The most obvious solution is to eliminate any surfaces of dissimilar metals.
Plating, enameling, painting, replacement with non-metallic, etc., are possibilities.
You can't mix copper and any other metal.
If the pool is aluminum, no metal except aluminum in the pool.
If the pool is steel, no metal except steel in the pool.
Proper grounding can make the corrosion worse!
You could try applying a strong negative bias onto the pool, like -30 V DC. But getting rid of the all but one metal is the only real solution.
