Hello guys.

I wanted to move my pomegranate tree in a pot to move it indoors before the winter.
I went to the local gardening store for a bag of perlite for my potting mix, but they weren't selling any. The lady who works in the store told me I could use those water crystals instead, they would have the same effect.
But when reading the instructions on the pack I think she is misinformed, as I would think those crystals would reduce the drainage capacity by just swelling and retaining water.

Can you guys please help me out? Googling doesn't really make me any wiser. I really don't want to harm my tree.