The aquarium I have has a sticker on it saying it can't be drilled. I've been looking at the overflow pumps that you can set up a sump with, does anyone have this, recommend it? I've heard some youtube vids say they have potential to flood, just want to see if anyone has this set up.
Punkin eater
I don't call them overflow pumps although I have seen designs referred to that way.
Add on siphon overflows come in many configurations and each method has very specific requirements and problems.
Personally I can't stand them. I've only used a few and they always kept me up at night worrying about them.
Note: if the tank is plastic it may be able to be drilled, tempered glass can't, regular glass can, but it's likely you'll break a tank and have to buy a new one. Get one that's already drilled or has an overflow built in.