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I'm doing it! (drilling my tank)


Dec 22, 2004
After another frustrating evening of trying to get my sump plumbing in order, I've decided that all of my problems are coming from the damned pool hose my siphon overflow uses, so this morning I crossed my rubicon. My overflow, drill bit and bulkheads will be here next week, and I'm draining the 75 over Thanksgiving.

I'm planning a single curved, full-height internal overflow from www.dursostandpipes.com. I plan on drilling for two 1" bulkheads in there for reliability. I'm only using one overflow instead of one at each end because I don't think I'll ever have enough flow to overpower a single box with two 1" side-drains. I'm also going to drill for the return so I can have a spray bar without having to go over-the-top. PVC return with only one 90 elbow!

Hi Dan,

I seem to recall reading that sometimes (usually? always?) the bottom glass is made of tempered glass and that makes drilling a tricky operation. Is that a concern for your tank? If so, what, if anything, do you do about it?

Brittally yours,

What to do is simple--don't drill the tempered panes :smile:

Most tanks with a tempered pane usually only have the bottom, although for a long time all 55 gallon (and I want to say 45) tanks were made all-tempered, before drilling became trendy.

I'm in the process of upgrading my 30 gallon clownfish tank to a 38 with the same footprint, which I'm going to drill this weekend. I emailed All Glass to ask about the tank before I even ordered it to make sure the side panes weren't tempered.

My 75 does have a tempered floor, but the sides are OK. Durso style-standpipes are candy-cane shaped and fit into a floor-mounted bulkhead. Since many of us can't drill the bottom, there is a popular modification of the Durso where the bulkhead is towards the top of the back pane and the "arch" of the candy-cane goes through it.

A lot of time today on Reef Central that I should have spent working :smile:

Hey man have you thought of drilling in the side? This is what I'm gonna do.


I have found a place that will drill with the tank still assembled.

You could still octo proof this fairly easily I'd say.
I'm probably going to drill towards the top, just because the glass is under less pressure there. As far as I understand the laws of physics, the water shouldn't care if the street elbow is coming in and down from the back wall instead of in and up and down from low in the side wall.

To be honest, I was expecting having a hard time octo-proofing the overflow box. There's nothing really on the back of the tank-wall to attach to. That's the real bonus of the PVC system in the RC thread I linked to. The downside of that setup is it looks like it has very low efficiency as a surface skimmer compared to an overflow box. That would be the only reason that I wouldn't build it that way. Perhaps one of the heavyweights could come in here and give me their opinion? :smile:


PS re: drilling. I ordered a new diamond-coated hole-saw off eBay for $10 with shipping. A glass shop that does it is probably going to use a similar bit, just with a drill press so the bit doesn't skate around and scratch the glass. I'm going to use a 2x4 with a guidehole in it to start the hole to avoid that problem. I also bought a big pile of 1" bulkheads off eBay for $3 a piece. LFS and pool shops seem to charge around $10.
Looking up at the eggcrate in my office, I don't think it would be much of an obstacle for an octopus. I posted the question we were discussing last night on RC, but as of yet I have no responses. You might want to go in there and give me a bump, its on my old thread in the DIY forum (probably on the second page, by now).

I've been doing thought experiments all morning. Right now I'm considering a glass overflow box similar to the one in your friend's picture; except it does not go all the way to the floor and is longer so it gets more surface water. It would have a glass shelf 3/4 ~ 1" wide along the top on two or three of the sides to provide a lip for clamping on some sort of octo-proofing material.

I'm still considering the in-tank PVC setup on the RC link above, with modifications. Imagine it with long wide holes cut in the bottom of the main PVC tube. Imagine that part wasn't glued in the T's so you could twist the big holes up to the top of it. Then some sort of non-moving cover on the bottom (like one size larger of PVC cut lengthwise into a trough and glued to the T's). Most of the time it would pull water in the small holes and be octo-proof. Every few days when I know I'm going to be in the same room for a few hours I can stick my hand in, rotate the big non-octo-proof holes up, and skim all the crap off the surface when I can make sure the octo isn't going in.

Yeah lots of people make the overflow box long for the extra surface skimming, I think many also have two dursos. In regards to octo proofing, have you thought of having overflow teeth/combs that go all the way to the roof of the tank? Would make it easier to build, and you wouldnt need any clamps or anything.
Now I'm thinking about doing something real similar to Detritus' setup, except using some green aquarium netting for the actual octo-proofing rather than the filter pad.

I'm still thinking about the internal PVC one. Probably just easier to go simple with it--grind the top of the long pipe right off for big linear overflow dimension, and the octo-proof it with said green netting and some cable ties.

I'm wondering whether green aquarium netting would last very long. What if you used fiberglass window screen? I had an old lobster tank with an overflow. I made a frame of pvc that fit into the overflow and then sewed windowscreen with nylon fishing line over the frame and then placed that on the overflow.
That's a good point. To be honest I hadn't given the material much thought other than I wanted something other than filter material prone to clog.

I discovered this last night:

The Hofer Gurgle Buster

The water inlet is between 1/8" and 1/4" of an inch thick. I think that would effectively be as difficult an obstacle for an oco to get through as screen or net. Right now I'm considering a glass overflow box without any octo-proofing material covering it. The octo could go in the box if he really wants to, but I'd have two Hofers so he could only ever block one of them at a time.

id be worried about my tank overflowing with that one cause water is a freak thing that likes to travel up and if that thing gets clogged or something your screwed
joefish84 said:
id be worried about my tank overflowing with that one cause water is a freak thing that likes to travel up and if that thing gets clogged or something your screwed

There are a few ways to combat this:

1) there would be two of them for redundancy, each able to handle the total flow on its own

2) my system as it is now cannot flood. My pump is on a shelf high up in the sump. If I were to have an overflow failure the pump would run dry and burn itself out before the display tank flooded. My landlord's floor is worth more than my pump.

After this project is done I'm going to wire the pump to a float switch so even in the event of a drain clog it shouldn't destroy the pump.

I think the HGB design is pretty robust. There are a couple ways its design mitigates these risks:

a) Despite being thin, the drain gap goes around in a decent sized circle so its a little less likely for one object to completely seal it off

b) In normal operation it works as a drain without siphon action. If flow is restricted and the water level rises, it will overtake the vent tube in the top. Once that happens and water fills the chamber BOOM a real powerful siphon action (with above average head due to the flood) is going to increase the capacity and probably suck the clog straight through.

With my new tank I built for my bimac, I created an absolutly octopus proof overflow box, using black acrylic, sutting all my slits for the water to flow througth, then made a top for the box which slides in horizontally interlocking with the sides. You have to see it, but i dont have a camera, so for now your out of luck, sorry. I'll try to get pics soon.
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