Water Tubes will keep the cover from sinking into the inground swimming pool. Tubes should ideally be touching each other end to end (around the pool). They will not split, rip, puncture or break. Installation is easy! Simply fill to 50% capacity (to allow for expansion of ice) with a garden hose and close the leak-proof valve.
I bought a bunch of these to weigh down the cover for my pool and I do not have any issues with these. The price seemed good compared to other retailers.