Welcome to the Forum!

I like Ben's suggestion of the floating ring around it.

I've always suggested tethering a floater from both sides of the pool, to keep it well away of the liner/ ladder. However, this can create an entanglement issue for swimmers, if the floater isn't removed prior to pool use.

Another way to tether it would be to fill a bleach jug, or similar with Sac-crete, add water and shake - the next day you'll have a liner friendly weight to secure the floater to, I made 6 of these last year to keep floating volleyball nets and water basketball hoops from straying too far (I gotta admit that making a weight this way came from Duraliegh [to the best of my recollection] ).

I'm VERY happy you care enough about the pools you take care of to come here and research and ask questions!