PoolMath vs Acid Demand and Base Demand

[acpie360]

According to Taylor K-2006, you'll test either Acid Demand or Base Demand first, then compare the drop reading to a treatment table to determine the amount of Muriatic Acid or Soda Ash needed to decrease or increase pH level. However, if you use PoolMath, it doesn't seem to require either one of these two inputs, i.e., Acid Demand or Base Demand. Why is that?

 

[Richard320]

Poolmath uses the TA level as well.

If you're off the scale at either end, the demand tests are pretty handy. Say you're at 8.7 pH. All you see is 8.2. You won't hit your target using poolmath because all you know is that it's 8.2 or higher.

Once you're in range, poolmath saves a lot of extra work. No extra drops to count, no math.

 

[acpie360]

Richard, thanks for the explanation. On an unrelated subject - I assume you and I may have similar weather pattern. What CYA number do you think is the best for our region? Mine is at 35 right now and it seems my FC drops about 1.4ppm per day on average. I usually target for 4ppm in the night, add about 1/2 gallon of bleach. 24-hours later the FC reads around 2.6. The CC is always less than 0.2, which means my breakpoint chlorine is around 2. Correct?

 

[Richard320]

Richard, thanks for the explanation. On an unrelated subject - I assume you and I may have similar weather pattern. What CYA number do you think is the best for our region? Mine is at 35 right now and it seems my FC drops about 1.4ppm per day on average. I usually target for 4ppm in the night, add about 1/2 gallon of bleach. 24-hours later the FC reads around 2.6. The CC is always less than 0.2, which means my breakpoint chlorine is around 2. Correct?

My CYA is 40-50. I pump water out periodically to lower the CH buildup and lose some CYA that way, but then I use pucks when I leave town and it goes back up.

I don't know where you get this breakpoint stuff from. I know nothing about that.

 

[JoyfulNoise]

Richard, thanks for the explanation. On an unrelated subject - I assume you and I may have similar weather pattern. What CYA number do you think is the best for our region? Mine is at 35 right now and it seems my FC drops about 1.4ppm per day on average. I usually target for 4ppm in the night, add about 1/2 gallon of bleach. 24-hours later the FC reads around 2.6. The CC is always less than 0.2, which means my breakpoint chlorine is around 2. Correct?

The 10X breakpoint chlorination rule for CCs is totally wrong. See this post - Certified Pool Operator (CPO) training -- What is not taught Because they don't normalize the units of concentrations involved to the same chemical species (ammonia measure as ppm as N while chlroamines are ppm of Cl2), the scale factor is totally botched up. At most, the multiplication factor is 5X for some amine containing species, while others can be as low as 3X.

At the end of the day, it doesn't really matter as you will add enough FC far in excess of any CCs that are around and there's no danger from CCs even when they are elevated (say above 1.0ppm). Simply keep your chlorine at target levels and the CCs will be destroyed. Trying to chase after CCs is a futile task as they will always fluctuate a little here and there. There is no danger from CCs in a clear and clean swimming pool.

 

[acpie360]

The CPO material is a bit too deep for me Anyway, I got the 10X rule from reading the booklet, titled Pool & Spa Water Chemistry, that comes with the Taylor K-2006 kit. This is what it says:

Thanks to all you guys for putting this right.