hey. I just did a google search and found "Grailcoat". grailcoat.com - described as flexible stucco. anyone ever try this stuff? site is interesting DIY

Do you have a pic of this problem child? Is it horizontal, vertical or both? While no cement based material is ever gonna' "stick" to rubber, there may be another way around it.

Glue some rocks with squirts of Great Stuff foam.

How about laying down some lathing, screen or rebar on the rubber, then hypertufa over that. I would think this would work just fine. Plop some stone onto the whole "mess" and it would look sooooo nice. Tufa will stick to a vertical wall as long as it has some lathing to hold onto.

Jo

Maybe that's why so many ponds are edged with flagstone in the classy mags & books.

Sue

I wired diamond metal mesh lath to the sides. I will apply something to that - should it be tufa or stucco or mortar? can any of these materials hold on the lath under flowing water?
I still don't know the difference in each compound. anybody ever worked with that flexible stucco grailcoat?

I once saw a faux rock product (maybe on a pond supply site)that attached to the coping and was ment to deal with your situation. But can't find the reference. Check out: Oase stone liner it has a pebble topping or edg-keeper at Aquaticeco.com. Both of these would go over your liner. The latter (edg-keeper you might be able to cover with your topping before installation. Also vanplant.co.nz. Figure 3 for a veneer concrete plaster for pond liners looks interesting.
I used a synthetic stucco on a block wall next to a garden fountain and have had real problems with algae discoloration, had similar problems with a concrete fountain.