If chlorine is kept at proper level, is shocking ever necessary?

[Hubjeep]

Watermom,
thanks for the reply.

I stopped at Leslie's pool store for a water test. They said everything was fine and sold me a bottle of Ultra Bright. http://www.lesliespool.com/shopping/...ProductID=8174

I added about 20 ounces to the pool, the bottle says to let it filter for a few hours, then vac the pool. It is supposed to bring fine particles together that are too fine for the filter to trap.

The only numbers on the test sheet are:
Free available chlorine= 4 PPM
pH= 7.6
Total alkalinity= 100

It is a 25,000 gallon vinyl in-ground pool.