How much chlorine to add.

Chlorinating, maintaining the right chlorine levels,
chlorine problems. Dichlor, trichlor, cal hypo, bleach,
granules, chlorine pucks and chlorine sticks.
Crimson
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Posts: 10
Joined: Thu 21 May, 2009 12:07
Location: Seminole, FL

How much chlorine to add.

Postby Crimson » Thu 21 May, 2009 12:17

Hello everyone,

New pool owner here.. purchased a short sale house that had a pool that sat for 1.5 years. Drained, had the pool resurfaced (marcite) and refilled. Thanks to these forums I have been been successful in getting my pool to near 'perfect' condition. Here are my stats:

FAC - 4.0
TAC - 4.0
pH - 7.4
TA - 100
Calcium Hardness - 220
CYA - 40
TDS - 500

So I'd like to maintain those #'s. I have a puck system that generates chlorine, but I would like to set that real low and use liquid chlorine to keep the CYA numbers from getting too high. How much liquid chlorine should I be adding and how often? My pool is approximately 15000 gals but I don't have the exact #, so I need to error on the LOW side for now. Puck system has been maintaining the 4.0 level for the past week.. I plan on turning it down further and only having at most 2 pucks in the system.

So, whats a good rule of thumb here on how much chlorine to add? Like I said I'd like to turn down the puck system, and begin adding liquid chlorine on a recommended interval and testing it daily until I find out exactly how much I need to use. But would appreciate some advice on where to start.

For what its worth I am in the Tampa, FL area.. pool gets a lot of direct sun.


chem geek
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Joined: Thu 21 Jun, 2007 21:27
Location: San Rafael, California

How much chlorine to add.

Postby chem geek » Thu 21 May, 2009 14:22

With a lot of direct sun and a CYA level of 40 ppm, you'll probably lose around half of the FC each day. So if you only used chlorinating liquid or bleach you'd have to add it every day going to 6 ppm FC and ending up with 3 ppm FC.

You could raise the CYA level to 80 ppm and lose less chlorine in spite of maintaining a higher FC level. You'd drop perhaps 15% of the FC level in a day, but would need to have a minimum of 6 ppm FC so would add chlorine to get to 8 ppm and then would lose 1-2 ppm FC per day. However, if you let the chlorine get too low and algae starts, then the higher CYA level makes it harder to shock the pool since it requires a higher FC level (around 30 ppm).

You can use (at extra cost) a weekly algaecide or a phosphate remover if you wanted supplemental algae prevention and not worry about the chlorine getting too low. It's not necessary, but an option if you feel you won't be able to maintain the chlorine level. Another option is to add 50 ppm Borates to the pool which are not only a pH buffer, but a mild algaecide.

With a mix of chlorine sources, you'll probably be OK. As for how much you will need to add, figure on 2 ppm FC per day though you may get down to 1 ppm FC per day and look up the amount on The Pool Calculator .
Crimson
Pool Enthusiast
Pool Enthusiast
Posts: 10
Joined: Thu 21 May, 2009 12:07
Location: Seminole, FL

How much chlorine to add.

Postby Crimson » Thu 21 May, 2009 15:09

Thanks for the advise. Its been raining and cloudy for the past week here in FL.. how much does that impact the chlorine loss?
chem geek
Pool Industry Leader
Pool Industry Leader
Posts: 2382
Joined: Thu 21 Jun, 2007 21:27
Location: San Rafael, California

How much chlorine to add.

Postby chem geek » Thu 21 May, 2009 21:24

The cloudiness usually lowers the chlorine loss, though some UV gets through clouds anyway (just not as much). The rain usually has little impact unless the rain is "dirty" with contaminants (dust, pollen, etc.). If your TA is high, then the aeration of the water from the rain drops can have the pH rise.

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