How do I keep a plastic pool ladder from floating?

If the tubes are hollow, get a bag of filter sand, and fill it with that. Works well on mine. (One 50# bag was enough for mine.) Also, fill the rest of the ladder with water before putting it back into the pool.

(You'll have to take off the top part of the ladder first, of course...most should come apart between the legs and the top piece. Then just pour the sand down the legs.)

If it's an A-frame ladder (free-standing, not connected to the deck), do a bag in each side.

I had this problem, but the ladder filled with water when it was placed into the pool and it helped weight it down. It still floated a bit, especially if anyone jumped or made waves in the pool. Perhaps make some type of a clamp that would connect the actually ladder to the deck? I dont' know that this is much help, but just know I had the same problem too. Our ladder since broke completely and we don't even use it.

A small boat anchor would work nicely

if it is hollow type. drill holes in it to let the water weight it down..