View Full Version : plugging up glass holes

07/07/2010, 12:46 AM
i have two holes (one is 1.5" dia. and the other is 1.75" dia.) on the bottom of my glass tank. they were factory drilled. but since i am going sump/fuge less, i would like to plug these holes up. do i first glue the acrylic pieces to the glass with some kind of adhesive then silicone the edges? what can i use to glue acrylics to glass? thanks

07/07/2010, 04:13 AM
I personally used some 3/8" Lexan on a 1.5" dia hole on the bottom of a 75 gal. Glued inside the tank. Just used Silicone. No leaks or problems experienced. I made the disk ~ 4" in diameter.
Please note. What worked for me may not work for you. Different adhesive/techniques may affect the outcome.Please seek advise from others here also. I HATE WATER DAMAGE!

07/07/2010, 05:12 AM
You can always install a bulkhead in each hole, with a threaded plug in it so it can be undone later if desired.

Otherwise I'd just silicone a piece of *glass* over the holes. I just don't trust the acrylic-to-glass bond as well as glass-to-glass.

07/07/2010, 06:14 AM
I would use bulkheads and plugs. This way if you want to add a sump down the road, it is easily reversible.

07/07/2010, 06:36 AM
if the tank is glass i would get 2 small pieces of glass in silicone them over the holes. silicone does not adhere to acrylic!

07/07/2010, 06:36 AM
The bulkheads will allow you to potentially re-use those openings in the future. But - if that does not fit with your ideas for the tank - definitely use glass - preferably the same thickness, but not an absolute - just don't use thin "window pane" glass - and clean the tank bottom and the glass patch using dentured alcohol - or better yet, acetone on clean dry paper towel.
Note: get teh glass patch made so that it is larger than the hole by 50% or more. Have the glass shop "ease" the edges - which is a little sanding of them, so they don't cut you while working with it - or while cleaning in the tank in the future.

Best 'o luck!


07/07/2010, 06:49 AM
I would absolutely use bulk heads. There is no way I would trust patching a glass tank.

07/07/2010, 06:55 AM
Well - if you own a glass aquarium - you are trusting a more critical connection than a glass patch. Think about it....all the panes of glas in a tank are hekd together by the silicone. NOT the trim around the tank.

So - when using a glass patch, you actuall have a stronger "joint" because you are overlapping the glass (perhaps for a couple of inches beyond the hole) and have MORE surface contact area than is used to join the glass panes on your tank. Make sense?

I have done this hundreds of times. NO issues....NO leaks....


07/07/2010, 09:20 AM
I agree with bulkheads, but not the plugs (unless you put a plug on both inside and outside). Install ball (true union would be ideal) or gate valves. While you right now have no use for those, it would mean draining the tank or a huge mess if you ever chose to use them for another use.

07/07/2010, 09:45 AM
Bulkheads do offer more future versasatility OP. Cost is a little more initially, but not a lot, depending on hole size.


07/07/2010, 09:55 AM
I was assuming the holes were under a RR overflow. Yeah, if the holes are just on the bottom of the tank, plugs wound not be the way to go. The glass patches on the inside held with silicone would be the best bet.