Weekly Pool Service Prosper
QUESTIONS ANSWERED...

What happens if you swim in a pool with too much chlorine?

Answer...

First, when you look at chlorine in a pool, there’s 2 things to test for, Free Available Chlorine (FAC) and Chloramines (or Combined Available Chlorine (CAC) minus the FAC).

Chloramines are molecules that are formed when FAC reacts with oils, sweat, and urine in the water (not just urine, and depending on your pool, not only urine). Chloramines are what gives off the “chlorine smell” and causes irritation of the eyes and skin.

To get rid of the chloramines, you actually have to add more chlorine to the pool. Alternatively, you could backwash the filter and add more water to the pool to try to remove and dilute the remaining chloramines.[1]

Pool cloudiness is usually due to not enough chlorine. If you smell the “pool smell” and it’s cloudy, chances are there is a high amount of chloramines in the water and it needs more chlorine, the pool probably needs to be shocked.

Other reasons for the cloudiness include: a failing filter, or, more likely, a filter that hasn’t been backwashed recently (you run the pump backwards through the sand filter to a drain to clean out all the gunk the filter trapped).[2]

That said, at extremely high levels, chlorine can cause difficulty breathing and asthma-like symptoms, as well as eye and skin irritation.[3] It can be fatal over the course of 30 minutes when exposed to chlorine gas level of 400 ppm or higher. Keep in mind that’s for GASEOUS chlorine levels. Chlorine levels in solution would have to be much higher to even come close to the same effects. The levels typically found in pool water are 2–4 ppm. When a pool is being “shocked” or had a ton of chlorine added to counter the chloramines it can get as high as 40 ppm, which still wouldn’t have a profound effect unless you were submerged in it for hours at a time.

Bottom line, it’s probably not too much chlorine that’s the issue. It’s really difficult and expensive to get that enough chlorine into a swimming pool to cause damage directly. Chances are there isn’t enough chlorine.

At an outdoor pool, the sun, air, and breeze are able to move these chloramines away to not usually cause issues (unless the operators have failed to properly monitor the FAC). Indoor pools need to have excellent ventilation to prevent these same issues. Request to see the logs of chlorine readings as well as reports of health inspections if you’re concerned.[4]

How much chlorine should we add in swimming pools?

Answer...

Good question.

The chlorine level in an outside pool should be 7.5% of the CYA level.

The CYA level should not exceed 50ppm.

NOW. The CYA level will remain constant, declining a very little due to backwashing and splashing.

Chlorine however is constantly declining as it deals with plant / human contaminants.

An ORP machine will constantly add to the chlorine level as the quantity depleats. This requires an ORP feeder, accurate probes in the pipework and constant circulation.

Chlorine tablets constantly add CYA are slow dissolving so very difficult to know levels, they also contain copper sulphate which stains the grout amoung other cmplications. best not use them.

Chlorine granules dissolve quickly, so easy to work out levels. However they contain lots of CYA (10 parts chlorine: 9 parts CYA) Great for new water when / if you want CYA otherwise best not use them for regular disenfectation or you will end up over stabilised.

Liquid chlorine at 12.5% (which is average) adds 1ppm per 833ml in 100,000 lires. This contains no CYA - good.

Pools on average in summer use approx 2ppm per day.

If you add liquid chlorine AT night (no sun to absorb the chlorine) and run minimal CYA (30ppm) then the chlorine will be efficient at keeping the pool clean. Chlorine level will get used up during the day, so add more (at say 2pm) if it needs it. Or just add more each night.

For the chlorine to work really well, and the pool to look and feel great pay attention to the LSI - saturation index.

Search for Robert Lowry - clean pools and spas, his e. books have all the answers. Read up on his CYA controls your pool stuff really interesting.

Search for LSI calculators - the best one (I.M.O) being Orenda tech.

I run over 70 pools. Most use simple peristaltic pumps to feed in Liquid chlorine and HCL (at night). Then use Ultra Violet secondary filtration (circulating disenfected water - the best results use variable speed pumps which are very power economical and run all day cheaply. This combination works REALLY well. The holiday rented pools typically get 4ppm of chlorine every night.

Good luck.