Help with weighing down ladder!!

Hi Everyone! I am new here and am a newer pool owner. We have an above ground 15' round pool, with a fan tail resin deck on one side. We have a ladder that is attached to the deck via screws and sits down into the pool. The ladder constantly floats up and pops the screws out of the deck, we have been told to weigh it down with tube sand, however we don't want to put sand in our pool (for obvious reasons) and there really isn't anyway to attach the bags to the ladder or put them inside of it. Also tube sand can only be found in this area (MA) in the winter and we didn't purchase any. I do not own a lot of tools, I am handy but do not have the right tools typically to "build" things. i thought of pouring cement into half gallon milk jugs and tying them to the ladder with nylon rope, I can seal the jugs with some water proof silicone. Does anyone have other suggestions, or perhaps reasons why this won't work?

Get 2 jugs of premium milk (in this area, it's Mayfield, but what I want is the jugs, not the milk) that comes in heavier jugs.
Get a bag of filter sand. (or really, any dry sand)
Fill the jugs with sand (using a funnel, after you drink the milk, and rinse the jugs)
Add a cup of water with a tablespoon of bleach to the jugs.
Cap the jugs and time them to the ladder
Don't worry about cement or sealing the lids, unless your kids will fiddle with them.