Pool Weights for Inflatable

So this is a bit of a different question. I have an L shaped pool where I want to secure a volleyball inflatable net for my daughter. One side is next to the pool deck and the other side is a slope to the deep end. I have a vinyl bag that I could load up with rocks to secure the side in the pool but I'm wondering if there is a better product to keep it weighed down in the pool without risking my vinyl liner.

Thanks in advance