Usually a concrete/gunite pool has plaster or a plaster/pebble mix or some sort of coating on top of it. Gunite by itself is porous. Is yours bare concrete/gunite?
(I do not think it is normal to have grit in the pump basket area, but my pool is gunite with a plaster finish.)
Edited to add--oops, I should have refreshed myself with your thread before replying. I remember now that you're the one with the pool that you believe is panted with some sort of decking coating. It is not normal to have grit in the pump basket area, and it sounds like the coating on your pool may be breaking down. But I am certainly not an expert on your type of pool.
(I do not think it is normal to have grit in the pump basket area, but my pool is gunite with a plaster finish.)
Edited to add--oops, I should have refreshed myself with your thread before replying. I remember now that you're the one with the pool that you believe is panted with some sort of decking coating. It is not normal to have grit in the pump basket area, and it sounds like the coating on your pool may be breaking down. But I am certainly not an expert on your type of pool.