I've been following fly's advice too on this, Costco has some arm and hammer baking soda, 13.5lbs for like $5.50. I've yet to mine. Waiting till about a month before the tank is ready to acid bath.
I also went with the EMarco cement. $49.99 for 10lb kit. Heard some wonderous things about this stuff...like gravity defying matrix stuff.....
Personally, after reading on different ways to do this, acid does seem to give me an piece of mind, cheapest too. Is that grave to shallow? What if it floats back up? You sure your dogs can eat that much? Acid? Yeah I'm good.