How can I get mirror to stay on bottom of swim spa?

[brownnugen]

I recently purchased a Swim Mirrorhttps://www.amazon.com/SwimMirror-HD-Improved-Training-Olympian/dp/B083MY3FPS/ref=sr_1_2?dchild=1&keywords=swim+mirror&qid=1624583897&sr=8-2 so I could monitor my swim technique.  When I placed the mirror in the bottom of my filled pool 12 foot swim spa and turned on the swim jets, the mirror started to float around and got in my way.

The company recommended using suction cups but I am reading the suction cups need a dry surface to stick to. Not wanting to drain my pool to try to make this option work, does anyone have a suggestion to make this work? 

[CanadianSpaTech]

Bean bags inside of zip lock baggies?

[Spatech_tuo]

Yeah you'd want the surface to be dry to initially stick the suction cups and then you can fill so I'd just go with and idea like that from CST until you do a drain down the line!