I have a small pool (10' diameter by 30" deep), and my pump doesn't have very strong suction, so I bought a Micro Vac, made by MP Industries. It works great, and since it attaches to my garden hose, it replaces the water I lose due to evaporation.
It could also attach to a spigot plumbed into the pool's plumbing, for those who would prefer not to add cold water into, say, a hot tub.
http://www.mp-industries.com/products2.html
The picture shows a leaf bag attached to the Micro Vac; mine came with a cloth bag that does a great job of catching the sand that accumulates in our pool.
It could also attach to a spigot plumbed into the pool's plumbing, for those who would prefer not to add cold water into, say, a hot tub.

http://www.mp-industries.com/products2.html
The picture shows a leaf bag attached to the Micro Vac; mine came with a cloth bag that does a great job of catching the sand that accumulates in our pool.