Salt Water Chlorine Generators (SWCG)
Basic SWCG Recommendations
The following is a good recommendation for SWCG’s:
The following water balance tips for SWCG’s will help you maintain your pool with the fewest problems. Following them closely will mean that you will probably never need to shock your pool, and you will maintain a more stable pH than if you go outside of these suggested limits. They may or may not agree exactly with what the manufacturer’s recommend, but they do work and will help you maintain your salt pool easier.
The first step is to adjust the salt level to the manufacturer’s recommended range, which is usually between 2,800 and 3,200 ppm. Add the salt slowly (maybe 2 bags in the morning, another 2 at lunch and 2 more in the evening). Once you think you are getting close, check the levels with strips or a meter (do not trust the salt cell, as they are not always real accurate!). Remember that you can always add more salt, but it is difficult to remove too much!
Next, adjust the CYA (Cyanuric Acid, conditioner, stabilizer) to between 60 and 80. One of the biggest mistakes that many SWCG owners make is not having enough CYA in the water. As with salt, add the CYA slowly (It can take up to a week for the CYA to assimilate into the water, and, like salt, too much is a task to remove. In the case of CYA, too much will also impede the ability of chlorine to do its job.) This can create a lot of problems with the water, like higher acid demand, algae, cloudy water, or even early cell failure.
Set your pump to run a minimum of 8 hours a day initially, and adjust the output of the SWCG so that your free chlorine level stays between 3-5 ppm. Running the pump shorter than 8 hours can keep your pool sanitized, although it will require a higher chlorine generation level, which will shorten the cell life. Make sure that if you are using a 2 speed or multi-speed pump that you have it set high enough to activate the SWCG’s flow switch.
You will want to adjust your TA (Total Alkalinity) to between 60-90 ppm. This is very important, as this is beneficial in buffering the pH.
You will next need to adjust your pH to 7.5-7.6, but not any lower. Monitor your pH and when it climbs to 7.8 add acid to lower it back to 7.5-7.6. It is very important that you maintain these parameters to avoid scaling.
Calcium Hardness (CH) needs to be between 200-400 ppm for plaster pools, and 250 ppm for fiberglass pools. Vinyl pools are alright if the CH is at 50 ppm, or higher (check your equipment manufacturers specifications for calcium levels as well. Too low of calcium in the water will void some manufacturers warranties.). You should not be much above 400 ppm, or you will have to keep a close watch on your pH to prevent scale build up in the cell. You may find that sometimes your fill water will have high calcium levels, and your numbers are higher than recommended. This is prevalent in states in the south mostly. It is not really that big of an issue as long as you maintain your pH as recommended above, although CH of greater than 400 ppm is not ideal. pH rise is probably the most common part of your waters chemistry that will predict scaling condition. High pH leads to scaling; always! it is imperative to keep your pH below 8.0 to prevent scaling.
You might also consider adding borates to the pool, in a 30-50 ppm concentration. This will help pH stability with a SWCG; particularly when the TA is kept in the 60-90 ppm range, and pH is kept between 7.5-7.8. However, it can be useful even if you go out of this range, to some degree. 20 Mule Team Borax is the most common borate product, although there are others, and this can be purchased at most grocery stores. It is typically found in the laundry aisle. It is important to understand how to add borates, so please post if you do not know and we will get you started.
FC wants to be between 3-5 ppm, based on an eight (8) hour run time, or longer.
pH needs to be maintained between 7.5-7.8
TA must be in the 60-90 ppm range.
Calcium Hardness (CH) should be:
50 ppm (minimum) for vinyl
250 ppm for fiberglass
200-400 ppm for plaster
CYA between 60-80, although some manufacturers suggest up to 100 ppm (usually requires higher FC at this level).
Salt between 2,800-3,200 (remember, you can always add more, but it is difficult to remove excess).
Borates are optional, and should be between 30-50 ppm, if used.
SWCG Water Balance Recommendations
These water balance tips for SWCGs will allow you to maintain your salt pool with the fewest problems. Following them means you will probably never need to shock your pool, and you will be able to maintain a more stable pH than if you go outside of these limits. They may not agree exactly with the manufacturer’s recommended levels, but they do work and will help you have a SWCG that does what you purchased it for!
The first step is to adjust the salt to the manufacturer’s recommended range (usually around 2,800-3,200 ppm, although some models do need a higher level.) Start out by adding gradually and checking your levels. You can always add more as needed, although being slightly higher is not a real big deal, since the salt level will tend to fall over time.
Secondly, adjust CYA to between 60 and 80. The biggest mistake that many SWCG owners make is not having enough CYA in the water. This can create problems like high acid demand, algae outbreaks, cloudy water, or early cell failure. Remember to add less CYA than you think and check it a week later. CYA, Like CH, can be expensive to remove (water draining and replacement, or R/O treatment, where available) if you put in too much. Again, it is always easy to add more, but somewhat challenging if you have too much.
Run your pump 6-8 hours a day, and adjust your cell output so your FC stays between 3-5 ppm. Even if you can produce enough chlorine with a short pump run time, you will need to set your system to a higher cell output to achieve this. You will have fewer problems if you run the pump 6-8 hours during the day, and at a lower output percentage. This will help to protect your cell and extend it’s life, saving you replacement costs sooner than later.
Next, adjust your Total Alkalinity to 60-90 ppm. This will help with your pH.
Adjust your pH to 7.5-7.6, and do not let it get any lower. Monitor your pH, and when it climbs to 7.8 , add muriatic acid to lower it back down to the 7.5-7.6 range. This is very important when using a SWCG.
Keep your Calcium Hardness around 300 ppm for plaster (between 200-400 will work fine, however) and around 250 ppm for fiberglass pools. Vinyl pools are alright if the CH is at 50 ppm or higher (but make sure to check suggested levels for your equipment. Many manufacturers have specific CH requirements and will void warranties if not maintained). In any case, CH should not be much above 400 ppm or you are going to have to keep close watch on your pH to prevent scale buildup. Remember that sometimes your fill water will have high calcium levels, and your numbers will be higher than recommended. To a degree, this can be somewhat controlled if you maintain your pH as recommended above. pH rise is the one factor that will predict scaling condition, as high pH leads to scaling. Keep pH below 8.0, and make every attempt to keep the CH below 400, if possible.
Finally, as an option, adding borates to your water, in a concentration of 30-50 ppm, will help with pH stability with a SWCG. This is particularly true when the TA is kept in the 60-90 ppm range and pH is kept between 7.5-7.8, although it can be useful even if you go out of this range somewhat. There are several borate products on the market (Supreme Plus, Optimizer, Maximizer, Endure, and 20 Mule Team Borax). You can buy the last one at the grocery store, and it is found in the laundry aisle. If you don’t know how to use borates, we will explain that in another area.
FC 3-5 ppm (6-8 hour pump run time or more, depending on the cell output level chosen)
50 for vinyl (always check manufacturers equipment levels first before allowing to be this low)
250 for fiberglass
300 for plaster (although in the range of 200-400 ppm is fine)
CYA 60-80 (some manufacturer’s recommend up to 100 ppm,but we do not suggest going this high)
Salt Add slowly and adjust, although 200-400 ppm above recommended optimum level will be fine as the level will fall with splash out
Borates 30-50 ppm (again, use of borates is entirely optional)