problems with chlorine

[odbob]

we have enjoyed our pool for some years, but over that period we have some difficult times caused directly by the use of :-

Shock chlorine, this chlorine is contained within a powder and that powder does not disolve in water, hence we are left with a grey matter all over the floor of the pool. Tried mixing this thoroughly in a small container and no matter how much mixing, the grey matter remains and settles out.
If we want shock now, we use liquid bleach from the local supermarket.

Question :- is there a shock chlorine in another form whereby no residue is left behind ?

Stabilsed chlorine, the cyanoric acid builds up in our pool to the extent that we have to change the water after 4 years use, this is a liner indoor pool.

Question :- is there another way of routine treatment without the use of cyanoric acid.

Regards Odbob