Advice? Drilling a tank/sump

I was thinking about adding another external pump to run a manifold and a external skimmer so I can have more water volume to the man tank. So with this has anyone drilled a tank with water in it. If you were to block off the water to the section that you were to drill or just use an internal pump.
The only reason I ask I got a ETSS downdraft skimmer.

 

Love that skimmer.

I personally used pvc to plumb the etss skimmer from my nondrilled sump it worked very well.

 

I think its a really crazy risk to take drilling a tank that's already up and filled with livestock.

 

It's a 150 gallon used as a sump only around half full water

 

when you drill glass, you need water to help keep it cool. How are you going to do that with it upright?

 

There is now way in hell I would ill a tank with water in it. Half full or not.
Like Craig said. Jhow you gonna keep water on bit?

 

Garden hose and floor drain., @AdamLawrence isn't there a floor drain a few feet way? You could squeegee the water to it. I have some 1/4" hdpe you could put on inside to slow water down and give you more time to get all the way through.

 

What would you do about the glass shards? Just curious wouldn't it be hard to get them all?

 

I have done this once although I knew it was risky. I put a giant tub under the edge of the tank and had the tub filled half way with water. Then ran a small pump from the tub connected to tubing to run water over the drill bit. The water would run back down into tub. To avoid the glass shavings going into the tank I taped a plastic container over the area I was drilling. I did lower the water volume in the tank below the area I was drilling and it was only a 20g tank. If possible tho I would always recommend doing it empty.

 

I like everyones input think I'll try a mag 18 or I'll run a hose to my external pump make it act like a syphon