BBB Chlorination

A BBB guide to supermarket poolcare.
Use store-bought bleach, baking soda
and borax to replace proprietary pool chemicals.
SixFeetUnder

BBB Chlorination

Postby SixFeetUnder » Sun 06 Sep, 2009 21:54

Hi all,

First of all thanks for reading. My pool is currently screwed...okay well not really. Water is clear, no staining ...but algae is forming. I recently (if you check the staining forum) has iron stains/manganese stains due to the oxidation and accidental dropping of small fertilizer bits without phosphate to fall into the pool...as I like to call my 'fucktastrophe.' :thumbup:

Now the pool is without the two iron stains after adding in metal free, and rubbing off with stain free and a sponge :lol:

Now algae is forming...I do not have any test numbers for the pool yet (currently ordered Taylor K-2006C) so that's in order. The water is clear with algae right now as said already.

I just recently purchased regular bleach (6.00%), read a crapload about Hardness, Alkalinity, dissociation constants and all that stuff relating to Chemistry of pool chemicals. And I'm still learning. Frankly I don't understand all these formulas I have from a 'pool equations' excel sheet that is similar to poolcalculator dot com.

Anywho...quick question: When Sodium Hypochlorite is added to water, it tends to raise pH, while raising alkalinity (not carbonate).

Now...Outgassing of CO2 to the air in regards to ppm Cl2 lost tends to continue increasing pH (not dropping it). Too much pH is definitely not good as it can cause corrosion with regards to ppting minerals from the water ---if I'm right this would tend to drastically removing hydrogen from the water, thereby contributing CaCO3 (carbonate + calcium) and then contributing to scaling.

Now when adding chlorine...how does one make sure the highly basic water (FAC) does not scale the pool walls/corode? This is one thing I'm so confused about...and clearly I don't have the hang of all these chemicals, their effects, and all that yet....This is definitely not as easy as I imagined.


chem geek
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BBB Chlorination

Postby chem geek » Mon 07 Sep, 2009 01:55

SixFeetUnder wrote:Now algae is forming...I do not have any test numbers for the pool yet (currently ordered Taylor K-2006C) so that's in order. The water is clear with algae right now as said already.

I just recently purchased regular bleach (6.00%), read a crapload about Hardness, Alkalinity, dissociation constants and all that stuff relating to Chemistry of pool chemicals. And I'm still learning. Frankly I don't understand all these formulas I have from a 'pool equations' excel sheet that is similar to poolcalculator dot com.

Anywho...quick question: When Sodium Hypochlorite is added to water, it tends to raise pH, while raising alkalinity (not carbonate).

Now...Outgassing of CO2 to the air in regards to ppm Cl2 lost tends to continue increasing pH (not dropping it). Too much pH is definitely not good as it can cause corrosion with regards to ppting minerals from the water ---if I'm right this would tend to drastically removing hydrogen from the water, thereby contributing CaCO3 (carbonate + calcium) and then contributing to scaling.

Now when adding chlorine...how does one make sure the highly basic water (FAC) does not scale the pool walls/corode? This is one thing I'm so confused about...and clearly I don't have the hang of all these chemicals, their effects, and all that yet....This is definitely not as easy as I imagined.

To get rid of algae, read Defeating Algae . As for using chlorinating liquid or bleach or other hypochlorite sources of chlorine (including Cal-Hypo and lithium hypochlorite), the pH rise from these sources is temporary since the consumption/usage of chlorine is acidic and the pH will drop back down. That is, IF there isn't carbon dioxide outgassing. So if your TA is high, then use of the hypochlorite sources of chlorine will appear to have the pH rise over time, but it isn't the chlorine itself doing that as much as it is having the TA too high.

TA isn't just a pH buffer, but is also a SOURCE of rising pH itself. Essentially, pool water is intentionally over-carbonated. So you will probably want to lower your TA level to 80 ppm or lower and then adjust other water parameters to make the saturation index near zero.

Too high a pH does not cause corrosion. It causes scaling, if other water parameters are such that the water is saturated with calcium carbonate (i.e. if the saturation index gets too high for any reason, a high pH or TA or CH or combination, then scaling can occur).

If you want to minimize the pH swings but don't want to contribute to carbon dioxide outgassing, then you can use 50 ppm Borates in the pool as described here .
SixFeetUnder

BBB Chlorination

Postby SixFeetUnder » Tue 08 Sep, 2009 18:48

Thank you so much chem geek. Will be reading your post over and over again and also the sources given. :)

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