Bricks, Masonry, Asphalt and Concrete - cinder block fountain coverings

I would like to build a small fountain 6 ft sq out of cinder blocks, I do not want to use a rubber liner but would rather pour a slab of concrete then set the bocks on the slab. Then cover the sides of the blockes and the joint at the slab with a covering that I can paint later that would be waterproof. My big concern is where the blocks touch the slab where I would expect it to leak. I went to the local big box store but he had no ideas, any suggestions would be appreciated Ken

Here's a link that describes what you want to do:

http://www.aqua-fish.net/show.php?h=howtobuildapond

Not only can you expect it to leak, it WILL leak. If you insist on doing it this way, cove the base at least 2 inches, 4 is better.

What way would you suggest? Appreciate your comments

I'd go with a butyl liner. It would give me the flexibility I wanted for a custom size, rather than being limited by a preformed liner. Using a liner would certainly simplify construction and minimize concerns about leaks.