CH test never turned blue... went from purple to clear, then yellow

[Killer95Stang]

I have TFP user since the pool was built in 2013. That means I've never had a algae bloom, or water that wasn't clear. My main problems here in Sunny SoCal (LA County) is the hard water. From the beginning, my fill water was 200- 250 right out of the tap. That high CH equates to a build up of CH with almost no splash out or loss of water that isn't evaporation.

Lately, I've been busy, so I've let my testing slack a little. Water is still sparkling, but chemical balance is a little out of whack. Today, I decided I would run a full set of tests, minus the Salt Level and Borates level, since I figure it wouldn't matter that much (SWG is happy and is functioning).

Because of the cold temps of mid to high 40's (yeah, I know, shorts and jackets look funny), I figured my Chlorine level would be high, with the SWG set at 30%. Here's the numbers..

CL = 14.5 Wowzers, a little higher than I figured.
CC = 0 Probably because of the High CL
TCL = 14.5
CYA = 50 - 60 hard to tell,
TA = 90 that is higher than normal for my pool
PH = 7.6 - 7.8 Probably false reading due to the High CL

CH = 950 This is my big problem for today. At about 90 drops, the color was purple, but then just went to clear by 100 drops. That was odd to me, so I just added more drops and it turned to a yellowish green color. I never hit the blue I like I always have in the past.

Taylor test chemicals were all purchased at the beginning of the summer, so I know they are still good.

So far I turned off the SWG, so I can get it back under 7ppm. Then I'll start working on the PH and TA.

Any ideas about the CH test?

 

[mknauss]

*Measuring high CH levels is much easier and more precise if you use a magnetic stirrer.
*The sample may turn purple during the test, or go to blue for a moment and then turn back to red/pink. This is called a "fading endpoint" and is caused by interference from metal ions. If this happens, do the test again, but this time add five drops of R-0012 before adding any R-0010 or R-0011L. Remember to count the initial five drops in the total.
In extreme cases, a fading endpoint may occur even when adding five drops of R-0012 at the start. If that happens, mix pool water with an equal quantity of distilled water, test that, and then multiply the result by two.

The above is from Pool School - Pool School - Calcium Hardness

Try that.

FYI -- you are probably due for a water change. At 1000 ppm + CH, it becomes nearly impossible to prevent calcium scale.

Take care.

 

[JoyfulNoise]

High chlorine levels can compromise the dye. But try this - add about 10 drops or so of the R-0012 first (before any R-0010) and then redo the test. Count all of the R-0012 drops. Metal ions can also interfere with color changes and adding the R-0012 can help sequester them. Also, let the sample warm up to room temp and, if you want, you can store a water sample for a few days to let the FC naturally degrade....a small UV light works well at helping that process along but is not required. I did the natural degradation process a few months back when I wanted to measure nitrogen levels (nitrites, nitrates & ammonia) and that requires zero FC.

 

[Killer95Stang]

Great suggestions.... I'll let my CL go down a little before I run the tests again... You guys are probably right about the water change. I've gotten five years out of my hard water, so I can probably stand to empty and refill. I'll call the water company and I tell them my pool is getting resurfaced or something, so I don't get hammered with the refill cost.

 

[JoyfulNoise]

Great suggestions.... I'll let my CL go down a little before I run the tests again... You guys are probably right about the water change. I've gotten five years out of my hard water, so I can probably stand to empty and refill. I'll call the water company and I tell them my pool is getting resurfaced or something, so I don't get hammered with the refill cost.

I was at 1250+ ppm all last season. I managed it fine with no scale. Just takes a little more diligence on keeping the pH down in the 7.5-7.7 range. I plan to drain and refill in a few months.

Oh, and most water companies only give you a break on a new pool fill; after that, you pay full price. At least that's how our water supplier is....

 

[jseyfert3]

100 drops? You're being hard on yourself! Use a 10 mL sample and multiply drops by 25. That would cut your drops for 1000 ppm CH down to 40.