drilling acrylic

Glass is tricky and waaaaay less forgiving. I drill tanks for shops in the area and I would tell you IME, I wouldn't attempt a glass cut without it being totally empty.
A. your shavings will def be in the tank and they are glass... they sink and you won't see them.
B. glass is super brittle and less forgiving. with pressure on it from it's inhabitants, it would put more stress on the glass. It can be done but I wouldn't recommend it.
C. If you "uh oh", your inhabitants will definitly be on the floor. Acrylic will crack if it's SUPER old and still give you time to grab a bucket or something to throw your "life" in.

Hope that helps.

 

Its been done several times I know of one for myself a 280 and a few for friends with larger tanks . last one was 2,500 Acrylic not glass but I have drilled several filled glass tanks But the guys where friends and they knew the risks. All went just fine a smaller tank like a 200 gal or less I'd simply drain it larger tanks thats not as easy to drain and get back up to speed .. As for glass in the tank ? All the chips simply are removed before the bulkheads are set in and then plugged inside or a valve is placed outside the tank then the inside Dam or barrier is removed . Anyone who has ever ran M/H have all had one to break and send glass to the bottom Its never been a real big concern, I recovered several pieces from the 180 I just had to break down due to a burst seam .

 

I drilled my stocked tank and had no issue at all. I put gaffers tape on the inside of the tank to prevent the pulverized glass from getting into the water. I drained about 5" of water out to be safe btw. I made sure the bit and glass were kept cool and went SLOW and did not push into the glass at all. I let the bit do 100% of the work. It took me about 15mins to drill through each hole, but it went well.

 

It can be done but there is a risk. I've drilled tanks and had no problem and I can tell you, with experience, I broke my personal tank. That was maybe the 3rd out of like 300+ and haven't broken one since but it could have been the temp, just the glass itself, the drill, the bit, me... anytime you drill you run a risk, more so with the pressure of water behind it. I have experience and it's not like I wanted to blow my own tank. It very well can be done though. Even displacin half your water down to the sump would increase your odds of success.
The best protection is to tape a bag against the glass you are drilling under where you want to drill to catch anything. I always over kill and always play it safe.

 

Absolutely correct, don't get me wrong. It is like russian roulette. It can be done with success, and seemingly "easy." I was lucky with my success, all things considered. Heck, to be fair, any success in this hobby, whether it be drilling or keeping the animals alive, is lucky. Being my tank is only 20G and draining 5" of water, meant I removed quite a bit of volume and pressure off the walls. Besides that, I didn't drill big holes and went extremely slow. Would I drill my 150G filled...not a chance in Hades would I do that.

 

anybody know what type of bit i can use to drill a 1.5in hole in my acrylic tank. i cant find abit big enough and i dont think a hole saw would work. maybe it will but i dont know.

 

You need to use a hole saw. Just take it slow so you don't melt the acrylic. That was what i did for all 13 bulkheads in my tank and sump. Just make sure you select the correct size.

 

GREAT thanks so much i have tons of them and was scared they wouldnt work.