Shock Over Chlorine For Indoor Pool

[pred8er]

Hello All,

I am a owner of an indoor pool which came with the house i just purchased. I have not owned a pool before however I am slowly getting into reading about maintaining the pool myself instead of just having someone else do it for me.

A friend of mine suggested that I simply drop in 1 bag of shock weekly in order to keep it clean and running smoothly.

He also has an indoor pool and this is all he does.

Would doing this on a weekly basis be enough to keep everything OK? Or should I also be using chlorine tablets?

I have a heater that warms the water (common?) and I have read somewhere that using a chlorine dispenser can damage the heater elements - is this true?

Thanks all.

fyi the pool is 20,000 gallons. The pool is fairly long but the deepest area is around 6.5 - 7ft deep only.

[chem geek]

Because an indoor pool is not exposed to the UV in sunlight, the chlorine tends to last longer. On the other hand, without the UV from sunlight, there can be more of a buildup of some chloramines and organics. So some people get a UV system for supplemental oxidation in the circulation system.

As for chemical dosing, though the quantities are less, the procedure is the same as with an outdoor pool. You want to maintain a chlorine level in the pool and that starts by having an accurate drop-based test kit such as the Taylor K-2006 you can get from http://www.amatoind.com/taylor-test-2006-p-555.html'>Amato Industries or from http://tftestkits.net/Taylor-K-2006-p27.html'>TFTestkits.net.

You might be able to get away with adding chlorine only once a week, but if the pool is kept warm (88-90ºF) like a therapy pool, then the chlorine usage may be somewhat higher and you'll need to add chlorine twice a week. You'll just have to measure it and see how quickly it drops each day.

To moderate chlorine's strength, you would use a small amount of Cyanuric Acid (CYA) in the water, say 20-30 ppm, and you would not use any stabilized chlorine (such as the Trichlor tabs/pucks you are referring to) once the CYA level was established. Stabilized chlorine will increase the CYA level. You would use a hypochlorite source of chlorine instead, most likely bleach or chlorinating liquid. You could use Cal-Hypo but would need to monitor the Calcium Hardness (CH) which would increase from use of that product. The following are chemical facts independent of concentration of product or of pool size:

For every 10 ppm Free Chlorine (FC) added by Trichlor, it also increases Cyanuric Acid (CYA) by 6 ppm.

For every 10 ppm FC added by Dichlor, it also increases CYA by 9 ppm.

For every 10 ppm FC added by Cal-Hypo, it also increases Calcium Hardness (CH) by at least 7 ppm.