Not sure if this is in the right section but I'm looking for input from you guys as to repairing a couple of cracks in our water holding tank at the lease. I've tried some of the cement repair stuff from Lowe's and some of the "as seen on TV" rubber compound stuff. Any other suggestions?

We used a can of "Great Stuff" gaps and cracks polyurethane-based insulating foam sealant that comes in a 16oz can on several of our concrete water tank. Used a wire brush to get a clean exterior service, placed provided straw up against crack and shot the expanding foam into it. After it has dried used same wire brush to clean up exterior. Has held for several years.

Most important thing is to get it clean and dry before you try to repair it.

Without a doubt.

I saw a procedure where holes were drilled into the crack(s) and plastic tubing was placed in them about two inches apart. The crack was then mortared with the tubes in place. Then starting from the bottom using a caulk gun and some type of resin, squirt it into the bottom tube until it starts to come out the one on top of it. Move up to the next tube and repeat. This was to fix a cement wall in a basement and may not be what you are needing.

This. Stuff really works as advertised.

1 part Portland cement, 1/2 part mason mix(type "s"),3 parts play sand and two cups of latex polymer. Mix in wheelbarrow and add small amounts of water till mix is like thick paste(not runny). Apply to clean and DRY surface using mason brush and smooth out by hand. Coating should be 5/8-3/4 inch thick. Coat whole tank if possible. Let dry for 2-3 days.
Surface must be clean and dry, also remove all algae from surfaces to be re coated. This will work much better than any rubber coating, caulk or spray foams. After filling, use some sort of algaecide in tank to prevent moss or algae from growing on tank walls. ALWAYS leave an escape limb or post in the tank for small animals or birds to climb on if they fall in the tank, this prevents dead animal water.
Good Luck

this no. 1

I've had great results with Quikrete Hydraulic water stop. Dries very fast