I like to seal mine with a wet look sealer...I use the Quikrete brand it really makes the flagstone show its colors...Also with a salt pool it's just a good idea to do it...

Here are some pics of our Oklahoma flagstone. We will be powerwashing it this weekend, cleaning and scraping, and sealing.
When it is wet, is when ours becomes really soft and sandy. Here is a pic where someone gouged the stone by dragging the umbrella that fits in a hole in the decking.

Here are marks made by the Polaris.

Deep end coping erosion caused by hands grasping wet coping.

Close up view

Erosion caused by water runoff

Erosion caused by pool and sprinkler run off

WOW this scares me....I have heard Deck O Seal is pretty good... I don't like a glossy look, want it to look natural... any thoughts?

Try both on a piece of leftover stone and then decide which finish you like....

If you have a stone yard within decent driving distance, see if you can locate Techniseal WL4 Protector sealer. It is deep penetrating sealer with a satin finish, so enhances color but not a shiny look.
It's not the cheapest thing you will find (like at box stores) but not the most expensive either. This was priced at $58 a gallon, which isn't too bad. We will do our moss rock as well. It will keep the moss from growning :( but I can't have this erosion anymore.

Techniseal also makes a penetrating sealer that is no color enhancement so you it will look like dry rock. I forgot to mention that, since we are doing wet look without the shine.
If you are not in a rush, I will post picks as soon as it is done so you can see what satin finish looks like. Sealing should be Wed or Thurs if it does not rain.

I meant to say color enhancement, not no color enhancement. However, today, the talk was, techniseal would not be good for my sandy stone but a stone sealer by Prosoco, called Sure Klean Weather Seal Siloxane PD. Totally penetrating, no stone enhancer, so you wont know it is there. It allows moister out but not in. It lets stone breath, so to speak.
Looking into it more before we decided.

hey zookeeper, what did you decide to do with your coping and what product did you use on yours. i see the product you have listed above but trying to decide on 3 or 4 i have found on the internet.

Thanks!

We relocated to Houston and had the same problems with our flagstone pool coping, it was flaking and leaving a sand residual in the pool. My pool cleaner referred me to a company called flagstone sealers. They came out and cleaned and sealed the flagstone using dupont saltwater resistant sealer, took about 2 gallons. The sealer looks like milk. Its been three years now and the flagstone looks great. Sorry I am not a DIY .

Doris