Viktor, I don’t want to jack your thread, but I have to ask- your leaking pond is fiberglass. So, if you don’t epoxy over the fiberglass, you won’t be able to hold any liquid. If some technology has changed, please educate me. I have to do the same on my fiberglass pond as well.
I consulted the maker of my tanks, Dolphin Fiberglass Products, Jack Broyl and he told me that i would need to remove, grind out the area until only clean original fiberglass is left, no lose fiberglass, no dirt or any other foreign matter. Then I must fiberglass over the cracked / separated area again. That's all. Pretty simple in terms of steps and logic.
He never said anything about the epoxy. I don't get your statement. Like... coat the fiberglass tank on the inside by epoxy? With my very limited knowledge, I don't know why anyone would do it and whether it is an established technique. Fiberglass is waterproof by itself. Plus the last coat of the fiberglass, the gel coat, is usually a special one, it contains a surfactant wax (and a pigment, if one wants some other color than natural fiberglass reddish-brown), which drifts to the surface during curing and forms a hard, smooth surface, additionally strengthening the waterproofing of the tank. But this is just an extra assurance, it is not really needed for a tank to hold water 100%, Jack says.
IDK if there are grades of fiberglass. Jack says I can use the standard fiberglass from Home Depot and Lowes to do my repair. Maybe there exists an extremely porous fiberglass or very thin (?) that would need to be coated and sealed but this is way beyond my humble knowledge.
HTH.
