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Average Residential vs Commercial Pool Chemical Usage

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Hello everyone!

This is my first forum post here on PGN. Any feedback your have would be greatly appreciated :)

Based on your experience, what would you say the annual average chemical usage is for a residential versus commercial pools? What type of sanitizers and water balancers do you prefer to use?

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There are around 300,000 commercial/public pools in the U.S.  Chlorine use in high bather-load commercial/public pools is primarily from bather load where chlorine oxidizes bather waste.  A rough rule-of-thumb is that every person-hour in a pool uses around 4 grams of chlorine.  A high bather-load pool has one bather in 1000 gallons or less.  If a pool had one bather per 1000 gallons for 12 hours in a day, that would be around 1 ppm FC per hour or 12 ppm FC per day.

Most larger commercial/public pools use chlorinating liquid with peristaltic pumps or use Cal-Hypo while smaller commercial pools often use Trichlor pucks in an in-line chlorinator in the pump room.  Saltwater chlorine generators are also used in some of these pools.

Most commercial pools are lower in bather load (smaller hotel and condo pools).

Chlorine use in outdoor residential pools (around 5 million in-ground and 3.5 million above-ground) is primarily from the loss of chlorine from sunlight.  Bather load is typically very low in such pools so chlorine loss from bather load is usually negligible.  The amount of chlorine loss in sunlight depends on the Free Chlorine (FC) and Cyanuric Acid levels.  Average use in pools not using chlorine as the only algae preventative is roughly 1.5 ppm FC per day.  In pools where chlorine alone is used to prevent algae regardless of algae nutrient (phosphate and nitrate) level, the loss is roughly 2-3 ppm FC per day.  Using the 1.5 ppm FC per day average along with the average in-ground pool size of 19,000 with an average 7 month season and an above-ground pool size of 10,000 with an average 4.5 month season, this translates into 54.6 pounds of Trichlor for an in-ground pool season and 18.5 pounds of Trichlor for an above-ground pool season.

Most residential pools use Trichlor pucks either in a floating feeder in the pool or in an in-line chlorinator in the pump room.  About 15% of pools use chlorinating liquid or bleach as their primary source of chlorine but this needs to be added every day or two (unless a pool cover is used).  About 15% of pools (most are in-ground pools) use a saltwater chlorine generator (SWG).

There are a small number of public pools and residential pool services that use chlorine gas, but that requires special permits and training.

The above numbers for residential pools do not include the extra "shock" products that are added nor clarifiers, flocculants, algaecides, phosphate removers, enzymes or other specialty products.  Over a quarter of residential pools have either cloudy water or visible algae in the current year, over 50% in the last year or current year, 60% in the last 3 years and only around 15% never have a problem.  Pool stores sell these extra products (at higher margins) to "solve" these problems but most are only stopgap measures since none address the core issue of rising CYA levels due to use of stabilized chlorine (Trichlor or Dichlor).

In response to most pools having problems and not getting them solved except through purchase of stopgap expensive supplements, about half a million pool owners per month during peak swim season (May, June, July) visit the Trouble Free Pool website where they become educated about the chlorine/CYA relationship, the pH/TA relationship, and how to manage their pools inexpensively without problems including use of equivalent grocery store products (e.g. Arm & Hammer Baking Soda instead of Alkalinity Up -- both of which are identical sodium bicarbonate aka sodium hydrogen carbonate).

Does that answer your question?

You answered all my questions Richard, thanks for your input!

Wow, I dont log in enough any more. Heres 3 off the top of my head cost wise.

Hotel - High end with a crew of misfits who thought they knew their pool well, as many operators do. They had the benefit of automation (liquid feed) and Ozone but ........ see above, Automation in the hands of some is worse than not having it. They were spending $1000 a month on chems for a little indoot pool and hot tub. I reasoned with them a few times and when they started to listen it went down to $500. It could have gone lower for sure.

Another Hotel, nice but not super high end. Automation (liquid feed) but no UV or Ozone etc. Large outdoor pool used a lot in summer and I remember the number as being the cost of a pack of cigarettes per day, so back then maybe $7. But they understood things better and were better motivated too.

Much as I hate to admit it, one we did was salt, smaller residential poo and totally built for salt. Automated and used CO2 for pH control. And a great Ozone system. I think I fill their 20lb tank up once or maybe twice a year, sell them a bag of salt and I guess a bag of bicarb. Thats it.

However just about every pool that I get my way with are liquid feed systems and Ozone and they all stay very clean and use very little chems.

Whether it’s a residential pool or a commercial one, the primary responsibility is towards cleanliness and safety. However, the responsibility goes much beyond adding treatment chemicals. Here are some of the things one needs to keep in mind to ensure cleanliness and safety:

Filtration: Without this, no amount of chemical treatment will keep the water clean. A filter will remove all particulate matter (dirt and debris) from the water, making it more clear.

Circulation: Water needs to be moved regularly through the pump and filter system. Commercial pools may have a turnover time of 8 to 9 hours, which means that it takes 8 to 9 hours for all of the water in the pool to move through the pump and filter system.

Chemical treatment: This will remove scale and stain formation and corrosion of surfaces and equipment, among others. High pH, high total alkalinity and/or high calcium levels will make water turn cloudy. Thus, proper levels of these need to be achieved.

Chlorine: This helps in controlling bacteria. It comes in many forms - Sodium Hypochlorite (Liquid) Dichlor (Granular) Trichlor (Tablets) and Calcium Hypochlorite (Granular). If you’re using tablets, the concentration of chlorine is higher and you need to use only 2-3.

Safety signs: Ensure that there are safety signs like “no diving” or “watch your children” wherever appropriate. You can check out a range of pool safety signs here: http://www.clarionsafety.com/Pool-Safety-Signs/

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