Anyone have any suggestions?

We sealed our concrete coping with Stonetech Color Enhancer Pro. It seals great and does really enhance the color, but it is horribly expensive (around 60 bucks for a quart). I could not find a local place that sells it and had to order it online. Lowe's carries the Color Enhancer, but not the "Pro" version (Color Enhancer is for indoors, Pro for indoors or out).

I forgot to add that you can try Thompson's sealer on yours to see if that helps. It's a penetrating sealer and is pretty cheap and widely available. The PB used it on all of our stone work after it was installed.

I'm not sure that person you spoke with knew what they were talking about, or maybe they didn't understand that you're sealing stone. Marine grade polyurethene is for wood. Thompson's is about the only thing you will find locally unless you go to a specialty stone or tile shop, the chain stores just don't carry exterior stone sealers like you're looking for. Thompson's can be used on surfaces that get wet (like a waterfall), but it's not as effective as pro sealers.

By the way, in case you are calling/ asking around you're looking for "sealer", not "sealant". Sealant is the term for caulk-like material that goes into joints.

Just my 2 cents, but if you're looking for a "Marine" grade product (which btw I think is sounds like a good idea), have you tried calling around any local Marine suppliers? I'm not sure if there are any in your area, but I just thought I might mention it. If there are any boating dealers locally, you could call them and ask them for local marine suppliers.

Good Luck!
-Renee

I am having this same problem. I have a swimming pool with a beach entry that is natural stone. The stone is being turned into sand at the bottom of the pool and impossible to keep clean. Did you discover the best sealer for your waterfall?

I had a pool put in 20 months ago with a mix of red flagstone, and a beige to white stone. The red stone started melting and flaking away. It was almost immediately. I tried a coulple of different sealers, but it didn't help. I was finally told it was from the salt system. For now I will go back to chlorine. Eventually I will have to replace the stone with something man made. The salt also rusted my patio furniture and put rust stains on my deck. I didn't realize this virtually harmless product that you use at your dinner table, could cause such destruction.

I am a waterproofing contractor in the mid atlantic. What you need is a product called siloxane. It comes in a five gallon bucket and can be applied by brush or hudsen sprayer. They do have a web site, just google siloxane and find a distributer near you.

caulkusa, would you use Rainstopper or Silox seal on waterfall rock? We have switched back to Chlorine but want to seal rocks against further deterioration. Thanks!

We have same issue and red flagstone that has flaked off as well, seems like every pool maintained person says not to seal grotto/rock but what to do with the sand falling off and making a mess 🙄