Using Baking Soda in a Hot Tub

Why Use Baking Soda in a Hot Tub?

I’ve noticed several searches recently on this subject so i thought i might expound on it a bit.  Baking soda, (chemical name: sodium bicarbonate) can be an  important additive for many hot tubs.   The primary reason for using "bicarb"  is to raise the total alkalinity of the water. This Buffers your Ph against change, raises it slightly and keeps your water from being aggressive to your equipment.  As you probably already know.. perfect Ph for a hot tub is between 7.2 and 7.8.  With the ph scale from 0 to 14,  with 0 to 6  being  acidic and 8 to 14 being  basic,  the "7′s" are  considered "neutral."   That being said.. the Ph scale is exponential…like the richter scale. A pH of 6 is 10 times more acidic than a pH of 7.  It all has to do with hydrogen ions but i’m not going to get into that now. 

Aggressive (acidic) water is the single most damaging issue that confronts hot tub owners.  Aggessive water will EAT your heater element up .. fast!  Even if the damage is slight… a little pinhole in the sheathing that protects a heater element’s electric core, the heater (or element)  is now garbage, will cause GFCI tripping, and must be replaced!  

So how, you ask, did my water become aggressive?   Because certain products you may use in your hot tub affect the pH and alkalinity.  Probably the biggest culprit is one of the most popular sanitizers in the industry :  Bromine.  Those convenient little tablets have a pH of around 2.  You throw your floating bromine  feeder in water that is perfectly balanced:  pH between 7.2 and 7.8  with an alkalinity of 80 to 140 and guess what happens.  The Acidic properties of the Bromine bring DOWN your pH AND alkalinity!  Now, i realize that you have a cover on your hot tub, but when you remove it., where is your bromine feeder?  Its sucked up against the skimmer or caught in your filter wier.  The water flowing across it and drawing it to these suction ports of your hot tub is now pulling LOW pH water through your pump and pumping it right across your filter element!  Can you say "formula for disaster?"  At least to your heater element!

there are other products that can erode your pH and total alkalinity as well.  Tabletized chlorines like trichlor also have extremely low pH.  Anytime you CAN check the pH of a product do so! 

How do you prevent this erosion of pH and Alkalinity?  BAKING SODA!  Good ole Arm and Hammer! Sodium Bicarbonate…YES!  Since Bicarb raises you total alkalinity, it also will bring up your pH and protect it from eroding. 

I often get calls and letters from people saying that their pH is high and they cant get it to come down.  My question is usually: what is your total alkalinity?  Many times the answer is "I dont know"  My next question is how are you testing your water?  Most people who are testing their water with drops can experience a phenomenon that bromine can cause: a "seemingly high" pH.   The problem with many of the 2 in 1 test kits is that they don’t test alkalinity!  My reccommendation is to use 4 in 1 test strips.  These strips will give you a total Alkalinity reading which is very helpful when trying to decide if you water is aggressive.  My experience with bromine is this… you will NEVER have a high pH and you will always be adding bicarb to bring UP the pH and TA of the water.   If you use bromine and aren’t adding bicarb on a regular basis, i can promise that your water is aggressive. 

Of course now you want to know how much to add.  It all depends on where your alkalinity is when you start, but if you add it in 1 to 2 ounce increments and closely monitor daily you should be able to come to your own formula based on your experience. NOTE.. if your ph and alklyinity are radically low.. don’t be shy about using a  third of a cup or so IF you can’t drain.  If you CAN drain and refill or drain half and dilute.. that would be a good start.. Then if still low, you can add some from there.

Fresh fill water can solve many problems and one of the reasons i reccomend that over a heavy dose of bicarb is that if damage has been done.. IE you water now has dissolved metals in it, radically raising the pH can cause these metals and minerals to immediately come out fo solution and turn your water shockingly orange or blue.  This indicates metals in the water and these metals are there because the acidity of the water has dissolved them. 

Fill water testing is always reccommended.  For those of you who have read the Spa Care Guide, you know i recommend testing Fill from the start to know from the beginning what your values are,  A point to know is that  municipal water supplies need to keep their water in the good and neutral range as well or else copper pipes, iron pipes and concrete pipes will be damaged by low pH.  Well water is different and may vary extremely across the board. For more info Check the Spa Care Guide..



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