Poolbee,
Your Alk is fine and yes, it will move up and down with pH.
Could you have mistaken Ch for Alk on the other forum? Regardless, 80-120 is a generally accepted range for Alk.
I just read on another forum that TA for vinyl pools is 125-150. I had never heard that before and my pool builder, who only builds vinyls and has been for over 25 years, suggests the standard 80-120. Mine has been holding steady at 110. Should I be adding some baking soda or just leave it alone.
All of my numbers have been perfect, except the pH for which I just added Muriatic acid. Can or will adding acid change the TA?
Poolbee,
Your Alk is fine and yes, it will move up and down with pH.
Could you have mistaken Ch for Alk on the other forum? Regardless, 80-120 is a generally accepted range for Alk.
Actually, for a VINYL pool, both numbers are correct.
An Akl of 110 is just about perfect for ANY pool, but it's important to know the ranges:
For a gunite/concrete/plaster/tile pool, the recommend Total Alkalinity range is 80-125 (ok, 120--what's the dif?)
But for a vinyl pool the upper end of the range can go to 200ppm--but it is my personal belief that you are pushing your luck and should consider 180ppm to be the top end of the range.
When T/A is high, then if Calcium goes too high you will get cloudy water quickly. Calcium for concrete should be in the 200-400ppm range, but for vinyl can go from 0 to 500ppm. However, if your Cal is 500 or higher and your alk goes to 200 or higher, clouds will happen. That's not an exact pairing of the numbers, more like a ball-park range.
Due to the nature of concrete pools, and the fact that they can be chemically interactive with the water, unlike vinyl, pool chemistry of these two measures is more important.
No inconsistency here: Vinyl doesn't react with calcium or to tot alk, so different levels are appropriate. There's nothing WRONG with using the concrete/plaster levels for alk and Calcium, but you have a wider range.
On the other hand, when it comes to pH and max chlorine levels, vinyl is FAR more sensative than concrete/plaster and you must be more careful. You can run FC up to 60ppm in a concrete pool but you'll bleach your liner in a vinyl one--and probably weaken it. In a concrete pool, pH can drop well below 6.9, but in a vinyl pool it can soften and wrinkle the liner.
CYA doesn't seem to have ANY effect on either pool.
Carl
Actually, Arch chemical recently did a study about plaster degredation and high CYA levels and they found that high CYA levels (above 100 ppm) CAN damage a plaster pool. Maybe there is hope for that company yet!Originally Posted by CarlD
Retired pool store and commercial pool maintenance guy.
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