frogs for slugs and snails

i have a duck deficiency!! but dont want any ducks, as my garden is not duck friendly. so i am thinking of investing in a smaller pool for froggies. i have an old pretty big fish tank. last year i left it out and it filled up with rain and i found a frog. but i had to move the tank. but because of the slugs, im thinking of putting it back, but what is the best kind of habitat that frogs like. i know they don't live in water all the time, so just wondering what to plant near by so to allow for its living space.

thanks

Frogs are wonderful helpers in the garden.

Are there any natural water features in your vicinity? Ponds, lakes, streams, etc.?
If so, observing them should help point out what local plants provide a haven for the local frogs.
It may also become a great resource for collecting the desired plants. Most waterside plants transplant well.
As close to their natural habitat you can get, the happier (and more prolific) they will become.

Besides water and waterside plants, frogs love rocks.

Frogs sit atop them, looking for prey, and hide under them when they are the prey.
They need hiding places for both the full grown adults, and the smaller ones...including the tadpoles.

I think toads would be much better suited for living in a garden. Frogs have to be moist all the time and are usually high strung. Toads on the other hand, only need to be in water for breeding and have mellow personalities. If you have toads, be careful when digging in the garden because they like to burrow and you can kill or injure them with a spade or hoe.
Someone could make a very good living by raising them by the thousands and marketing them as garden helpers.