A=Using the Acid Demand Test

[Bobbystone]

So what's the relationship per drop of the acid demand test? Is each drop count for one unit of PH, ie 7.8 to 7.6? Or is there a formula to convert the number of drops to the amount of acid needed for a given volume of water (30K in my case)

Thanks!

 

[jblizzle]

All the test kits I have seen have a chart for what the number of drops mean (I do not know off-hand).

Alternatively, you can use the http://www.poolcalculator.com to tell you how much acid to add based on current pH and desired pH inputs.

ETA: Make sure you input your pool size at the top though

 

[Durk]

Assuming it's a Taylor K-200x kit, one drop for a 30Kgal pool indicates a need for 27.48 fluid oz.*, or a little over a fifth of a gallon. Unlike many on this board, I am a fan of the Acid Demand because I don't do well with those shades of red at 7.6+. So just add drops until the color is where you would like to get to and plunk in a fifth of a jug per drop plus a shot. Works great for me and no need for a computer at the pool. I also have a pitcher marked in ppm to use with LC (or bleach, just double the dose). KISS. I only use Pool Calculator for my every other Sunday full test routine.

*=from p. 54 of the Taylor Water Chemistry booklet Part #2004B that came with my ancient K-2000. I'm sure there is a newer one now.

 

[CaOCl2]

The number of drops required depends on the TA of the water sample. The higher the TA the more drops you'll need. So there's no direct relationship.
When you think about it, the Taylor TA test is actually an Acid Demand test as well, you're figuring out how many drops of acid you need to reach pH 4.5.
The pH Acid Demand works in a similar way, you have your pH indicator (R-0004) and your titrant (R-0005), but _you_ determine the endpoint.
You can say that TA represents the quantity of acid required to reach a certain pH.