Look at Max ACR http://www.ebay.com/itm/EPOXY-RESIN-AQUARIUM-TANK-PONDS-CONSTRUCTION-1-5-GAL-/310075939459 for the sealant. Easy to use, goes a LONG way and they sell pigments to add to it so that you can make it whatever color you want. I used 1 1.5 gallon kit ($88) to get more than 7 coats on my 500 gallon that's been up for over 3.5 years now with zero issues.