Hi, I have a 26000 gal IG plaster pool with spillover spa already installed at the house I recently bought. There is a stainless steel rim over the spillover but at the side there is stone above the plaster, as shown. There is old caulk here with many gaps, and I think water is leaking through here. What is the best caulk to use here? Obviously ir would have to stick to metal, stone, and plaster. Any other tips about this would be welcome.