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Saltwater Pool Chemistry

What is the water chemistry like with a salt pool?

The ideal water chemistry levels that you’re trying to maintain in your swimming pool actually don’t change (with the exception of your salinity level). You check for the same things in a saltwater pool, using the same testing methods that you used to (again, plus checking for salinity). Of course, the BIG difference with a salt pool is that it puts an end to your #1 water chemistry headache, your chlorine level. You’ll see that Free Chlorine level is consistently in range, without you having to buy, store, add, and micromanage that level.

 

Ideal Swimming Pool Water Chemistry Levels

Pools Spas
Free Available Chlorine 1.0 - 3.0 ppm 3.0 - 5.0 ppm
Salinity 3500 - 4000 ppm 3500 - 4000 ppm
pH 7.2 - 7.8 7.2 - 7.8
Total Alkalinity 80 - 120 ppm 80 - 120 ppm
Calcium Hardness 200 - 400 ppm 150 - 450 ppm
Stabilizer (Cyanuric Acid) 60 - 80 ppm 60 - 80 ppm
Saturation Index -0.2 to +0.2 (0 Best)   -0.2 to +0.2
Phosphates & Nitrates None (0 Best) None
Effective TDS (TDS minus salt)   Low Low

 

One misconception when switching your pool to a Salt Chlorine Generator is that water chemistry is no longer important, and that you never have to do anything again. Salt systems work so well and have gained such a reputation for slashing the maintenance required on a pool, that from what people hear they may think that the system is meant to do it all! You'll hear it when you talk to people with a salt pool that they will tell you how little they have to do anymore. When they tell you that they haven’t had to touch their pool, that is certainly in the realm of possibility but that isn’t a given, and its important to be clear that a Saltwater Chlorinator isn’t doing anything to manage those other supplementary water chemistry levels – pH, Alkalinity, Stabilizer, etc… Those levels may not change frequently, buy they DO still need to be kept in range.

So, it’s important to regularly check water chemistry and maintain it as stated in manual. Regularly doesn’t mean every day. Start by testing every week, keep track of how things change, and you may see that based on your pool’s behavior you may be able to check even less frequently. In addition, you know you need to check your water chemistry when you notice if something out of the ordinary occurs with the pool, such as suddenly having cloudy water or having to clean your salt chlorinator’s cell more frequently than normal. Its always a good idea to check after a rain storm or heavy pool use.

When it comes to water chemistry, there are many different levels that make up ideal balanced water chemistry, such as Free Chlorine, Combined Chlorine, Total Chlorine, salinity, pH, Cyanuric Acid, Total Alkalinity, Calcium Hardness, Phosphates, and Nitrates, even things like metals and ammonia. Each component in water chemistry is important and often has an impact on other chemistry levels (not to mention the pool and your swimmers). For example, when your Cyanuric Acid is out of range, you may quickly see your Free Chlorine depleted. However, just to reiterate, this relationship of chemical balances does not change just because you have a salt pool. Your salt system is a chlorine generator that creates free chlorine, which of course does tend to be most of what people fight with on their pool.

The best way to check your water chemistry is to take a sample of pool water to a local pool store and do a full around diagnostic test. TIP: ask the pool store to confirm that they test each of these important chemical levels, and also provide the pool store with a copy of your salt system’s manual so that they know what salinity range your system works with.

Once tested, compare your water chemistry results to the levels in your salt system manual, and follow your pool professional’s instructions to adjust these ranges into ideal levels as needed.

PRO TIP: After check your chemistry levels, calculate your LSI. The LSI is Langelier Saturation Index, which determines how scale-forming or corrosive your water is – very important! To check your LSI, all you need is to put water chemistry levels on an online LSI calculator and it does the calculation for you. A popular website is aquacheck.com Your optimal LSI level is 0, and certainly should be between -0.2 and +0.2

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