Delayed FC reading

[Trichef1]

In anticipation of moving away from the Frog cartridge system and to the TFP chlorine method I purchased a Taylor K-2005. When I measure the Free Chlorine the initial reading is very low but over the next 30-60 seconds the reading increases significantly. Should I be using the initial reading or the later one? What is the proper wait-time (if any) for the most accurate reading?
Could the delayed reading be due to the tub chemistry .. I’m still using the Frog system for the next week or so.

 

[Newdude]

Hey chef and Welcome !!!

The K2005 only measures TC, and not accurately at that (as you've seen). Besides the accuracy issues, TC is a junk metric because 5+0=5 and 2+3=5 tell two completely different stories, while the 5 (TC), is a meaningless part of both stories.

You need to purchase a k-1515 fas/dpd kit on the side to complete your k2005.

Then once you have that, the frog system will be the root cause of the test issues. (FC shows up as CC, IIRC) and it can't really be tested.

 

[proavia]

Welcome to TFP!

When taking the FC reading - measure out the water sample, add the drops, mix and take the reading.
Most likely, letting the sample sit will allow any CCs to affect the reading.
FC + CC = TC
FC - Free Chlorine
CC - Combined Chloramines
TC - Total Chlorine

With a K2005 test kit, you need to add the K1515 test kit to use the TFP methods.
Test Kits Compared

Have you downloaded the PoolMath app yet?

 

[JamesW]

Are you talking about the pH or chlorine?

The thread title says pH, but the post says FC?

A delayed pH reading is usually high chlorine interference.

A delayed FC reading with a Frog is probably due to DMH.

The Frog uses DMH for chlorine, which is like CYA, but the DMH-chlorine bond is stronger and it results in a slow FC reading or a CC reading instead of a FC reading.

 

[JamesW]

I don't know why, but it does.

If you are using the Frog system, and you do a standard FAS/DPD test your CCs are going to show off the charts. It just does.

This is from the Smartchlor manual itself - https://www.kingtechnology.com/wp-c...manager-files/@ease-In-Line-System-Manual.pdf

"SmartChlor is self-regulating. However, if you use standard test strips, it may appear that total chlorine is higher than the free chlorine. No worries—the strip is measuring the SmartChlor reserve, which will shift to free chlorine as needed. Please always use the FROG @easeTest Strips that were included with your System."

So it appears that the "SmartChlor Reserve" shows up as CCs

Chlorine has an equilibrium with CYA and DMH.

Chlorine dissociates from the CYA during the FASDPD test, so it tests as free chlorine.

Maybe chlorine binds much more strongly to DMH than it binds to CYA?

It might require waiting for a few minutes for the Chlorine to unbond from the DMH.

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[Trichef1]

Are you talking about the pH or chlorine?

The thread title says pH, but the post says FC?

A delayed pH reading is usually high chlorine interference.

A delayed FC reading with a Frog is probably due to DMH.

The Frog uses DMH for chlorine, which is like CYA, but the DMH-chlorine bond is stronger and it results in a slow FC reading or a CC reading instead of a FC reading.

JamesW … I’m talking about FC .. guess i was still sleeping when i created the post hence the mixed-up thread title. So would you suggest that I wait until I switch completely from the frog system to the TFP chlorine system to even try to get an accurate and/or meaningful FC reading? Also, it was suggested that I get the K-1515 kit in addition to the K-2005. Would you confer with that or do you feel the Chlorine readings from the k-2005 will be sufficient once the spa chemistry is switched?

 

[JamesW]

You should get the FAS-DPD test kit.

You should measure the CC levels with your current and new FAS-DPD kit.

 

[JamesW]

Do the FC test and then immediately do the CC test to see how much of each level you have.

In my opinion, the Frog is based on questionable technology.

The silver levels are almost impossible to maintain because the silver will form an insoluble precipitate with chloride or bromide.

If you have chloride or bromide in the water, the silver levels will be in the low ppb (parts per billion) levels.

All water has salt (sodium chloride) unless it is RO or distilled.

Adding chlorine or bromine adds chloride or bromide, so the silver is going to be significantly reduced.

Frog postulates that DMH protects the silver, but I think that the hypothesis is completely unproven.

In my opinion, the test data related to the silver efficacy is questionable at best.

Even if the product might work in theory in controlled conditions, it is less likely to work in the real world where there are many variables that can affect the performance of the product.

Products need to be robust in performing under a variety of real world conditions to provide reliable protection from pathogens, bacteria, viruses, fungus, mold etc.

 

[JamesW]

The maximum amount of silver chloride that you could dissolve into 1 liter of distilled water is about 1.91 milligrams.

You would get about 1.435 ppm silver and about 0.47163 ppm chloride.

(0.0000133041M) x 107.8682 = 0.00143508931 grams per liter = 1.435 ppm silver

(0.0000133041M) x 35.45 = 0.00047163034 grams per liter = 0.47163 ppm chloride = 0.77749 sodium chloride.

However, as the salt level increases, the silver has to decrease.

So, if the salt level goes to 100 ppm, then the silver level has to drop to 11 ppb (parts per billion)

128.62 times the salt = 100 ppm sodium chloride.

128.62 times less silver = 11 ppb silver.

1.435 ppm silver x 0.77749 sodium chloride = 1.1157

ppm silver x ppm sodium chloride = 1.1157

ppm silver = 1.1157/ppm sodium chloride

At 500 ppm salt, the silver will be at 0.00223 ppm or 2.23 ppb.

ppb silver = 1,115.7/ppm sodium chloride.

 

[Trichef1]

Great information James … Thank you for the support