What Does Baking Soda Do to My Pool?

We have a lot to do to maintain our swimming pools.  We need to ensure our equipment is in working order.  We need to make sure our filters and salt cells are clean.  We need to net out debris.  We need to brush the pool.  We need to either purchase an automatic pool cleaner or else manually vacuum our pools.  We need to test the water and then balance it accordingly.  This involves using various chemicals.  Depending on what we are trying to adjust, will depend on what chemical we use.  I have had a lot of people ask me if baking soda is the same as soda ash.  It's close, but not identical.  Soda Ash is a hygroscopic powder while baking soda can be slightly more abrasive. Both are available in nature, but can be artificially manufactured as well.

NaHCO3- Sodium Hydrogen Carbonate (Baking Soda)

Na2Co3- Sodium Carbonate (Soda Ash)

pH and Alkalinity  in Swimming Pools

These are two fields that will need to be adjusted often.  When they are high, our water tends to be scale-forming which can lead to calcium build-up on our waterline, in our plumbing and even in our equipment.  Salt cells are especially susceptible to calcium build-up.  We never want to adjust our pH without also checking our alkalinity.  They tend to go up and down together on a “buddy system”, but sometimes, one will drop out of range.  For example, if your alkalinity is low, it can cause an unstable pH.  An unstable pH can “bounce” around being high one minute and in range or low the next.  This is known as pH bounce.  So we actually only get an accurate pH reading when our alkalinity is in range.

We would raise alkalinity by using a product called sodium bicarbonate.  Sodium bicarbonate is often referred to as “Alkalinity Up”.  This product is actually the same chemical composition as baking soda.  Approximately 1.5 pounds per 10,000 gallons will raise our alkalinity by about 10 ppm (parts per million).  Now, you can go hit up Costco and get a jumbo size bag of baking soda, or you can go to your local swimming pool supply store and buy some alkalinity up.  This is if you need to raise your alkalinity.

If you are looking to just raise your pH, you would use sodium carbonate aka Soda Ash.  Now keep in mind this will also raise your alkalinity.  They are on a buddy system, remember.  Approximately 6 oz of soda ash per 10,000 gallons of water will raise the pH by only 0.2 ppm and your total alkalinity by 5 ppm.  The only way to just affect pH is aeration or C02.  It can be a bit of a cat and mouse game.  You may need to use soda ash or alkalinity up first and then use acid to bring the levels back down.  pH and alkalinity dropping out of the buddy system does not happen all the time.

Why Should I Care About pH and Alkalinity?

As we briefly discussed before, high pH and alkalinity can cause calcium build-up.  Low pH and alkalinity can make your water corrosive.  Corrosive water can ruin a vinyl liner.  It can ruin equipment, especially heaters.  It can etch your plaster.  It is uncomfortable to swim in and can cause red and burning eyes.  Keep in mind, our sanitizer is most effective when the pH and alkalinity are balanced.

Test, Test, Test

I cannot stress enough the importance of frequently testing your swimming pool water.  How else are you going to know what to add? NEVER add chemicals without testing first.  Always follow product labels and wear the correct PPE (personal protective equipment) when handling chemicals.  Aside from pH and alkalinity, we need to test our sanitizer level.  Chlorine levels should be between 2-5 ppm, but 1 ppm is enough to kill most bacteria.  We need to check our cyanuric acid.  You want a minimum of 30 ppm in a traditionally chlorinated pool and a maxim of 99 ppm.  In a salt pool, I recommend a starting minimum of 40-50 ppm because you are not getting the weekly addition of CYA from tablets like traditionally chlorinated swimming pools.  We need to try to keep our calcium levels between 200-400 ppm.  Always test the calcium levels in your source water before draining to reduce calcium.  Calcium, cyanuric acid and salt can only be reduced by dilution.  Which means splash out or draining and adding fresh water.  You can also hire a company to perform reverse osmosis on your water.  This method is pricy, but if you are in a region that is in a drought or want to be more green, this may be a good method for you to consider.

Draining a Pool

Swimming pools should be completely drained and refilled about every five years.  Always notify the water company so they don’t fine or change your tier. They can also warn you if you are in a high water table.  We don’t want our pools floating down the street! They give this allowance because they know pool water can become unsafe as it gets too old.  What I mean is the chemicals exhaust themselves trying to find room to dissolve and become less efficient.  Even if your levels are in range, it does not mean the chemicals are functioning at 100%.  Since this change in efficiency cannot be measured, go the safe route and drain your pool.  

Every time we add something to our swimming pools, the chemicals only break down to a certain molecular level.  These are known as dissolved solids.  The measure of these is called total dissolved solids, or, TDS.  When our TDS exceeds 2,500 ppm it is time to drain the pool.  This usually takes about five years.  You need a TDS meter to test this.  They can be pretty pricy, even on Amazon.  Since this isn’t something you need to check weekly or even monthly, it probably makes more sense to just take your water to a local swimming pool supply store to have them test your TDS.  See you poolside!