My neighbors do not believe me on Chlorine

[chem geek]

Using the numbers you provided, one 3" Tri-Chlor tablet will add 2.03 ppm of chlorine (FC) and 1.66 ppm of Cyanuric Acid (CYA) to the pool. If the pool lost 2 ppm per day, then you pretty much have to add about one puck every day and that means adding 1.66 ppm CYA per day on average. That's 50 ppm per month! Assuming that the chlorine is getting "used up" by breakdown from sunlight or oxidizing ammonia or organics, then each tablet causes a drop in pH of 0.11 and requires 13.1 ounces (weight) of Soda Ash (Sodium Carbonate) or 5.4 ounces (weight) of Caustic Soda (Sodium Hydroxide). I don't how much Borax would be required as I have not yet put that into my spreadsheet (found on the "Pool Water Chemistry forum in The China Shop forum, but beware -- it's not for the faint of heart).

Of course, some CYA is lost with splash-out (not with evaporation) and with backwashing the filter (assuming its sand or DE -- cartridge filters don't get backwashed).

But rather than just have theoretical calculations, let me tell you what happened to me when I first started with my pool 3 years ago. I was told by my pool shop to use Tri-Chlor tablets for the convenience (I was going to maintain the pool myself). I did this for one and a half seasons (about 7 months in a season) and found I could no longer maintain chlorine levels properly. My CYA had gone over 100 yet unlike your situation I was only losing chlorine at the rate of around 0.5 ppm per day (our pool has an electric pool cover which prevents a lot of loss). I was going through around one puck every 5 days in a 16,000 gallon pool. That's part of the reason I explored the chemistry of pool water and found out what all you guys on the poolforum already know -- too much CYA is a bad thing and liquid chlorine (bleach or otherwise) is simple, easy and inexpensive.

At any rate, the information about chlorine from different sources "sticking" or "staying" in one area of the pool is completely bogus. With decent circulation, the chlorine should spread around the pool fairly quickly, but to be safe you can always pour it around. The chlorine in the deep end will go through the floor drain and skimmer and come out in the shallow end where some jets are located. In fact, why don't you "prove" this to your friend by doing the following:

1. Test the free chlorine (FC) level at the shallow end.
2. Add a good chunk of liquid chlorine (or bleach) to the deep end of the pool (into the outward stream of a jet, if one is available).
3. Wait, say, one hour and remeasure the chlorine level in the shallow end of the pool.

I've never actually done this so be prepared to eat crow, but I suspect that at least half of the expected increase in chlorine level will be achieved in that hour. In fact, if you do this experiment, please report back to this forum so we can get some real-world experience on the circulation and dissipation of chlorine.

Richard

[gerri]

Also show you neighbors this:
http://www.poolforum.com/pf2/showthr...6809#post26809

It will aid in his "investigation"

[smallpooldad]

Thank you one and all.

I am going to print this out and give it to them.

As I tell my wife please do not ask me a question unless you are prepared for the answer.

[hulla]

Just let them use the pucks. Who cares?