High FC

[synapsid]

Hello friends,

Still in my first summer of owning a pool and I’ve learned a lot from TFP. Some recent rain, a lot of splashout and maybe a touch of inattentiveness and my test results seem out of whack. I’m re-reading the chemistry basics and I have the pool math app but I would appreciate any advice on these results from my Taylor k-2006c:

FC 15.5
Total combined Cl 1.5
CYA 45
pH 7.0
TA 40
Ca hardness 40
Salt 3400 (2900 reading on SwG)

The FC has been reading high since i started testing maybe 2 months ago. I have the Hayward aqua trol at 70% output and run the pump around 8 h a day. It’s been in the high 80s-90s here on Long Island.

Thanks for any advice you can provide!!

 

[Bperry]

Hello friends,

Still in my first summer of owning a pool and I’ve learned a lot from TFP. Some recent rain, a lot of splashout and maybe a touch of inattentiveness and my test results seem out of whack. I’m re-reading the chemistry basics and I have the pool math app but I would appreciate any advice on these results from my Taylor k-2006c:

FC 15.5
Total Cl 1.5
CYA 45
pH 7.0
TA 40
Ca hardness 40
Salt 3400 (2900 reading on SwG)

The FC has been reading high since i started testing maybe 2 months ago. I have the Hayward aqua trol at 70% output and run the pump around 8 h a day. It’s been in the high 80s-90s here on Long Island.

Thanks for any advice you can provide!!

Are you using the FAS-DPD test for chlorine? (Powder and drops) It gives you FC and CC. Total chlorine is the sum of FC and CC so it’s not possible for your total chlorine to be lower than the FC.

FC of 15.5 isn’t bad with a CYA of 50ppm as you’re still under SLAM level. But you can certainly turn it down a bit so it stops climbing (assuming you’re testing with the right stuff)

 

[proavia]

Lower the SWG percentage or reduce pump run time.

If the CYA result is in between the lines on the test vial, round up to the next larger number.
CYA result of "35" is rounded up to CYA 40.
Dose chlorine accordingly using FC/CYA Levels
Shoot for the higher side of the target range.

Be aware that pH reads falsely high with FC > 10.

 

[Mdragger88]

Here’s about what your cell is producing at those settings

That’s not set incredibly too high (average fc loss is usually between around 2-4 ppm/day - less in the shoulder seasons & on the higher end in the peak of summer.
You may just turn it off for a day then dial it back a notch.
Note that the ph test is inaccurate at fc levels above 10ppm.
Your ta is a tad low - perhaps you over did your last acid addition due to the invalid ph test.
You can use a smidge of baking soda to get that to 50ppm. Go easy as to not overdo it. Use
PoolMath to calculate amounts.
It’s also possible that your pool volume is a little off - your full signature says a different volume than your banner. How deep is your pool’s water level?

 

[synapsid]

Are you using the FAS-DPD test for chlorine? (Powder and drops) It gives you FC and CC. Total chlorine is the sum of FC and CC so it’s not possible for your total chlorine to be lower than the FC.

FC of 15.5 isn’t bad with a CYA of 50ppm as you’re still under SLAM level. But you can certainly turn it down a bit so it stops climbing (assuming you’re testing with the right stuff)

Thanks- yes , I used the FAs-DPD protocol. Two level scoops of the powder in 10 mL of water from 1 foot below surface. Then it took 31 drops to clear it; x0.5=15.5 and I recorded that as FC.

The second part of this test I don’t understand too well but when I added the next reagent it turned pink again within 3 drops.

I cranked the SWG down, will check again once the sun has burned some chlorine off.

 

[synapsid]

Here’s about what your cell is producing at those settings
View attachment 528800
That’s not set incredibly too high (average fc loss is usually between around 2-4 ppm/day - less in the shoulder seasons & on the higher end in the peak of summer.
You may just turn it off for a day then dial it back a notch.
Note that the ph test is inaccurate at fc levels above 10ppm.
Your ta is a tad low - perhaps you over did your last acid addition due to the invalid ph test.
You can use a smidge of baking soda to get that to 50ppm. Go easy as to not overdo it. Use
PoolMath to calculate amounts.
It’s also possible that your pool volume is a little off - your full signature says a different volume than your banner. How deep is your pool’s water level?

Thanks. I’ve never been 100% sure of the volume of this pool. It’s 15‘ x 24‘ oval and currently 44 inches deep. I will add some baking soda and keep watching. Glad to see many saying I’m not too far out of range!

 

[proavia]

Before you add baking soda...
When you do the TA test, continue to add drops until the color no longer changes. Subtraft the last drop that does NOT change the color.

If that is how you already do the test, then add a little baking soda to bump the TA up 10-20 ppm.

 

[Bperry]

Thanks- yes , I used the FAs-DPD protocol. Two level scoops of the powder in 10 mL of water from 1 foot below surface. Then it took 31 drops to clear it; x0.5=15.5 and I recorded that as FC.

The second part of this test I don’t understand too well but when I added the next reagent it turned pink again within 3 drops.

I cranked the SWG down, will check again once the sun has burned some chlorine off.

Read through the instructions again. The second part of the test you add 5 drops which makes it pink again. Then you add the r0871 again counting how many drops it takes to go clear again. Divide the drops by 2 and record the result as CC.

 

[synapsid]

Read through the instructions again. The second part of the test you add 5 drops which makes it pink again. Then you add the r0871 again counting how many drops it takes to go clear again. Divide the drops by 2 and record the result as CC.

Sorry, that IS what I did. It took only 3 drops to clear the second five drops, that’s how I got 1.5. I still think I must be doing something wrong to get that second result so low. I will test again.

 

[Getitrite]

Sorry, that IS what I did. It took only 3 drops to clear the second five drops, that’s how I got 1.5. I still think I must be doing something wrong to get that second result so low. I will test again.

Using 10 mL sample is #drops X .5 25 mL sample is #drops X .2 ? A low CC is a Good Thing.

 

[reggiehammond]

1.5 CC is a bit high for a pool in summer sun.

Have you seen any evidence of algae? Dust on pool floor, cloudiness or visible spots?

 

[proavia]

Sorry, that IS what I did. It took only 3 drops to clear the second five drops, that’s how I got 1.5. I still think I must be doing something wrong to get that second result so low. I will test again.

A CC of 1.5 can be problematic. It should be 0 or 0.5

After completion of the FC part of the test, are you immediately adding the 5 drops of R-0003 and then the R-0871 or are you waiting more than 5-10 seconds to do either?

 

[Bperry]

Sorry, that IS what I did. It took only 3 drops to clear the second five drops, that’s how I got 1.5. I still think I must be doing something wrong to get that second result so low. I will test again.

Ok. Then the only thing wrong is the label you have it. It’s CC and not TC. And ideally it should be zero. If it’s 1.5, you have some organic contaminants. Time to SLAM.

 

[synapsid]

A CC of 1.5 can be problematic. It should be 0 or 0.5

After completion of the FC part of the test, are you immediately adding the 5 drops of R-0003 and then the R-0871 or are you waiting more than 5-10 seconds to do either?

Definitely more than 10 seconds.

 

[synapsid]

Ok. Then the only thing wrong is the label you have it. It’s CC and not TC. And ideally it should be zero. If it’s 1.5, you have some organic contaminants. Time to SLAM.

Thanks, sorry for the error. I have edited my original post to reflect cc not TC.

 

[Mdragger88]

Definitely more than 10 seconds.

If the sample is allowed to sit after completion of the first (fc) part of the test the sample will turn pink again thus requiring more drops to turn it back clear - this can lead to a falsely high result
Try again quickly proceeding to the 2nd part of the test

 

[synapsid]

If the sample is allowed to sit after completion of the first (fc) part of the test the sample will turn pink again thus requiring more drops to turn it back clear - this can lead to a falsely high result
Try again quickly proceeding to the 2nd part of the

1.5 CC is a bit high for a pool in summer sun.

Have you seen any evidence of algae? Dust on pool floor, cloudiness or visible spots?

no evidence of algae. I am suspecting a falsely elevated test based on what others have said here but I will definitely repeat the test. Thanks!

 

[proavia]

Definitely more than 10 seconds.

That may be part of the issue.
No need to let it sit after the FC portion is complete. Just remember how many dropsofR-0871 you added and get right on to the CC part of the test.
As soon as the FC part of the test is complete, add the 5 drops of R-0003. If even the slightest shad of pink, start adding the R-0871 until the solution goes clear again.

When both are done, note the number of drops for the FC test - if using the 10ml sample of pool water, divide number of drops of R-0871 by 2. That gives you the FC level. If 15 drops of R-0871, FC is 7.5
Do the exact same with the number of drops for the CC test - 10ml starting sample - 3 drops of R-0871 is 1.5 CC.

When adding R-0871, time between drops should be about 1 second.
Hold bottle perfectly upright.
Let drops fully form on the tip and drop from their own weight - do not force the drops off.

Are you using a SpeedStir? If not, seriously consider getting one. Makes testing much easier and consistent.
Use it for all your testing. It also makes the salt test easier.

 

[synapsid]

That may be part of the issue.
No need to let it sit after the FC portion is complete. Just remember how many dropsofR-0871 you added and get right on to the CC part of the test.
As soon as the FC part of the test is complete, add the 5 drops of R-0003. If even the slightest shad of pink, start adding the R-0871 until the solution goes clear again.

When both are done, note the number of drops for the FC test - if using the 10ml sample of pool water, divide number of drops of R-0871 by 2. That gives you the FC level. If 15 drops of R-0871, FC is 7.5
Do the exact same with the number of drops for the CC test - 10ml starting sample - 3 drops of R-0871 is 1.5 CC.

When adding R-0871, time between drops should be about 1 second.
Hold bottle perfectly upright.
Let drops fully form on the tip and drop from their own weight - do not force the drops off.

Are you using a SpeedStir? If not, seriously consider getting one. Makes testing much easier and consistent.
Use it for all your testing. It also makes the salt test easier.

Great advice, I think I will get a speedstir. I can tell I'm introducing inaccuracy by "swirling" that double tube with the flat back.

 

[reggiehammond]

Once you have a speedstir, you'll wonder how life was possible without it.
I think it should be part of the standard kit. It's key to getting accurate results.