The aeration is what allows the carbon dioxide to be off-gassed, so it is an important part of the process. You can get a cheapie fountain in the pool section at almost any store that would work fine. You also can achieve a similar effect by aiming your return eyes toward the surface of the water so that it creates a ripple from your return jets.

Before you shock your pool, we really need to know if there is any metal content (copper/iron?) in your water, and what type of finish you have. Otherwise, Sherra's got you on the right track.

Janet