FC vs. Stock Tank (longer and less entertaining than the Notorious/Money fight)

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matthys333

matthys333

0
Aug 2, 2017
33
Jacksonville, Florida
I've been having an ongoing battle keeping my FC over 2 from day to day.

Having a stock tank which is much smaller and different material (galvanized steel) than 99.9% pools in this forum, makes me the pioneer of finding the best chemical balancing for this pool.

Good News is that all the levels are good every week that I do the full TFTestKit.

Bad News is my FC drops too much from day to day.

My theory was between only having about 750 gallons, being in direct sunlight dawn to dusk, and having a metal surface that reflect rays, my FC just gets eaten like Mayweather did with McGregors punches.

So for the past few weeks, I've been upping my CYA by 10 each time. Started off at around 20, went to 30, then 40, and this past Friday added enough to bring to 50. Didn't test again, but FC still dropped below 2 (.5 to be exact). So added enough for 60 just now.

This morning's FC test was encouraging with the .5 FC as it pretty much usually was at 0 every day leading up. (yes I've shocked and did ONFC test before and it's not contaminants)

My added theory is that being as small as it is, there's water being splashed out, thanks toddlers, and refilled occasionally. Plus the Sunshine State's frequent rainfall that adds to it.

I'm not sure what else to do except keep bringing up CYA until daily FC does not drop under 2 and settle with the fact that my pool will be a bit more high maintenance with the specs listed above.

Any thoughts?
 
My thoughts are that since you have consistently been letting the FC drop below the minimum for your CYA according to the [FC/CYA][/FC/CYA], there is now likely stuff growing that is helping to consume your FC.

Stop raising the CYA at this point, get a good read and then raise the FC up some and perform the Overnight Chlorine Loss Test to see if you have high losses at night.

If you do, the you need to follow the SLAM Process process.
If you do not lose a lot of FC, then start making sure you are raising the FC high enough each day so it does not drop below the minimum.
 
How does the water look? Is it crystal clear, or maybe a bit cloudy? You could run an overnight chlorine loss test (OCLT) and see if anything other than the sun's UV rays are eating your chlorine. After the sun is off your pool in the evening, dose your pool to a FC level of 8 and and retest within 30 minutes and record the actual FC reading. Then, set your alarm for early in the morning (before the pool gets any sunshine) and re-test FC again. If you lose 1 PPM or less, you know that they're nothing in your water that is eating your FC. If you don't, it's time to SLAM your pool.

Pool School - SLAM - Shock Level And Maintain
 
jblizzle said:
My thoughts are that since you have consistently been letting the FC drop below the minimum for your CYA according to the [FC/CYA][/FC/CYA], there is now likely stuff growing that is helping to consume your FC.

Stop raising the CYA at this point, get a good read and then raise the FC up some and perform the Overnight Chlorine Loss Test to see if you have high losses at night.

If you do, the you need to follow the SLAM Process process.
If you do not lose a lot of FC, then start making sure you are raising the FC high enough each day so it does not drop below the minimum.
Click to expand...

I've been using the PoolMath app to let me know every day how much chlorine to add. Why it drops like it does, I don't get. This happened after I went through the whole SHOCK process and overnight FC test a few weeks ago. I test every day and add chlorine, so unless I do it 2-3X a day, I'm not "letting" anything happen. Just going by what is taught here on pool maintenance. If my pool requires me to test and add chlorine more than once a day, it's no longer a troublefreepool, in my opinion.

I'm testing the water in a minute and then probably doing the overnight test, just to rule out. Then go from there I suppose.

- - - Updated - - -

Demegrad9 said:
What FC level do you bring it up to everyday?
Click to expand...

What PoolMath recommends....5ppm
 
DeanP66 said:
How does the water look? Is it crystal clear, or maybe a bit cloudy? You could run an overnight chlorine loss test (OCLT) and see if anything other than the sun's UV rays are eating your chlorine. After the sun is off your pool in the evening, dose your pool to a FC level of 8 and and retest within 30 minutes and record the actual FC reading. Then, set your alarm for early in the morning (before the pool gets any sunshine) and re-test FC again. If you lose 1 PPM or less, you know that they're nothing in your water that is eating your FC. If you don't, it's time to SLAM your pool.

Pool School - SLAM - Shock Level And Maintain
Click to expand...


Pool is crystal clear...no issues. Wouldn't even know something is wrong without the daily testing. The first time I realized the FC dropped like it did when I first started doing the methods here, I did go through the SHOCK and overnight test. The FC only dropped 1 and the CC was only .5. So nothing was in the water, but the FC still dropped daily.

This is why I'm more convinced about the strength of the sun all day on a small steel pool, than any contaminants. But I'll do another overnight test tonight, if the FC tests low again today. And see how it goes.

No one here that I know of has a stock tank pool, so it seems that most recommendations are based around the usual materials and sizes of pools. The nature of my pool is different, so we have to keep that in mind.
 
*Update*

So did my Taylor K-1000 test just now and surprisingly, the FC was at around the 3-4ppm mark. So finally it was staying up.

HOWEVER.....

I tested the CYA just out of curiosity to see what level it was that it finally kept the FC up. And it was at 100. Which is nuts because I never added enough CYA for it to jump that high up.

So now what?

I assume it has to be lowered again. And that means to drain some water and refill it, yes?

Then I'm back at the FC challenge.

It's a lose lose situation...haha
 
*Update 2*

Since the first CYA test said 100 for some reason, I ended up doing the diluted CYA test to see how far over 100 it actually was.

Surprisingly, it showed 30, which means 60...which is where it was supposed to be from my CYA adding calculations.

I poured the solution back in the squeeze bottle to do a double take. It was 30 again. Weird.

So I did the normal CYA test again. And it showed 60, not the 100 initially. What the...? Maybe I didn't mix the first solution enough or something?

Anyway, this means my CYA is at 60 and after I brought FC up to 5ppm yesterday, it only dropped to 3.

BUT, I just realized I didn't update my CYA number in PoolMath for FC calculation, from 40 to 60, so it seems I didn't bring up the FC enough yesterday.

So today, I'll bring it up to the recommended 7ppm today, and see where it's at tomorrow. If it stays around 5ppm, I'll be good to go. If it drops below, I'll do an overnight test.

Hopefully, I can find an end here soon.
 
The target is a range not an absolute. The most important thing is to raise it high enough such that it does not drop below the minimum for your CYA by the next time you test.
 
My opinion only. You need to verify the Pool Math calculation and test your FC an hour after the chlorine application otherwise your FC target is only an educated guess and your 12 or 24 hour FC loss that has your attention is only an estimation. Verify your FC by testing do not rely on calculations alone until you know how your system responds. Once you have verified results you can cut back on the frequency of the testing and get into the trouble free zone. Start with the basics and verify you have a problem before pushing your CYA much higher. Sanitizer strength should not be assumed as it can be altered by age, temperature, sunlight, production error, etc.
 

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Jason has it right. It's ok to raise a little above target to make sure you don't end up under the minimum each day, especially given your very different pool design. :)

You still will want to go ahead and run an OCLT - having a warm pool below minimum that frequently puts up warning flags. "Crystal clear" doesn't mean "algae/bacteria free".
 
matthys333 said:
Anyway, this means my CYA is at 60....

So today, I'll bring it up to the recommended 7ppm today, and see where it's at tomorrow. If it stays around 5ppm, I'll be good to go. If it drops below, I'll do an overnight test.
Click to expand...

There is no reason you couldn't raise FC to 10-12ppm when you dose to be sure the FC stays above your minimum. There's no reason to cut so close to the minimum value if you find you are losing a lot of FC per day.
 
DeanP66 said:
At CYA of 60, your minimum FC is 5 and the target is 7-9 PPM. You should dose up to 9 so you don't fall below the minimum during the day.
Click to expand...

Dean is spot on here. You want to dose the pool to the high end of the target to make sure you don't get anywhere near that minimum. The "minimum" you should be attempting to maintain is 7 - leave that last 2ppm as a buffer just in case something goes wrong.
 
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