I noticed a small, 8 inch long, 1/4 inch wide gap under the granite ledge of my spa spillway. The gap is between the top of the wall tile and the bottom side of the granite where it hangs over the pool.

The pool is an in-ground gunite approximately 20,000 gallons with a raised spill-over spa.

There is also a narrow gap or crack between the top of the plastic waterfall opening (shear descents) and the bottom of the brick coping.

Is there a gray colored caulk made for pools that I can use to fill these gaps. If so, where do I buy it? I bought some 3M pool caulk/sealant at HD (its in a tube) but it is too liquid to use on a vertical surface.
Thanks.