If you’re talking about the air stone, it won’t hurt as far as I know! Get some more oxygen to the roots! If you plan on adding air stones in the future I would drill an extra hole next to the drain hole for the tubing.
Grow buckets have the tube from the bottom up to top of pot right has the green level shower in the tube. If it is what I am thinking I don’t have to drill another hole u should be able to run the air line right down the water level tube how has all been it’s been a long long time of me being on here surprised I could log into it. Lol. @LoCoRocK @pptrsha1 had to pop by and say wazzup
You could run it down the filler tube however it would restrict the level indicator.
I wanna say mine has quite a bit of play between the tube wall and the bottom base of the checker part. I wanna say a quarter tube should slide down I havnt used mine but for 1 grow lol. It was right towards beginning of me growing I could be wrong lol. It’s been a while even seeing my grow buckets. I went coco and never looked back to them.