Adding Chlorine Every Day

[jhk49]

I am a relative newbie to this site. Ben helped me the first time with getting my water chemistry correct. Since then, I have been testing everyday but I find that I am continuously adding chlorine on a daily basis. Here are the particulars:

I live in south Georgia and the pool (25000 gal) is in full/partial sun. It has been hot and dry here. Mid 90's each day.
With direct from the Ben the PoolDoc, my water chemistry was balanced on Saturday, 7/2/11 ...
7/2/11 pH 7.2, FC 5.5, CC 1.0 and CYA 80 ppm
7/3/11 pH 7.1, FC 0.5, CC 0.5 .... added 1.42 gals bleach and 2# borax
7/4/11 pH 7.2, FC 2.0, CC 0.5 ..... added 1.42 gals of bleach and 1# of borax in the morning
7/4/11 pH 7.3, FC 6.5, CC 0.5 .... pool was used heavily during a cookout
7/5/11 pH 7.2, FC 1.5, CC 0.5 .... added 0.75 gals of bleach
7/6/11 pH 7.3, FC <0.5 ............. added 2.17 gals of bleach
7/7/11 pH 7.3, FC 2.0, CC 0.5 .... added 1.42 gals of bleach
7/8/11 pH 7.2, FC 1.5, CC 0.5 .... added 1.42 gals of bleach

That comes to 1.43 gallons of bleach per day = about $2.50 per day, is that normal?

Secondly, how often shall I shock the pool? Or, how do I know when?
How much bleach do you shock it with each time?

Thanks.
jhk49

[Watermom]

Your chlorine levels are way too low for your CYA level. I'm surprised you don't have a green pool. Take a look at the Best Guess Table in my signature below. With a CYA level of 80, your chlorine level should be between 5-10 ALL the time. When it dips below 5, then you risk an algae bloom.

Actually, people who have high CYA pools typically can go a couple of days between bleach additions. I think what may be happening in your pool is that your cl level dips low and a little something may start growing even though you can't see it yet. That uses up the chlorine and then you need more.

My advice is to shock the pool up to 20 this evening after sundown. An hour after adding the bleach, test the cl. Tomorrow morning, test again within 2 hours of sunup. If you have lost more than 1ppm of cl, then you should run shock levels again tomorrow and repeat the overnight test. Continue this until you can pass the overnight test. Then, you can let the cl drift down but keep it between 5-10 all the time.

You shock the pool when you have a CC greater than 0.5 or if your chlorine has dipped too low as a "just in case." As stated above, shock level for CYA of 80 is 20. You test the cl and then add however much bleach you need to get to 20. For reference, in a 25K gallon pool, each 1.42 gallon jug of 6% bleach will add 3.4ppm of cl. Each quart will add about 0.6ppm.

When all things are good and you aren't having to shock, I don't think adding 1.42 gallons per day is all that much for this big of a pool. I have a 13K gallon pool and I typically add 2 or 3 quarts per evening.

Hope this helps.

[jhk49]

I did as you said and shocked the pool yesterday ..... early this morning, it had lost 1 ppm (down to 19 ppm). I checked the chlorine again this afternoon. The pool had not had any use and it was a hot and sunny day. The temperatures were about 97 degrees F plus very humid. South Georgia is warm during the summer.

The chlorine level (FC) had dropped to 8.5 in just that one day. That seems to me to be quite a decrease. I am running my pool pump/filter about 8 hours per day.

As to you saying that 1.42 gallons of bleach per day would not seem that high to you, the cost would be about $2.50 per day during the season. How much do you add per day to your pool in the "winter months". The reason that I am asking is to calculate what the cost savings might be for a salt system. I wonder if the power used by the salt system eats up any cost savings in chemicals?

JHK49

[aylad]

You'll find that the higher the chlorine level, the more you'll lose in a day. You may have gone from 19 ppm to 8.5, but tomorrow you may go from 8.5 to 5....my point being that you probably won't have to spend the $2.50 a day when you're running normal chlorine levels. For example, my pool is in Northwestern Louisiana, in full sun from about 8 AM til about 7PM during the summer. Today's air temp topped out at 104, and the heat index with 87% humidity was 109. I started with 8 ppm chlorine this morning, and just tested it a few minutes ago at 4 ppm (CYA 80). A little low, so I added the large size jug of bleach, which in my pool is a 4 ppm increase. Not bad, if you consider that it's been two days since I had to add any--the last time I added was Saturday--put one jug in in the morning because I had a pool full of kids coming over for the day, and then added another jug that evening after they all got out. None since then til tonight.

With my CYA at 80-90 (intentionally), I go through about 4 of the large jugs weekly during the summer. During the winter, after the water temp drops below 60 or so, I only use 1 of the larger jugs every week or so, and I keep my pool open all year--it never closes.

[CarlD]

I think you might have missed the part where Jan said you are fighting something. Until we KNOW your pool is cleared, we may well see further FC drops. If, instead, your FC drop matches Jan's, then you are probably ready to run the maintenance level of 5-10ppm of chlorine.

I don't know why, but this seems to be a season of heavy chlorine usage. I've been adding about half a gallon of 12.5% LC almost every day and am pushing my CYA level up to try to get it to maintain a proper residual level. 1/2 gal of LC is equal to about 1 gal of bleach and costs about $1.70, so I feel your pain. I've had no CC for weeks, my water's clean and my pH is stable, so I'm thinking it's just the heat and sunlight.

Carl

[cooper]

Hey Guys

I was glad to see this thread.... I've been using the BBB method since my new liner I guess it was end of may.

My CYA is aprox 60, PH 7.2 to 7.4, temp 90 and I have to add about 3/4 to 1 gal everyday and sometimes the Clorine level drops to 2.8 or so. Once in a while I miss a day and it drops very low. I didn't think I'd have to add the clorine so often. For the most part the water is crystall clear.

Cooper

[aylad]

I would suggest that you try testing at night after the sun is off the pool and again the next morning before the sun hits the pool. If you lose more than 1 ppm chlorine during that time, then you'll need to shock the pool to get rid of whatever is causing the chlorine demand. With your chlorine dropping that low, it's probable that you have an algae bloom trying to happen.

[cooper]

Thanks! I tested tonight and still low under 2. I'll shock her up on monday and let you know

Cooper

[Watermom]

I wouldn't wait til Monday to shock. You need to do it in the morning if possible or at least tomorrow sometime.