Rapid decrease in CF and Cloudy with SWG and UV light (Sundance)

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D

DougJack

Gold Supporter
Oct 24, 2024
69
Jackson, WY
Hi, I was making good progress and now things seem a bit off. I have a 1450 liter hot-tub running at 104F. The tub is a Sundance-Optima. It does have a UV lamp. I had the water in balance before I left for two weeks. A friend who is very careful watched the tub while I was gone and recorded the pH and put in 50ml of liquid 12.5% Cl each day. He would measure CF in the morning and it was typically 1.5 - 2.0.

I came home and went into the tub for an hour in evening and didn't put in the Cl. In the morning the CF was zero. I added 75 ml and an hour later it was zero. I continued adding and measuring until I put in nearly a half liter of Cl. Still, after an hour, zero. I thought about that and tested the CYA which was normally close to 25 and it was zero. Aha! I did a little searching and found that it could be oxidized, and that could be accelerated with UV. I added dichlor and got the CYA to 23 and things seemed normal again.

I then decided to install the SWG I had bought and put in enough Diamond salt to get to 2300 ppm of salt (as measured by the Homice probe). I let the jets run for a while, and then waited 5 hours. Then I adjusted the CF to 4ppm and plugged in the Saltron. I measured the CF in an hour and it had dropped to 1.5. 5 hours later it is at 1.0 with most of that being CC.

After I added the salt the water became cloudy. I had never seen that before and it doesn't go away. I'd sure like to see the FC in the average range they talk about and for the water to be clear. Any ideas???

Here are the numbers: ......THANKS IN ADVANCE!!! - Doug

PH 7.5
CYA 22
SALT 2300
CC 0.5-1.0
TA 50
CH 150
BORATES 50
TEMP 104
 
How did you actually measure a CYA of 22?
You can't just guess by the amount of dichlor you added.

No, FC is Free Chlorine.
 
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We aren't big fans of using electronic testers. They have proven to not be as accurate as one might expect.

You may find it better to have a CYA in the 30-40 range. Never let FC fall below minimum based on the FC/CYA Levels. This may require an FC above high end of the target range so FC doesn't go below minimum while using the tub. It is safe to enter the water when FC is between minimum and SLAM levels based on your CYA.

Your signature indicates you have a TF-Pro test kit.
Post a full set of current test results using your TF-Pro.
If CYA falls between two numbers on the vial, round up to the next multiple of 10.

FC
CC
pH
TA
CH
CYA
Salt
Water Temperature

How are you measuring salt content?

How are you measuring borates?
What is your reasoning for adding borates?
 

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proavia said:
We aren't big fans of using electronic testers. They have proven to not be as accurate as one might expect.

You may find it better to have a CYA in the 30-40 range. Never let FC fall below minimum based on the FC/CYA Levels. This may require an FC above high end of the target range so FC doesn't go below minimum while using the tub. It is safe to enter the water when FC is between minimum and SLAM levels based on your CYA.

Your signature indicates you have a TF-Pro test kit.
Post a full set of current test results using your TF-Pro.
If CYA falls between two numbers on the vial, round up to the next multiple of 10.

FC
CC
pH
TA
CH
CYA
Salt
Water Temperature

How are you measuring salt content?

How are you measuring borates?
What is your reasoning for adding borates?
Click to expand...
Here are the results with comments:
PH 7.5 - measured with Homcoice (I'll do a test with the TF-Pro and post it.
CYA 22 - Measured with Pool Lab 2.0, it just showed below 50 with the TF-Pro. I'm getting a smaller diameter tube so that I can use the kit. 10mm should double the sensitivity for the same height, assuming it is linear.
SALT 2300-using the Homcoice - I have the salt reagents coming from TFP
CC 0.5-1.0-using TF-Pro
TA 50-TF Pro
CH 150-TF Pro
BORATES 50-using procedure from JoyfulNoise
TEMP 104-Pool measurement - closer to 102 by my Apple Watch....

I added the borates because of recommendations I found in TFP that indicated better buffering and a "silky" feel for the water as well as a change in index of refraction that made the water sparkle. Before adding the salt we talked ourselves into the feel improvement, the water was very clear, and the pH remained very stable at around 7.6-7.7.
 
DougJack said:
Here are the results with comments:
PH 7.5 - measured with Homcoice (I'll do a test with the TF-Pro and post it.
CYA 22 - Measured with Pool Lab 2.0, it just showed below 50 with the TF-Pro. I'm getting a smaller diameter tube so that I can use the kit. 10mm should double the sensitivity for the same height, assuming it is linear.
SALT 2300-using the Homcoice - I have the salt reagents coming from TFP
CC 0.5-1.0-using TF-Pro
TA 50-TF Pro
CH 150-TF Pro
BORATES 50-using procedure from JoyfulNoise
TEMP 104-Pool measurement - closer to 102 by my Apple Watch....

I added the borates because of recommendations I found in TFP that indicated better buffering and a "silky" feel for the water as well as a change in index of refraction that made the water sparkle. Before adding the salt we talked ourselves into the feel improvement, the water was very clear, and the pH remained very stable at around 7.6-7.7.
Click to expand...
I decided to stop the SWG because my FC was 0 this morning. I added 125ml of 12.5% liquid chlorine and ran the jets for 5 minutes. Then I waited an hour and tested for FC and found 3.0 (should have been 10 or so) and had CC of 1.0.
 
Ahhsomeguy said:
Doug-Jack: When you did the Ahhsome purge what did the water look like? Did you see any discoloration or sticky brownish floating particles? Did you use the blue gel or the liquid?
Click to expand...
We did get sticky brownish particles, especially on the corners. We cleaned everything out with rags and used the wet vac on the jets. I used the liquid. I called AhhSome and talked with support and they recommended the gel as it is a lot cheaper and as long as I have warm water there is no issue with getting it to mix. He said there was zero difference in effectiveness.
 
DougJack said:
Here are the results with comments:
PH 7.5 - measured with Homcoice (I'll do a test with the TF-Pro and post it.
CYA 22 - Measured with Pool Lab 2.0, it just showed below 50 with the TF-Pro. I'm getting a smaller diameter tube so that I can use the kit. 10mm should double the sensitivity for the same height, assuming it is linear.
SALT 2300-using the Homcoice - I have the salt reagents coming from TFP
CC 0.5-1.0-using TF-Pro
TA 50-TF Pro
CH 150-TF Pro
BORATES 50-using procedure from JoyfulNoise
TEMP 104-Pool measurement - closer to 102 by my Apple Watch....

I added the borates because of recommendations I found in TFP that indicated better buffering and a "silky" feel for the water as well as a change in index of refraction that made the water sparkle. Before adding the salt we talked ourselves into the feel improvement, the water was very clear, and the pH remained very stable at around 7.6-7.7.
Click to expand...
I did the pH test with the TF-Pro block about 7.7-7.8, Homcoice 7.65, Pool Lab 7.36
 
DougJack said:
Here are the results with comments:
PH 7.5 - measured with Homcoice (I'll do a test with the TF-Pro and post it.
CYA 22 - Measured with Pool Lab 2.0, it just showed below 50 with the TF-Pro. I'm getting a smaller diameter tube so that I can use the kit. 10mm should double the sensitivity for the same height, assuming it is linear.
SALT 2300-using the Homcoice - I have the salt reagents coming from TFP
CC 0.5-1.0-using TF-Pro
TA 50-TF Pro
CH 150-TF Pro
BORATES 50-using procedure from JoyfulNoise
TEMP 104-Pool measurement - closer to 102 by my Apple Watch....

I added the borates because of recommendations I found in TFP that indicated better buffering and a "silky" feel for the water as well as a change in index of refraction that made the water sparkle. Before adding the salt we talked ourselves into the feel improvement, the water was very clear, and the pH remained very stable at around 7.6-7.7.
Click to expand...
I thought more about the potential effect of the UV. I think it turns on when the filter is running so I set the filter start and stop time for tomorrow a.m. Then I put in 23g of dichlor which should got to 10 ppm of FC (by Pool Math), and should raise the CYA from 23 to 37. I'm letting the jets run for 5 minutes, then I'll measure both the FC and CYA and report.
 
DougJack said:
I thought more about the potential effect of the UV. I think it turns on when the filter is running so I set the filter start and stop time for tomorrow a.m. Then I put in 23g of dichlor which should got to 10 ppm of FC (by Pool Math), and should raise the CYA from 23 to 37. I'm letting the jets run for 5 minutes, then I'll measure both the FC and CYA and report.
Click to expand...
After 5 minutes FC was 7.0, pH 7.7, CYA 32. I'll wait an hour and test again. Still cloudy.
 
So I ran without the filter/UV running for 3 hours and went from FC of 7.0 to FC of 5.5. This is completely different from my previous readings. Just to confirm things I am going to run the filter/UV continuous for an hour and see if the FC does collapse as before. As we have temperatures significantly below freezing here, it is important to keep the filter running and I can either live with the UV being on continuously or remove it. If I learn more, I'm assuming I can put a timer on it to get the UV benefits. In the meantime, I am going to set the CYA for 45ppm and see if I can minimize the impact of UV without making the FC too ineffective. Still cloudy....Are my steps making sense?
 
I lowered the temp to 102F as this should roughly reduce the reaction rate by 6%. I have the CYA at 37ppm now (the Pool Lab seems accurate) - will target 45ppm tomorrow. Salt is 2560 (not a Taylor # yet). I put some SpaGuard Pool Water Clarifier in and the water is clear now. At the current loss rate of FC the Saltron should be able to compensate in 5 hours. We'll see! I'll adjust the pH tomorrow when things stabilize further.
 
Only post results from your TF-Pro as then we are all on the same page. No need for notes.

Explain how the TF-Pro is providing a CYA of "below 50". You should be able to determine if the CYA is 30, 40, 50 or any multiple of 10 all the way up to 100.
The CYA scale on the test tube is non-linear. If the reading falls between any two lines, round up to the larger number. "22" is read as 30.

Please change to imperial units - gallons, ounces, etc. Again, keeps us all on the same page. Someone may see your location in WY and your dosage as US unit, and think you are over dosing.

Suggest you do an Overnight Chlorine Loss Test. This may require you to leave the tub uncovered overnight so the tub can breath and the CC can escape.
Post the results here.

Post results as
FC
CC
pH
TA
CH
CYA
Salt
Water Temperature

Or use PoolMath and link PoolMath to your forum account.
 
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