph, that would put my pump on the high side. I see no need for a larger pump or is there something i am missing? Thanks for your replys I would hate to see the errors of my way after drilling.

 

[dnjan]

I guess it depends upon how much of your tank flow is coming from the return and how much is from closed loop/powerheads.

At the flow rate you are talking (assuming your return is the only flow), your tank will be fairly calm.

My son had closer to 700gph on a 20-gal tank (with a seaswirl), and it was far from a high-flow tank.

 

[fulkerl]

I have 2 600gph and 1 1200gph powerheads for tank flow. the overflow is just for the sump.

 

[dnjan]

OK. Flow sounds better.
But I would still go with larger overflows. One snail could significantly reduce the capacity of a 1" overflow line.

 

[totem420]

If you have problems with drain.flow you could always keep the 1" bulk head and bush up to 1 1/2". I have a single 1" overflow on my 16 g bf with about 650 gph at my 4 ft head. I am very happy with my flow.

 

[fulkerl]

I like the bush up to 1 1/2" idea. Another question is it better to use flex pvc or solid pvc from bulkhead to sump?

 

[dnjan]

Flex can reduce headloss from elbos.