I’ve found that adding liquid bleach does help some but after about 3 or 4 days, the pool water develops a slimey feel to it and it needs to be emptied out anyways. This doesn’t buy you much time between refilling.. I’m not 100% sure on this, but I would also assume that over time, the harshness of bleach could be damaging to the vinyl.

Here is my solution..

I picked up a 2.5 ounce bottle of Aqua Chem pool sanitizing crystals made especially for kiddie and wading pools. It’s made up of the same ingrediants that regualr pool chlorine is but in a much smaller dose. (I got mine at Meijers but if you don’t have these in your area, any large department store or pool specialty shop should carry it.) It costs no more than 5 bucks and it’s lasted me though two summers. (it requires that you add one level teaspoon of crystals to every 200 gallons of water.)
I don’t see a manufactures address, phone number or website on the bottle to pass along ~ Sorry about that.. But the name brand of it is Aqua Chem and it comes in a white bottle with blue writing on the lable and it has a yellow child proof lid.. It looks simillar to that of a medium sized bottle of tylenol.