Chemical quantities

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Viperscorpio

Well-known member
May 25, 2019
69
Arizona
So I've had a pool for a few months now, and have been following the TFP method every since I started, and everything has been great! The pool is always sparkling, thanks!

Now I'm wondering if the quantities of chemicals I'm using sounds about right...
I'm in Gilbert, Arizona, so we get lots of sun, and the temps have been over 100. My particular pool does get quite a bit of shade in the late afternoon, however.

It's 13k gallons, and I'm going through about 48oz of chlorine/day, and need about 8oz of 29% acid/day to maintain a good FC level and pH.

CC has consistently been 0
CYA - when I filled my pool I added enough for 30ppm, but I tested, i could still barely make out the dot, so I added about 10ppm, and yet, I still am able to see the dot when it's at the 30ppm mark. I'm hesitant to add more before checking here first, and if my chlorine consumption sounds about right, I'll just accept it :)

Thanks!
 
Post a complete set of tests in format

FC
CC
pH
TA
CH
CYA
WATER TEMP
CSI

What pH are you targeting!
 
In addition to Allen's request for a complete set of test results.......

With a CYA of less than 30, your chlorine is going to burn off pretty quickly - so 48 ounces a day may be close to normal for your pool. As a comparision, I'm in Chandler (just west of you), 12,300 gallons, CYA of 50 - I use 48-64 ounces of 12.5% chlorine every other day, based on pool load (swimmers, debris).

If you are at less than 30 ppm CYA, add enough to get to 50 ppm. Also, when doing the CYA test, test outside, do not stare at the dot - just glance to see if its there - and hold the vial at waist level with your back to the sun.
 
FC 4
CC 0
Ph7.5
TA 80
CH 250
CYA 40ish
Temp 90
CSI? Not sure what this is

TA, CH, and CYA readings are from last week. I'll also retest those in the AM. I'll also be sure to follow the method above when checking the cya. I'm targeting 7.4 for pH.
 
CSI is calcium saturation index. Anything excessively positive could cause scaling on plaster, tile, or swg cell. Anything excessively negative could cause deterioration of the plaster and grout lines. All your numbers will contribute - some more than others.
 
Here's my numbers as of 5 minutes ago

FC 2.5
CC 0
pH 7.2
TA 75
CH 250
Temp 90F
CYA ~30
CSI -0.45

So, regarding the pH, when I first filled by TA was high (120s), so I was targetting a low pH to bring that down over time, and then figured to bring it up to 7.4 or 7.5 (middle of the range)

For CYA I just did a glance at it with my back to the sun, as directed, and could clearly make out the dot at 40, and still barely see it at 30. When I filled my pool I added enough for 30ppm, and then a week later added enough for 10 additional PPM...not sure why I'm still reading so low. I used pool math for the quantities, and I used the liquid stuff (because I already had some given to me, and then just needed a little more).
 
In the valley you should not operate a pool with a CYA of less than 50ppm, it's just too low and you are losing a good portion of your chlorine to UV extinction. I suggest you keep your CYA at a minimum of 50ppm. As a comparison, I have an SWG pool and consistently try to keep my CYA up at 80-90ppm as that makes the chlorine loss from sunlight very low. Obviously I have to maintain a slightly higher FC level so that my FC/CYA ratio is 5% but my FC loss is very low so my SWG is more than able to maintain those levels. When manually dosing, you need to use a higher FC/CYA ratio of 7.5%.

Your fill water, like all fill water in the valley, will be very hard from both a calcium hardness (CH) concentration as well as carbonate alkalinity. If you are not filling the pool from a softened water tap, I suggest you consider that. Keeping your CH at the lower levels will allow you to achieve the correct CSI for your pool while maintaining a TA and pH at higher levels which is more in line with the natural TA and pH levels found in your fill water. When you try to artificially keep your pH and TA low, you are fighting a losing battle against the fill water that you are adding everyday to the pool. So, what you want to do is maintain a balanced CSI (zero or slightly negative) with a CH on the low end so that your pH and TA can match your fill water TA/pH. This will reduce the frequency of acid addition.
 

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@Viperscorpio

A&M Corsons - McQueen and Warner - 16.99 for 4 gallons of 12.5%. Comes in a yellow crate, which you pay a one time deposit on. They also have muriatic acid in a 4 pack crate, but I don't remember the price.

Other options are Walmart, HD and Lowes for 10% liquid chlorine.
 
@duraleigh good call! I checked my fill water, and it's CH is just 10-20ppm (was barely red to begin with), and the TA was at 110.

I suspect that spicket to which the auto-fill is plumbed may be plumbed to the water softener. When I did the drain/refill, I filled from two separate hoses to speed things up. I haven't tested the other one, but it's possible that the one on the other side of the house is not softened, resulting in the lower CH. I'll test the other tomorrow.
 
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