maximum (sensible) weight for a 3ft punch bag?

[Jimanuel Boogustus]

I recently bought a 3ft punch bag with the intention of turning it into a sort of punch bag/ wrecking ball hybrid. The bag currently weighs in at roughly 20 Kgs and I had bought a cheap 15kg bag of play sand to weigh it down further. The bag still moves around a little too much for my liking (a relatively light jab will still send the bag 40 degrees away from me) so am thinking of putting a second our even third bag in.

My question though, is had anyone here find it impractical to load up a small bag in such a way?

Diyes anyone have any recent experience/ opinions of a 3ft bag??