Hi help, Nenella and Johnblagg
I used to use a thick-ish metal pin that I used to heat it in a flame and pierce with that but it always leaves ugly black burned plastic around the holes so this time I used my husband's drill. This pot (Tupperware) was a lot thicker than all the other actual flower pots so that's why it was harder to drill but the holes are nice and clean so it was worth it. I am sure it would have been even more difficult and a lot messier with the hot metal pin thing.
In regards of the stability of the plant in the media, I find that because the pot is taller then before and that long root is stretched properly the plant has more stability than before. So far no Hydroton floated in order to disturb the roots as I soaked them a lot. Hope it stays that way, I'll just have to wait and see what happens. And I checked, the root is above the water line. I was careful when I poted to place enough pellets above the holes level before I placed the plant inside.
PS Nenella I simply love the picture of that cat. Is it your cat? She is purely delicious