I recently found a bag of aqua soil that I bought some time ago...
And I was wondering if it's any good for bonsai. I have a few Rock Pine bonsais.
Did try to google something but failed...

Did someone try using aqua soil with regular bonsai?
Is it any good?
Is there a chance it can kill a tree?
Any thoughts?

What happens to it when it gets wet and freezes?

If it disintegrates and becomes a mush it will kill a tree.

I do not know the exact product so cannot tell what they are selling there.

I made an experiment last yerar. I had similar substrate from my old tank. Imixed in some regular soil into it and my trees did well. It doesn't hold onto much moisture. Maybe akadama will be better, it has similar properties. Do you really consider aqua soil as an substrate for trees? In Poland where I live it is quite expensive.