Attach a Betta Log to side of tank?

My betta - Jaws loves his floating log. It's his safe place. But with the current in my 29G that log gets tossed all over the surface of the tank.
So I'm wondering what are safe materials to use to attempt to attach it to the side of the tank?
Right now I'm trying a suction cup with a clip attached that came with my gravel vac since I have an extra one. The clip part is not quite big enough for the log to be 100% secure in the clip...but I'll see how long it lasts.
Any other ideas?
I like the suction cup idea....just don't know what material to use to attach it to the log. The tank silicone I have doesn't seem to hold forever so I'm hesitant about using it.

 

You could attach the clip with aquarium silicon as its a sealant it should be sticky n you could pre stretch the clip on a coffee mug or something plastic will stretch eventually

 

Can rubber bands go in fish tanks?

 

They can as long as they're not coloured I have one holding my anubias to some wood and I know other members have used them

 

I take some string or fishing line and tie it to the log, around the open part. then I tie something heavy one the other side of the string. that piece hangs outside the tank. hope that's explained well enough.

I usually put them in the back so you can't see the string hanging out of the aquarium.