As a manufacturer of salt chlorine generators, we hear of many situations that are blamed on salt chlorine generators (SCGs). Whenever a pool problem surfaces that a pool service tech cannot resolve, the first assumption is usually that the problem is caused by salt. Let’s cover some issues that are known to be related to salt, and then let’s discuss other situations that can be resolved by testing and adjusting operating parameters.
Known Salt-Related Problems
Corrosion – While not fully due to salt, salt can contribute to corrosion issues. We all know high levels of salt can cause corrosion. Just ask anyone who lives along the coast, or where roads are frequently treated with salt. Regarding SCGs, it’s important to inspect and ensure that your pool is properly bonded (electrically). A pool that is not properly bonded can experience electrolysis. Here are some facts about electrolysis corrosion:
- Electrical charges in the water look for a way to discharge to ground.
- Without a proper bond, the electrical charges attack metals in contact with the water. This can start off as discoloration of metals, but can lead to erosion of the metals used in heat exchangers, handrails, light rings, etc.
- Discoloration can be cleaned with an acid solution, but corrosion is not usually detected until it’s too late. It builds up slowly.
- SCG systems require added salt to the pool. This WILL increase conductivity in the pool. Therefore, electrolysis conditions will be accelerated.
Solutions – Poorly bonded pools will experience damage from electrolysis, regardless of if an SCG is used or not. These two solutions will have the most impact in reducing, if not eliminating, electrolysis:
- Ensure proper bonding of your pool. If you’re not sure if your pool is bonded properly, most Master Electricians can make a determination. In some cases, your local utility company may need to be contacted, as electrical charges can stray through the ground from a neighbor’s house to yours.
- For older pools or pools of questionable bonding, “sacrificial anodes” can be used to discharge stray electrical charges. The sacrificial anodes that are most effective are those that are plumbed in your circulation system, with a large anode connected to an external bonding lug, which attaches to a bond wire, and is securely attached to a grounding rod. The image to the right portrays such a device. www.pooltool.com
Deck Degradation – While not fully due to salt, it can contribute to erosion issues. First and foremost, it’s important to make sure that your pool contractor is using stone or deck materials that are compatible with a salt environment. Most soft and porous stones (slate, soft granite, and flagstone, to name a few) naturally experience erosion and delamination of the stone over time. Salt, like corrosion, will accelerate stone erosion and delamination. These types of stones are not compatible, because they will be exposed to water splashing out the pool.
Here’s why this happens. Water containing salt evaporates, leaving salt behind. The salt, when in a dissolved state, can infiltrate or percolate below the surface. When the water evaporates, the salt returns to its dry state, which then can pop or delaminate the soft stones. Interestingly, pool owners that use liquid chlorine (bleach) will also experience this condition, as bleach also contains a fair amount of salt.
Solutions – SCGs can be used on pools with these types of decks by taking the following preventative maintenance steps:
- Seal your deck periodically. This prevents the salted water from seeping into the deck. Instead, it will puddle on the surface of the stone, leaving the salt residue when the water evaporates.
- Hose off your deck regularly. In some cases, weekly may be necessary. Sealed decks will not need this done as frequently as an unsealed deck. Regions of the country that experience rainy seasons will have the benefit of Mother Nature rinsing and diluting the salt on their decks.
- Select a more durable and compatible stone for your deck.
Low Chlorine Conditions – SCGs release a certain amount of chlorine. The output of SCGs is rated in pounds per day (lbs/day). Manufacturers relate these outputs to pools of an approximate size. That’s why you see systems rated for “up to” 20,000 gallons, 40,000 gallons, etc. SCGs are usually capable of producing the rated output only under ideal conditions (running 24 hrs/day, 100% output, and with very low usage). In reality, most pools are not operating 24 hrs/day, nor are they lightly used. Therefore, professionals recommend to use a cell whose output is 1.5 times the gallon capacity of your pool. A 13,000 gallon pool would, therefore, need a system capable of at least 20,000 gallons. Using a larger cell will allow longer cell life, but should be capable of adjustments to avoid over chlorination.
With the increasing popularity of variable speed pumps, longer pump run times allow the use of a lower rated output system, i.e. 16,000 gallon pool using a 20,000 gallon rated SCG.
Here are some tips on avoiding low chlorine conditions:
- Select the right sized SCG for your pool and operating conditions.
- Based on the output of your system, adjust the output setting to maintain the desired chlorine level. Most SCG systems operate on an output between 0 – 100%. Some will allow 1% incremental adjustments, while some only allow 20% increments. Regardless, test and adjust the output levels until you’re able to maintain proper chlorine levels.
- Ensure your pump run times are long enough to allow your SCG to maintain your desired chlorine levels. Some pool owners reduce pump run times when the cooler months come around. Keep in mind that while chlorine demand is not as great in cooler temperatures. If you’re heating and using your pool during cooler months, the reduced pump run hours will reduce the amount of chlorine that your SCG is capable of generating.
- For OUTDOOR pools, ensure you maintain at least 50 ppm of stabilizer (also called cyanuric acid and conditioner). This protects the chlorine from degradation from the Sun’s UV rays. With low stabilizer levels, chlorine is quickly consumed, which will require higher output settings on your SCG, and accelerated cell wear. For commercial pools, follow your state guidelines for maximum stabilizer levels.
For unknown low chlorine conditions, a few quick tests can be performed to determine if your SCG is working properly:
- Remove and inspect cell for calcium scale build up on the blades. Ensure proper salt level in the pool and ensure proper flow through the cell.
- Put your SCG on 100% (or Boost for systems equipped with this feature). Allow the system to run for at least one minute (this allows the cell to ramp up to full output), then run the diagnostic (TEST) mode of the SCG. Compare the results with the manufacturers’ normal operating parameter. Usually, if the cell amperage and voltage are within normal operating parameters, you are making chlorine.
- While the cell is activated, loosen the union after the cell and take a water sample. In most cases, testing the chlorine level from this water sample will show a higher chlorine level than what’s in the pool.
- If steps 1 – 3 are correct, you may have a high chlorine demand condition in the pool. Follow these steps to determine if these conditions exist.
Overnight Chlorine Loss – After the sun goes down, manually add enough chlorine to elevate your chlorine level to 4 ppm. Let it circulate for at least 30 minutes and then shut the pump off. Retest the chlorine level to determine your chlorine level. In the morning, retest the chlorine level and determine how much chlorine was lost overnight. Keep in mind that with the pump off, with no one using the pool, and with no sunlight, there should be very little chlorine loss—no more than 0.5 ppm. Excessive chlorine loss points to an unusually high chlorine condition that normal chlorine generation may not overcome.
Solutions— Take the following steps to correct for chlorine loss:
- Super Chlorinate – Shock your pool. Depending on your region and water conditions, the type of chlorine or non-chlorine shock used can impact your water chemistry. For areas of high calcium hardness levels in the water, do not use Calcium Hypochlorite. For indoor pools or pools that are high in stabilizer levels, do not use granular tri-chlor (sometimes labeled Black Algae treatment) or tri-chlor tablets. These forms of chlorine will only increase already high levels of calcium or stabilizer. Super chlorination will usually help to overcome high chlorine demand conditions by trying to satisfy the high demand. Sometimes the use of a non-chlorine shock treatment, Potassium MonoPersulfate, can more effectively oxidize contaminants in the pool.
- Test for other high chlorine demand conditions such as phosphates, nitrates, combined chlorine (chloramines), and Total Dissolved Solids (TDS). If these are higher than acceptable, treat accordingly, either with specific chemicals to lower these levels, or partial dilution by water exchanges.
- Avoid the use of any Sodium Bromide based products. These are usually the main ingredients in chemicals used for Yellow or Mustard Algae treatments. Read the container for the list of ingredients. If it contains Sodium Bromide, discontinue using it
- Turn the SCG OFF. Manually add chlorine to maintain 5 ppm for up to 2 weeks. When you no longer need to add chlorine to maintain 5 ppm, you can resume normal SCG operation.
High Chlorine Conditions – SCGs require the pool owner to adjust the output to maintain the desired chlorine level. These are not “Set it and forget it” devices. You should avoid the mindset that if a 40% output is good, then 100% is better. You can get into a high chlorine condition. High chlorine conditions can cause eye and skin irritation, bleached bathing suits, and corrosion of metallic components in contact with the water.
SCGs can generate 0.5 lbs/day up to 2 lbs/day for a residential system. 2 lbs/day output is the equivalent of 2 gallons of pool store (12%) bleach, or 3.2 lbs of Calcium Hypochlorite. Running at 100% is like adding 2 gallons a day!
Pools that experience big bather load swings throughout the day are best maintained with a Chemical Automation system. These are also known as ORP/pH controllers, which uses sensors to test for pH and Chlorine levels, and automatically adjusts these levels with a pH chemical pump and the SCG cell.
Examples of pools with bather load swings are pools with automatic covers, competition pools, swim schools, municipal pools, spas, etc. When not in use, there is little chlorine demand. However, when bather loads increase, higher than normal chlorine dosage is needed.
Salt Build-up on the Tile – Salt, when wet, will dissolve into a solution form. When there is a white residue build up on the tile line, waterfall, or spa spill over, can it be salt? A simple test is to wet it. Salt will dissolve back into a solution. If it remains, most likely it is calcium, a result of high calcium hardness conditions. Calcium can be dissolved by the use of an acid solution, then testing and adjusting your water chemistry to ensure balanced water conditions (according to the Saturation Index). Excessively high calcium hardness levels will need to be diluted by partial water exchanges.
So, can your pool woes be caused by salt? Sometimes. However, salt is often mistakenly blamed, when other issues are actually responsible.
The conditions covered in this blog are the most common pool conditions that are blamed on salt chlorinators. While the SCG can contribute to some of these, most of these issue can be prevented by taking the steps we suggested. Salt systems have been used in pools since the 1960’s, and have proven to be a safe and reliable means of pool water treatment. In fact, the majority of pool owners who have switched from traditional chlorine treatment systems to SCGs say they will never go back.
Keep on top of proper operating conditions and maintenance for trouble-free SCG operation. Should you have questions about your salt system, feel free to contact me directly. Sean@teamhorner.com