I had this problem last year and was able to patch it up enough to get some water from the waterfall but this time the flexible hose broke in two and tape won’t hold it. Thinking the water comes out in such force it blows the hose apart. I can’t even imagine how I’d ever take all those rocks down and replace the entire hose.

So I’ve Googled my head off and found a solution that might work that involves fitting each end of the hose into a piece of flexible PVC that fits tightly then using marine epoxy putty to seal it and allowing it to cure for a few days. My question is: What size flexible PVC should I get? My hose is 3/4”. TIA.

There should be fittings available for your existing hose.

An internal "barb" type fitting with exterior hose clamps should work fine. Likewise, there should also be external fittings that would work, and have the additional advantage of NOT reducing the ID of your hose.