Took the dremel and built an external overflow with fish still in the tank

[Lordhelmet]

glad this thread came up since iv'e been looking to drill my 75 glass tank.

[sublime250]

I have an overflow box in the corner of a 120 gallon tall oceanic.

It has a 1" bulkhead and hole done on the bottom glass already. Can i enlarge it without cracking the glass? any thoughts ideas?

I can easily drain all water from the overflowsection...

[Stile2]

It would depend on if the bottom is tempered. If it is tempered you can not drill it in any way, it will crack into thousands of pieces.

But if is not tempered you should be able to drill it.

I would suggest a Rotozip with a carbine tile bit. I used a spray bottle full of RODI water to cool it.

Good Luck
Keith

[sublime250]

If it is already drilled, wouldn't that rule out it being tempered glass?

[smcnally]

Originally posted by sublime250
If it is already drilled, wouldn't that rule out it being tempered glass?

Nope. I just bought a 125 Gal Reef Ready AGA, and right near the drilled holes there is a sticker that says "This bottom is TEMPERED GLASS for strength and reliability DO NOT DRILL"

[Stile2]

smcnally is right. What they do is drill the untempered glass then have it tempered for strength. You have to make sure it is not tempered. If it does not have a label on it, I would call the manufacturer.

Keith

[Leopardshark]

I wouldn´t drill it.
I´d rather drill another hole, but first be sure the glass isn´t tempered.
Marco

[sublime250]

Any reason why?

[DaveBrader]

I am getting ready to do some custom drilling on a new tank. Nice to see it is not too difficult to do.

Dave

[Stile2]

Jeff,

Since Leopard isn't getting back right away. I'm not sure why he says don't drill bigger but just a new hole.

If you do drill what is the plan? And what is the goal?

Keith

[sublime250]

The plan is to increase drainage from the tank. I wonder if I just put a reducer from the 1 inch pvc bulkhead to a 1 1/4inch pipe if I would get increased drain capacity or would this just create a bottle neck effect and get the same amount of drainage?

So i would have a 1 1/4 inch stockmen's pipe reduced to 1 inch for the bulkhead through the tank then bring it back up to 1 1/4 inch immediately after the bulkhead...

[Leopardshark]

I wouldn´t do it just because I think the possibility of a crack is bigger if you try to drill a bigger hole because I think the glass is weaker in that area.
Please correct me if I´m wrong.
Marco

[Stile2]

I believe that the 1 inch bulkhead would create a bottleneck.

I am not sure about the idea that the glass would be weaker at a current hole.

But if you have the room to drill a new hole it might be easier to get a nice round hole. Just an idea.

Keith

[Nem0]

This thread is great. Thanks for sharing the info.

My question is, will there be any concern with the glass powder or the whitish stuff falling into the tank and get mixed with the tank water? Any thing to worry about?

Regards,
Dave

[Leopardshark]

The whitish powder is nothing to worry about. SOme of it got into my tank... no problems at all.

[Stile2]

Same here, I pretty sure it just fell to the sand and combined with it.

Keith

[DHyslop]

You've sold me. I've got the quarter inch glass pieces, I borrowed my dad's Dremel, and I'm going to pick up the diamond bits at Lowes this afternoon.

I have a question about building the external box, however. When I built the internal box for another tank, it was recommended that I have a 1/16 to 1/8" gap between the glass pieces and the side of the tank so there's some room for the silicon to wrap around the pieces.

Since this is external and needs to be a bit more exactly I assume the pieces should directly butt together? Since this is a real load-bearing application I just want some tips on the siliconing. Should I lay a bead on one piece of glass, clamp the pieces together, and then smooth it into an inside fillet?

Thanks,

Dan

[Stile2]

I first clean all pieces of glass (where the silicone will be) with rubbing alcohol and a razor blade. Then put a oversized bead of silicone on the edge of glass and set in place.

On this project since it was a set up tank I used cargo straps to keep the box on (and I per built the box).

On my new project (the tank is not set up) I used a bit more regular method. I used tape to hold the pieces in place.


I used quite a bit of extra silicone and smooth out the inside seams into nice radiused corners. I figure I can cut off any extreme excess silicone with a razor blade.

I put the last piece on and weighted it down.


I try to get the seams to look as close to what the seams look like on my tank as possible.

Sorry about the rambling, I had a really late night.

Keith

[DHyslop]

Thanks for rambling, Keith: it makes for less reading between the lines

...off to drain the tank!!

Dan

[DHyslop]

Keith--

How close do your holes get to the top of the pane of glass? From the pictures it looks like ~ 1/4"?

I've got my tank drained and my return drilled, but I figured I'd spare my neighbors the whine of the Dremel during the night. I'm was very tempted to cut one long hole for a bit more flow like in some of the other external overflow threads, but I'm worried about the structural integrity. I've read about at least one tank exploding after doing a big hole for an external, so I'm probably going to stick to the slots like you did.

Did you ever put a new pump on? If you did I'm curious what your flow rate is vs the height of the water above the bottom of the slots. I may extend my slots a little further down if I know the water level will still be above the outside trim.

Thanks,
Dan

[Stile2]

Hey Dan,

Sorry about the late reply, got in at 3 am after a night of poker with the boys.

My slots are about 1/4" from the top. I never did put on the new pump as I am building a new bigger tank (click the little red house to check it out). As long as the bottom of the slots is slightly above the bottom of the trim, you should be find.

Right in the 29, the water is about 1/4" above the bottom of the slot but I am only running a Rio 1100 with about 3' of head, so 230 gph. But I still have another 1/2"-5/8" above that, so I think that I could go with a lot more gph.

Post some pics along the way. You are more than welcome to post them here, or post a link to a new thread. Which ever you would like.

Keith

[DHyslop]

Thanks. I don't have a digital camera, but I might take some old-fashioned emulsion pics and scan them in when I'm home for the holidays.

Its an Oceanic 75 gallon tank, but its FO so I'm not too concerned with flow (I've been running a mag 7 and when I do a "bucket test" I'm getting around 380-400 gph).


Thanks for all your help, by this time tomorrow I may be ordering a new tank!

Dan

[DHyslop]

It is done. Waiting for the silicon to dry.

The 5/16" glass on the 75 is a real pain to cut through! I cut the grooves and made the starter holes using the ball tip yesterday and I spent 8 hours today with the taper bit cutting out the slots. I am so glad that is done!

My slots ended up being a bit more than 1/4" wide, probably around 5/16", with the area between correspondingly smaller, ~ 3/16" (lack of skill). I'm not too worried though because of the glass thickness.

The problem I do have is my fiancee and I are going out of town for about three weeks on Thursday. I don't want to fill the tank up and have the pane burst the day we leave. My LFS has warehouse space so maybe I can talk them into letting me wet test it there for the better part of a month in exchange for some beer

Dan

[Stile2]

Congrats, I agree with the not wanting to water test while your gone.

Let us know how it goes.
Keith

[T1adler]

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