Chlorination: Residential and Commercial Use

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We survived another summer in the pool industry, and this one will be remembered for quite a long time. We have had to deal with COVID-19, and we are now dealing with a shortage of chlorine tablets due to the hurricane & fires as well as a bucket shortage. Wholesale outlets across the nation, especially in the southwest, are essentially out of stock on Trichlor tablets, our mainstay product. Tablets are produced or pressed from Trichlor granular. The outage also affects the sale of Dichlor products.

The residential use of chlorinating tablets can be resolved a little easier than the commercial side on the industry. Tablets in floating devices are common in backyard pools, especially in the summer. They provide slow release chlorine as well as maintain conditioner levels. Often, this can save the homeowner the chore of adding chlorine between service days. Anytime you can avoid your client having to handle any chemicals, do it; less potential for problems such as chlorine splashing up in their face, a young child not knowing the danger inside the chlorine container, dogs, etc. Any chemical is always a potential liability risk. Additional concerns for residential use are to be sure the floater has a locking lid.


Caution: if a floater is allowed to sit on a shallow top step or seat, it will damage the plaster. They just don’t work in every pool. In the short term, you might have to leave the gallon or just increase your weekly chlorination level until this passes.

On the commercial side, it is more of an issue. We rely on a consistent supply of chlorine tablets. Mother Nature has decided to flood the Gulf Coast. The supply chain will come back but for the time being, let us look at chlorination.

Looking back at commercial chlorination, it was initially all just done manually. Chlorination today has many options ranging from tablet erosion feeders, liquid chemical feed pumps, salt cell production, Dichlor granular, and ultraviolet. My opinion is that soon, it will be mandatory that all commercial pools will be required to be upgraded to digital feed with saved memory of chemical levels. This is currently a standard in some states. These systems continually test and adjust chlorine and PH levels. They are a big improvement on safety and stability, but they are not a panacea. They require consistent cleaning of sensors and high/low limit and alarm monitoring. Feed lines will clog and wear over time, affecting system operation.

Chlorination and automation has many benefits essential to commercial operations. You have less reliance of maintenance staff to add test and adjust chemical levels. Most HOA properties have no on-site staff. County health departments require daily testing & recording. The new systems can help with filling that gap. We typically service commercial pools two or three times per week with limited cooperation from on-site staff. Getting site staff to correctly test adjust record and notify you of adjustments of chemicals has almost never been done at an acceptable level. They have many other responsibilities & priorities.

Even with the new digital feed systems, they have limitations. Commercial pools have extreme use at times; parties, urine, bather load, etc. Even the new systems struggle under those conditions. I see salt generation systems with liquid feed for peak demand. This is still not sufficient. The new digital test sensors need routine maintenance cleaning & calibration. Tablet erosion feeders are still valuable as they can fill that peak demand. The same can apply with spa chlorination but not to the same level. Most feed systems can keep up without any tablet erosion feeder, but some heavy use large spas can benefit from tablet use. Tablets do contain conditioner/ stabilizer and the levels must be monitored. pH levels in spas fluctuate quickly. Liquid chlorine has a pH 12.7. Trichlor tablets have a pH of 3. With the desired range often between 7.4 to 7.8, the use of both liquid & tablet keeps the pH range closer to the desired 7.6.

A few things to remember regarding feed chlorination:

1. Follow the manufacturer’s guidelines.

a. For example, never install a liquid chemical feed pump (like Rola-Chem) on the line-side on a circulation system. Do not install a Rola-Chem-type chemical pump and use a receptacle plug for the power supply. It might be easy, but it is dangerous. The circulation pump might fail, the loose prime might not be circulating, etc. You will continue to inject caustic chlorine into the system, creating a hazardous condition for bathers and pool equipment. When the system eventually starts up, there will be an uncontrolled surge of chemicals in the pool.

2. Never mix chemicals, period.

3. Use extreme caution with chemical oxidation regarding indoor equipment. Have a spill containment ability; MDS information posted; bucket, absorbent, dustpan, broom, and basic safety equipment; eyewash; etc. If you have any chemicals stored outside, they must be protected from the general public.

4. Do not leave containers without lids. If your equipment room is indoors, a spray leak can lead to chemical contamination; outdoors, rain can do the same. It can be a hazmat problem.

5. Never install the feeder on the inlet side of heaters; you will destroy the heater.

6. Install as far away from the heater and as close to the return line exiting the equipment room as possible.

7. Install chemical feed return lines after a check valve on the return side. This will eliminate corrosive water or fumes from backing into the heater tube bundle and destroying the metal tubes when the system is off.

8. Tablet feeders that are designed to be offline must be securely attached to the door to prevent accidental damage.

9. If you install a tablet feeder after the pump outlet and before the filter, you will eventually clog the inlet valve and/or the check valve on the chlorinator. The tablets will have been exposed to water, creating a very hazardous condition for you.

10. If you experience this condition, your first indication might be that there is pressure inside the chlorinator as you try to remove the feeder lid. There will be very hazardous yellow-green gas escaping and maybe highly chemicalized water that has been trapped inside the chlorinator from the system (similar to the old gas chamber used on death row). At some point, you are going to be the person to address this situation. These are a few options to resolve the condition:

• Do not breathe the gas!
• Quickly close the chlorinator lid.
• Leave the contaminated area to get fresh air.
• Be sure no one is in the exposed area.
• Let the air clear.
• Plan to address the clog as controlled as you can.

This might require removing the chlorinator to an outside area wearing a safety equipment respirator, safety glasses, and gloves. Remove the lid, and quickly pour the contaminated tablets into a half-full bucket of fresh water with a lid. This will allow you to fix the problem with control.

11. If you When clearing Rola-Chem injectors (they require constant cleaning), there is pressure built up in the line when you remove it. Be careful; pure chlorine will squirt out.

Chlorinators and chlorination are essential components of our industry. They must be dealt with carefully. When correctly stored, chlorine tablets are very stable. It is a good idea to keep a limited backup supply. You never know when Mother Nature and Big Brother might create a supply problem.