Quote Originally Posted by Deuce2
I'm new to this forum, so forgive me if this has been asked. I understand that everyone on here is stating that pucks keep adding to the total CYA, and that the CYA gets too high if you keep using pucks, and that is why everyone is using bleach. The problem with bleach is it is more manually intensive, and you can't use it when you travel for periods of 4 days or more. That is why pucks are great, you just put them in the inline chlorinator and everything is swell. Why hasn't any of these great chemists invented a puck that doesn't add to the CYA? Isn't it possible? I would think there would be a huge market for this if possible.
Deuce2,

Welcome to the forum! I must caution you that as my forum name (chem geek) indicates, I'm a bit of a chemistry nut, so I will try and answer your question non-technically, but if I fail I apologize in advance.

You are absolutely correct that it would be fantastic to have some sort of slow-dissolving source of chlorine that did not add CYA to the water. Unfortunately, the chemistry of chlorine makes this very difficult. It does not appear that using chlorine alone will do the trick. Now you might say, "well somebody figured out that combining chlorine with CYA produced a combination that was a slow-dissolving solid, so why can't someone find something else to combine with chlorine that didn't have CYA?" Unfortunately, no one, to my knowledge, has found this magical substance. No matter what that substance was, it would also get introduced into the pool water, but if such a substance were inert, then this probably wouldn't be a problem.

Today's modern technology with certain types of micronized drug delivery systems might be a possible solution where small "balls" with tiny openings could slowly release the chlorine content. Unfortunately, the purest form of chlorine itself is a gas and this isn't readily able to be contained in such balls so that's why you buy chlorine in liquid form where the chlorine gas has dissolved in water to form another related chlorine substance called "hypochlorite". So you might ask, "why not just put the liquid chlorine into the balls?" and the answer is that liquid in such balls would tend to leak out. In drug delivery systems, the balls tend to slowly dissolve in water or with stomach acid and relase their contents, but if you had chlorine in water (i.e. liquid chlorine or bleach) stored in the balls, then they would dissolve from the inside.

At any rate, micronized drug delivery systems aren't cheap and I suspect the cost for the quantities of chlorine needed to enter the pool would be prohibitively expensive.

By the way, there IS a very effective way of generating chlorine on the fly in your pool system. It's called a Salt Water chlorine Generator (SWG) and it essentially uses salt in your pool to generate chlorine, which when used up converts back to salt. You simply add enough salt to your pool to make this process work (typically around 3000 ppm total salt) and this is just below or near the level where you would taste the salt so most people don't taste it or don't taste it strongly. The salt also gives a silky feel to the water and the SWG is generating chlorine even while you are away on vacation! The only downside to the system is that it is initially more expensive and the salt cells need replacing every so many years -- this has improved recently as the cells used to degrade much faster and therefore was more expensive.

Richard