I make lots of hypertufa pots. I don't treat them or seal them, but rather leach the lime out of them before I plant. After the initial cure, I soak them in a tub of water for 4-6 days, changing the water every day. You'd be amazed by the amount of crud that ends up in the water.
I do use a concrete sealer on concrete that I paint though. I use Behr concrete sealer. But I like the way hypertufa "breathes" so I don't seal that.
