Minimum Pool Maintenance This Year! Why?

[Allen G Myerson]

In fact, baking soda does cost less than sodium carbonate, so there would not be much cost savings anyway.

You can buy baking soda for about 60 cents per pound, whereas sodium carbonate will cost closer to $1.00 per pound.

Also, depending on the pH, there will be some pH rise directly as some of the baking soda takes up hydrogen ions to become carbon dioxide and water. At a starting pH of 7.0, about 18.3 % will become carbon dioxide and water.

[Allen G Myerson]

It takes roughly 1.6 times as much baking soda to neutralize the same amount of acid as 1 pound of sodium carbonate and sodium carbonate costs about 1.6 times as much as baking soda. Therefore, from a cost basis, you are at about break even.

[mx357xm2]

Trichlor tabs contain 90% availabale chlorine, leaving only 10% for CYA and other additives. This being said, if the pool used the 2.4 ppm per day chlorine as you claim, then 10% of that would be 0.24 ppm CYA. leaving you with 160 days before a 40 ppm increase would have taken place, well within the spring/summer I claimed. Also, that does not account for the water loss/replacement which will lower the CYA levels even further!!! Also, that is if CYA took account for 100% of that 10% trichlor not taken up by chlorine.

Joey, please check the lids on the chemical containers in your store. Based on some of your posts, I am concerned that you might be being exposed to excessive levels of chlorine and other chemical fumes.

[chem geek]

2C3Cl3N3O3 + 6H2O <> 5H+ + 3OCl- + 3HOCl + 2C3H2N3O3

If you were trying to show half of the chlorine being hypochlorous acid and half being hypochlorite and most of the CYA being cyanurate ion, then the equation would be:

2C3Cl3N3O3 + 6H2O ---> 5H+ + 3OCl- + 3HOCl + 2C3H2N3O3-

where you left out a negative charge on the cyanurate ion. In practice, of course, most of the chlorine is attached to CYA as chlorinated isocyanurates since the water already has extra CYA in it -- that is, most of the HOCl and OCl- results in C3HClN3O3- and similar compounds (see this scientific paper for a full technical description of the equilibria involved).

As for the baking soda vs. pH Up, I only used Trichlor during my first year and a half of pool ownership around 7 years ago, but I used pH Up for pH control and though initial addition clouds the water, it cleared up soon after circulationg/mixing. Perhaps if the water is over-saturated with calcium carbonate (i.e. has a positive saturation index) that would be more of a problem, but when the water is balanced it shouldn't remain cloudy. The point about metal staining or precipitation from locally high pH is well taken.

As for pricing, if one is looking at the Alkalinity Up equivalent in stores of Arm & Hammer Baking Soda, then one needs to compare the pH Up equivalent which is Arm & Hammer Super Washing Soda (careful: not the laundry detergent).

As for the pH rising from baking soda addition, this is tricky to manage properly since the way you add the baking soda makes a difference as to how concentrated it gets locally causing bubbling that outgasses some carbon dioxide as you are adding it. I suppose with practice one can learn a technique that is consistent and keep a higher TA to keep things in balance, though that may be hard to achieve in places with hard water where a higher CH combined with that higher TA makes maintaining a decent saturation index more difficult (unless one maintains a lower pH, but one doesn't want to get too low). Also, for those who use pool covers, the outgassing of carbon dioxide will be limited so more direct sources of raising the pH would be needed (when using Trichlor, etc.). 20 Mule Team Borax is an option for raising pH that raises the TA about half as much bringing it close to where it started when the pH is restored. Of course, that eventually increases borate levels.

[James Watson]

chem geek,
What is your opinion about using sodium hydroxide to raise pH, if one can find it at a good price? Is there any reason, other than safety, that you know of why it isn't sold for use as a pH increaser?

It doesn't seem like it would be any more dangerous than many other pool chemicals such as muriatic acid.

[chem geek]

That's a good question for which I don't have a good answer. Sodium hydroxide (aka lye or caustic soda) is a pure base and a compliment to Muriatic Acid. It shouldn't be any more dangerous and in fact is mostly what crystal Drano is composed of (though that product is not pure enough nor granular enough to be used in pools). Sodium hydroxide would work best in pools that use Trichlor, but don't get a lot of carbon dioxide outgassing, such as those with pool covers that are on most of the time.

[ItsAllInTheNumbers]

Trichlor tabs contain 90% availabale chlorine, leaving only 10% for CYA and other additives.

Ummm not quite. Let's look at the chemical structure of trichlor, it's basically a cya ring with 3 chlorine molecules attached to it.

Let's find the molecular weight of trichlor (it's 235 g/mol), the chlorine molecules (it's 106 g/mol) and the cya alone (it's 129 g/mol).

106 ÷ 235 is 45%
therefore 45% of trichlor by weight is chlorine. You have to multiply that figure by 2 (for reasons I won't get into here), so trichlor yields 90% available chlorine (when compared to chlorine gas).

129 ÷ 235 is 55%
therefore 55% of trichlor by weight is cya.

[Allen G Myerson]

232.41 grams of trichlor contains 212.718 grams of Cl2 equivalent, but only 106.359 actual grams of chlorine. The chlorine only makes up about 45.76 % of the trichlor. About 54 % of the trichlor is cyanuric acid.

[joansy1]

I have used a product called Pool Line-Away and it quickly removes the calcium line from the tiles. Just put the wheel in a portable drill and off the calcium goes. :