As soon as any sort of dirt begins to collect in the rock, no amount of weed barrier under it is going to do anything. Dirt blows in, leaves fall and rot, etc. You will get weeds in rock.
I have a LOT of rock in my yard. I have found two things that work well at keeping weeds under control
1. Fire. A weed torch works great. Maybe not so much near a pool. Definitely not so much near your neighbors highly flammable decorative grasses.

. Also, if you have weed fabric under the rock, it will melt it.
2. Weed killer. I try not to use weed killer for two reasons. The environment and my dog. My dog actually likes to lick it. If I put down any sort of pesticide or herbicide, and let my dog into the yard, he will go over to the spot and lick it. What works (and what he does not lick) is vinegar. The good vinegar. This vinegar
Harris All Purpose Cleaner Concentrate fresh scent (case of 12) - kill 99.9% of germs, control the growth of mold and mildew, and infuse your home with a lovely scent with this disinfectant spray.
www.homedepot.com
This is not nice stuff. Do not inhale it, do not get it in your eyes, do not put it on your salad. Mix in a little Epsom salt and a drop of dish detergent and spray it on whatever you want dead. Preferably on a hot, dry day.