How do you keep ducks from swimming in your outdoor pools?

There was a product called "no more ducks" that broke the water tension that enabled ducks to float. It was withdrawn from the market 12 months ago and has not been sited since. Does anyone no why? It was very effective in keeping the ducks out of the pool as they could not get comfortable in the pool and flew off.

new answer:

Loud sudden noise, something to irritate or make the birds uncomfortable being there. Once their offspring have hatched they become imprinted on that body of water and will come back for years rearing their young. It takes persistance.

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Several years ago a pool company told us to buy a alligator blow up and float it in the pool, WE HAVE HAD ZERO DUCKS SINCE THEN. WE TIE IT TO THE SIDE AND ALLOW IT ROOM TO MOVE AROUND. THIS WORKS.

No more ducks is still available..... at least here in Australia. We also have a new product called Duck Solution (ducksolution.com.au) and it is used if the ducks are hanging around poolside and fouling the area. Once they got a taste and smell of it they left. They have not returned. I think they went down the street. Anyway not here.