Rain getting heavy, pool filling up

[JoyfulNoise]

Just to clarify - the FC and CYA levels were not determined by “trial & error” they are an exact ratio. For non-SWG pools, the FC/CYA ratio is 7.5%. For SWG pools, the FC/CYA ratio is 5%. If you you look at TFPs recommended levels chart, you can do the math and see that the FC/CYA ratio is constant.

Why is it this way?

About 20 odd years ago, in the late 90’s, a commercial and residential pool operator by the name of Ben Powell noticed a trend in the pools he managed and care for. No matter what the absolute values of CYA or FC were, those pools that got recurring algae blooms and those pools that stayed clear always seemed to obey a ratio - when the FC/CYA ratio fell below a certain value, algae would almost always follow. Ben started an internet newsletter and listserv (before websites were all the rage) called Pool Solution Inc where he shared his many pool care tips with anyone that wanted help. This later morphed into The Pool Forum where he routinely posted under the screen name PoolDoc. There he posted Ben’s Best Guess Guide. It had some very wide ranges but it basically proved to work in any pool that used it. Ben then met up with Richard Falk (aka, chem geek or perhaps Richard emailed Ben, who knows...) and Richard set about to figure out the chemistry of cyanuric acid and chlorine. Richard then studied several scientific papers on the topic of CYA from the 1970’s (!!!) where he found the chemical data he needed to build a mathematical model of the chlorine-cyanurate equilibrium chemistry. Richard put the hard math and science behind Ben’s discovery by showing the a constant FC/CYA ratio yields a constant active chlorine level (hypochlorous acid which is the sanitizing and powerful oxidizing form of chlorine in water) and it is that active chlorine level which determines if water remains sanitary and algae-free. Richard calculated that a 7.5% ratio would yield the correct amount of active chlorine to keep swimmers safe and comfortable in a pool. So, while trial and error (Ben) revealed a possible solution, it was hard science and math (Richard) that figured out what the correct ratio is.

Just recently it has been announced that the CDC will release a new version of its Model Aquatic Health Code (MAHC) that will finally contain a recommendation that FC varies with CYA rather than being a static value. Richard has worked for over a decade trying to get the CDC’s MAHC committee to see this important truth and it is finally happening....and to think it only took 50 years for the government to recognize the science of CYA that’s been around since the 1970’s....

 

[Dirk]

Shh! Super heros must keep their true identity a secret! :batman:

 

[Dirk]

Just to clarify - the FC and CYA levels were not determined by “trial & error” they are an exact ratio. For non-SWG pools, the FC/CYA ratio is 7.5%. For SWG pools, the FC/CYA ratio is 5%. If you you look at TFPs recommended levels chart, you can do the math and see that the FC/CYA ratio is constant.

Why is it this way?

About 20 odd years ago, in the late 90’s, a commercial and residential pool operator by the nane of Ben Powell noticed a trend in the pools he managed and care for. No matter what the absolute values of CYA or FC were, those pools that got recurring algae blooms and those pools that stayed clear always seemed to obey a ratio - when the FC/CYA ratio fell below a certain value, algae would almost always follow. Ben started an internet newsletter and listserv (before websites were all the rage) called Pool Solution Inc where he shared his many pool care tips with anyone that wanted help. This later morphed into The Pool Forum where he routinely posted under the screen name PoolDoc. There he posted Ben’s Best Guess Guide. It had some very wide ranges but it basically proved to work in any pool that used it. Ben then met up with Richard Falk (aka, chem geek or perhaps Richard emailed Ben, who knows...) and Richard set about to figure out the chemistry of cyanuric acid and chlorine. Richard then studies several scientific papers on the topic of CYA from the 1970’s (!!!) where he found the chemical data he needed to build a chemical model of the chlorine-cyanurate equilibrium chemistry. Richard put the hard math and science behind Ben’s discovery by showing the a constant FC/CYA ratio yields a constant active chlorine level (hypochlorous acid which is the sanitizing and powerful oxidizing form of chlorine in water) and it is that active chlorine level which determines if water remains sanitary and algae-free. Richard calculated that a 7.5% ratio would yield the correct amount of active chlorine to keep swimmers safe and comfortable in a pool. So, while trial and error (Ben) revealed a possible solution, it was hard science and math (Richard) that figured out what the correct ratio is.

Just recently it has been announced that the CDC will release a new version of its Model Aquatic Health Code (MAHC) that will finally contain a recommendation that FC varies with CYA rather than being a static value. Richard has worked for over a decade trying to get the CDC’s MAHC committee to see this important truth and it is finally happening....and to think it only took 50 years for the government to recognize the science of CYA that’s been around since the 1970’s....

JN, that is amazing! Thank you so much for that excellent explanation. What I was remembering, and relaying, was Ben's "trial and error/best guess" efforts and had left out Richard's work! Thanks for correcting me. The problem still remains of accurately calculating/knowing the water's volume, to be able to introduce the proper amount of CYA and chlorine, and also being able to somehow calculate CYA loss (through splash out, or whatever). And in the absence of that, dealing with the dreadful CYA test! Once they get the new Model Aquatic Health Code pushed through, can we put some effort into a more accurate test?

I thought I knew my CYA, based on water volume. The OP thinks she knows her CYA, based on testing. I'm all but certain my CYA is low (based on testing and chlorine consumption), and the OP has yet to determine what caused her FC to plummet, creating her water issues. I thought maybe it's her CYA, as in: she doesn't have the sanitation level where it should be, so it succumbed to an extra amount of load. So even though there clearly IS an exact science to FC/CYA, how can we, as pool owners without labs, best make use of the science?

The best I can come up with for myself, and for the OP, is that if your CYA was added right, and its level is testing right, and your FC is testing right, and you're still getting water problems, look to the less obvious for the problem. I've suggested water volume calculation, and CYA testing flaws and organic material entering her water somehow (other than rain, that just can't be it, alone).

Thoughts? Ideas? So all I've got for her: don't trust either the CYA test or your water volume calculations if you're having sanitation issues. Listen to the pool and goose your chlorine until you can find the real problem. If the problem only occurs after a rain, and you can't figure out how the weather event is somehow adding additional organic matter, then goose your chlorine right before a rain until you can.

What else can we offer her?

 

[JoyfulNoise]

To the OP-

How long exactly has this pool been filled? Is the plaster beyond its break-in period (28 days after plaster installation)?

If not, a SLAM is not recommended. You could accidentally bleach and fade your plaster color. This is one reason why the break in period requires focused attention - you really don’t want algae to form at this critical time.

Please update this thread with your latest water test results and where you are at time-wise in your break in period.

 

[rcg]

To the OP-

How long exactly has this pool been filled? Is the plaster beyond its break-in period (28 days after plaster installation)?

If not, a SLAM is not recommended. You could accidentally bleach and fade your plaster color. This is one reason why the break in period requires focused attention - you really don’t want algae to form at this critical time.

Please update this thread with your latest water test results and where you are at time-wise in your break in period.

Hey! Thanks for helping. The pool has been full close to 6 weeks. The included pool service had control over it for the first 4 weeks, but I quickly got it up to speed per TFP standards. The day before the storm hit (Thursday), my levels were:

FC 6.5
CC 0
PH 7.8 ( working on lowering this with MA)
CH 475
TA 70
CYA 45

Since then I lowered the pH and started the SLAM. Let me know if anything looks out of place. Thanks!

 

[kimkats]

Remember you should call your CYA 50 for the proper FC level for the SLAM.

Once you start the SLAM don't bother testing anything else. PH does not test correct when the FC is over 10. The other levels don't really matter during the SLAM.

The more you keep the FC at SLAM level the faster your SLAM will go. I suggest you take a pic looking down at your steps each day so you can see the progress of the SLAM. When you are getting close to the end of the SLAM you will not think it is working but when you see the pics you will see the progress.

Have you found the OCLT yet? Here is a link just in case you have not found it:

Pool School - Perform the Overnight FC Loss Test (OCLT)

You will do this test when the FC is holding on the most part and when you think the water is as clear as it is going to get.

Kim

 

[rcg]

Remember you should call your CYA 50 for the proper FC level for the SLAM.

Once you start the SLAM don't bother testing anything else. PH does not test correct when the FC is over 10. The other levels don't really matter during the SLAM.

The more you keep the FC at SLAM level the faster your SLAM will go. I suggest you take a pic looking down at your steps each day so you can see the progress of the SLAM. When you are getting close to the end of the SLAM you will not think it is working but when you see the pics you will see the progress.

Have you found the OCLT yet? Here is a link just in case you have not found it:

Pool School - Perform the Overnight FC Loss Test (OCLT)

You will do this test when the FC is holding on the most part and when you think the water is as clear as it is going to get.

Kim

Thank you for following up, Kim. Really appreciate it. I reviewed the OCLT info, and will move forward as if my CYA is 50. I'm going to really dive in a run that test a few times for practice once this debacle is all cleared up haha. I'll snap pics daily as well. Thanks to this great community for the help.

Raising my FC from 18 to the target FC of 20 for the rest of the slam... Pool is starting to clear up!

 

[Dirk]

Did you check the expiration dates for each of your reagents?

 

[rcg]

Did you check the expiration dates for each of your reagents?

Mine don't have expiration dates on them, but they are from a newly purchased TF kit.

 

[Dirk]

Hmmm, each of my Taylor K-2006 reagents have expiration dates clearly labeled, along with a lot number. Even the tool box container has a lot number, which could help ferret out bad batches. Maybe the TF-100 doesn't offer those, and has a different way to account for quality control... Oh well, dead end there, troubleshooting-wise...

 

[Nectarologist]

Hi. It's likely that the color change was due to mud splashing into the pool. I watched as my pool turned in color from crystal clear in a matter of 5 minutes during a heavy rain. I had all dirt around the pool at the time and the rain made puddles that splashed muddy water into the pool. I just keep running the filter till it cleared (and tested daily). I cut a tarp up and laid it down over the dirt, problem solved. If you're expecting rain again you can get tarps in Home Depot etc for well under $20. Lovely pool btw.

 

[Dirk]

I, too, first thought it has something to do with her open dirt patch right by her pool. I thought maybe getting through the retaining wall somehow. But yes, splashing, absolutely! Was there any mud on top of the retaining wall? Or mud streaks on the deck anywhere?

--edit!--

Shoot, how many times have I written "she" or "her?" Not sure where I got that. It's Randy? As in "boy" Randy? My bad! Sorry 'bout that!!

 

[rcg]

I, too, first thought it has something to do with her open dirt patch right by her pool. I thought maybe getting through the retaining wall somehow. But yes, splashing, absolutely! Was there any mud on top of the retaining wall? Or mud streaks on the deck anywhere?

--edit!--

Shoot, how many times have I written "she" or "her?" Not sure where I got that. It's Randy? As in "boy" Randy? My bad! Sorry 'bout that!!

Haha Dirk, that's okay! I was going to mention it, but you had so much awesome info to share, I didn't want to interrupt!

As far as the pool goes, yes, there was all kinds of splashing and stuff going on. Plenty of evidence on the deck and wall. The winds got up to 40-50 mph, so junk/water was blowing everywhere. That said, the pool is clearing up quickly! I'm not seeing much matter left behind (algae), so I assume you fellow TFP'ers are correct in your assumption that it got contaminated with organic material during the storm.

Once the sun hits it, I'll see how much more filtering we will need to finish the job. Thanks again for the help.

 

[Dirk]

Dear Sir,

Your situation inspired me to check my CYA again (as I mentioned, I've yet to get it to test where I thought it should be) and to do a better job of keeping my chlorine at or above my target FC. I've decided to trust the test (it's not expired) and add some CYA, which is nerve racking for me because CYA is the only thing I've messed up with since taking over my pool (I can't seem to test it right, and I added it wrong at first, burning a small light patch into my pebble). So now I'm hanging my sock and watching it slowly dissolve in, running my pump, and hoping for the best. I'll know in a few days if that's going to solve my slight chlorine consumption issue. Your situation reminded me that all it takes is for your chlorine to be a little low, and some wind and mud, to send your pool water askew. I think that's why they teach us here that even though there is a FC minimum, you should treat your target as the minimum, and never actually rely on the minimum.

Glad to hear your pool is on the mend, and that you've got a handle on the cause. Unless a TFP expert chimes in otherwise, if it were my pool (and I am doing this with my pool), I'd goose the chlorine level a bit right before bad weather (again, not shock level, but just to get it up to the high end of the target range, and maybe a pinch to grow on)...

All that's left is to landscape that dirt!