Should I have to keep adding sodium bicarb?

Problems relating to pH and total alkalinity.
Increase ph, increase TA. Reduce pH, reduce TA.
pH chemistry advice and techniques for the pool.
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Should I have to keep adding sodium bicarb?

Postby minuteman » Fri 04 Nov, 2011 08:56

If my pool is properly balanced between Cl and pH (automated system, I think it's slightly out of calibration) should I have to keep adding sodium bicarb to keep the alkalinity levels up? They fade over time but stabilize below our minimum level (90ppm-120ppm).

I will be calibrating it next week and see what happens so I'll find out either way, but I figure why not ask an experienced forum!

Also I think the additive is sodium bicarb (please correct me on this, it doesn't say what it is made of) they just give me this product called total alkalinity, it works.

Trying to go through less total alk and acid, obviously when I add the alk it uses up acid, if that's just the fact of things then that's cool too, I'm not paying for it - haha.

chem geek
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Should I have to keep adding sodium bicarb?

Postby chem geek » Fri 04 Nov, 2011 22:29

The Alkalinity Up product from the pool store is sodium bicarbonate and is identical to Arm & Hammer Baking Soda you can get in a grocery store. See this post for more info on grocery store equivalents to pool store products.

Your TA would drop if you are adding acid to the pool either by adding actual acid (e.g. Muriatic Acid or dry acid) or by using a net acidic source of chlorine such as Trichlor or Dichlor. If you use a hypochlorite source of chlorine (e.g. chlorinating liquid or bleach or Cal-Hypo or lithium hypochlorite) then you will not be lowering your TA.

If you are using a hypochlorite source of chlorine, then you may be going through the yo-yo of acid addition to lower pH that has risen, the TA then gets lower, add sodium bicarbonate to raise TA, then pH rises again so add more acid, etc. Stop trying to keep the TA as high as you are doing. Let it drop lower. That should lower the rate of carbon dioxide outgassing which is the primary source of pH rise in most pools. Pools are intentionally over-carbonated and TA is a measure of that. If you do find greater pH stability at a lower TA level, then you may need to raise the Calcium Hardness (CH) or target a somewhat higher pH (such as 7.7) to keep the saturation index near 0 if you have a plaster pool. You can use The Pool Calculator to calculate the saturation index (and dosages for chemicals).

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