We bought (on sale and now I know why) this lovely fountain and spent some time installing a pump; however, the stone is porous and lets the water out very quickly. What would you recommend to seal it?
There are products on the market that you can use to seal it. Check out Lowe's or any big box store that carries paint. You just brush it on, usually two coats, and it seals the surface. It isn't expensive, unless you need it to be safe for fish. There is a special non-toxic product for fish ponds, and it is expensive.