Backyard Aquaponics
A place to discuss aquaponics

Definitely an angle grinder with a ferrous metal cutting disc. Melts a bit where it cuts, but you just remove the burrs abs the cut is smooth and clean.

I've cut two of them. I have a dual saw with counter rotating blades and id one with it. The other was done with an angle grinder. The dual saw was far better than the angle grinder.

It has been a while since I cut my IBC, but I'd I recall, the only thing I did not like about using a jigsaw on the IBC was that it flexed with the movement of the jigsaw. I think I resorted to the grinder on mine.