There are a million chemicals available for pools. IMO, most aren't needed.
Now to the disappearing chlorine. Chlorine is used up fighting the nasty stuff in the water or the sun will break it down. If your pool is crystal clear then it is probably the sun breaking it down during the day. If the pool is green or cloudy then the chlorine is probably being used up fighting something in the water.
Next time you go to the pool store, ask for a printout of the chemical balance of your pool. Post the numbers they give you here. We can give better advice knowing those numbers and knowing the type of pool and equipment you have.
Pool Slave wrote:Oh, I have and use test kits, but what's a person to do when the 'experts' repeatedly test your water and say you need this, that, and the kitchen sink? I'm a bit at their mercy - after all, they're the experts, right? sigh.
Anyway, for what it's worth, the CYA level is about the only one that has remained relatively level (but certainly something to keep an eye on). After I shock (Smart Shock), all levels are fine (including pH), but within 36 hours the chlorine tanks.
Water's looking good, though (for the moment). Su-weet...gonna be 99F today.