If you maintain your pool properly during the pool season and treat it with the right chemicals when you close it for the winter, tadpoles shouldn't be a problem because they can't survive in a properly chlorinated or brominated pool. If your pump should fail while you're away or you don't close the pool properly, though, you may soon notice hundreds of the larval amphibians, and before long, you may be kept awake at night by croaking. Shocking the pool will kill the tadpoles, but you can also be humane and relocate them.
In the lab, relocating tadpoles from one tank to another is considered difficult because small changes in temperature, pH or salinity can shock and kill them. Filling buckets with pool water, catching the tadpoles with a net and dropping them into the buckets is probably safe -- as far as the tadpoles are concerned -- but you aren't likely to catch all of them. To do that, you're going to have to drain most of the water from the pool.
Turn off the recirculating pump and place a screen over the drain outlet. Make sure the screen mesh is small enough to contain the creatures.
Allow water to drain until about a foot remains in the bottom of the pool.
Fill one or several 5-gallon buckets with some of the water that's left in the pool. Keep the buckets in the pool water to ensure the temperature inside the buckets stays the same as that in the pool.
Catch the tadpoles with a pool net and deposit them in the buckets. Once you've got them all, drain the rest of the water from the pool.
Let the pool dry out before refilling it to ensure that any eggs that may have been deposited on the sides of the pool won't hatch.
You may not have the time or inclination to save the lives of the tadpoles that have taken over your pool, and if not, you can kill them by introducing the purifying chemicals the pool lacks. The actual procedure depends on the type of purifying system the pool employs, but in most cases, it involves introducing the recommended amount of chlorine and then pouring in a shock solution to maximize free chlorine. The chlorine will kill the tadpoles, and once they are dead, they are easy to remove from the water with a net.