Unusual test results

outbacktommy

Well-known member
May 11, 2017
55
Elk River, MN
The background:
For reasons that have not yet been determined, the output of my SWG failed and the FC went to 0 sometime during the week. The obvious surprise consequence was a cloudy pool the following weekend, so I hit the turbo boost on the cell and tossed in about a pound of dichlor that's been sitting in the shed for about 3 years just to get the whole thing kick started again- very unscientific guess. My CYA last year was about 40 and I don't have any reason to believe that it changed (maybe dropped a little), so I didn't replace the testing reagents when they ran out- I wasn't too worried about the dichlor adding a bit more CYA.

The problem is that now when I tried to test for FC, I get .4 but if I wait a minute, the sample turns pink again on it's own. I added another drop or two and it went clear, but a minute later it was pink again. This continued until I gave up w/ FC at 2.0. The expiration dates on my reagents are all June 2019 and they were stored carefully. With these unclear results, I don't really trust what my FC and CC levels are. Why is this happening? Is it the old Dichlor?
 

mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
23,062
Laughlin, NV
Once the FC test goes clear, the test is over. Your FC is 0.4.

You have algae and you do not know what your CYA level is. I suspect your SWCG may be fine. It just could not keep up with the algae bloom.

You need to get the R0013 and test your CYA. I suspect it is not nearly as high as you think. CYA degrades over time and I would think you drained some water for winter and that was replaced with fresh water.
 

JoyfulNoise

TFP Expert
Platinum Supporter
May 23, 2015
16,133
Tucson, AZ
The FC/CC testing needs to be completed in under a minute or so. As soon as the first transition from pink to clear happens that is FC. Then you add the 5 drops of R-0003 and titrating immediately to get CCs. There are technical reasons for why this is that I won’t get into except to say that the dye is very sensitive to oxidizers and will revert back from clear to pink very quickly. So speed is of the essence for that test. If you don’t have one, get a SpeedStir. It makes testing much quicker and easier.

You likely have very high CCs which is why your seeing the rapid breakthrough at the end of the FC test.

There is nothing wrong with your reagents. It’s your testing methodology that needs improvement.
 

outbacktommy

Well-known member
May 11, 2017
55
Elk River, MN
I did not know that cya degraded over time. Other posts said that the only way to get rid of it was to drain and refill. I have an autocover, so I don't drain at all over winter so the cover doesn't rip out from the snow load. (per the builder's recommendation). I did need to add about 3" of water this spring though- not unusual.

Ok, so, my FC is 1.0 this morning, CC is 4.0 and the water is still cloudy. What is the recommended course of action? Will a 3rd turbo-boost on the SWG help? Will it help to open it up to sunlight for the day? I still have about 2-3 more pounds of dichlor (3-yr old pail of granules)- can I use this up? How much? I've never had an issue like this before (3 years of ownership), the SWG has always been the greatest trouble-free device in seasons past.

As for CYA, I'm getting more reagent and will have an update later in the week.
 

mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
23,062
Laughlin, NV
No. A CC of 4 means this pool has real issues or you are not opening it enough to let the CC burn off.

Open the pool for an entire day and let the sun shine on it. Then test CC. If still high, there could be a situation that a drain and refill would be best.
 

outbacktommy

Well-known member
May 11, 2017
55
Elk River, MN
A drain and refill is not my preferred option due to the high calcium hardness of our local water. I spent a lot of effort getting CH down to it's current level (using softened water last season) and I don't want to repeat that anytime soon. The water looks a little better after an afternoon in the sun- only about 6 hours of hazy skies, but the CC only went down a to 3.8 and FC is still 1.0 My first instinct is to go for another day in the sun before making the next decision, then as much sun as I can give it for maintenance. I can make out the patterns on the bottom of the pool (5') ok and there is no color to the murkiness. Your thoughts?

Are slam or shock viable options?
 

Donldson

TFP Expert
LifeTime Supporter
In The Industry
Jun 12, 2009
3,958
NW Ohio
You need to know your CYA level to implement the SLAM Process, so until you get your new reagents in your best bet is to use liquid chlorine to dose your FC up to 10. Retest every few hours when possible, bringing it back to 10. When your R-0013 arrives do a CYA test and bring it to 30 if it is lower than that, then follow the SLAM Process exactly until your CC is 0.5 or lower and you pass an OCLT. Once you complete the SLAM you can bring your CYA up to operational level and things should be running smoothly.
 

outbacktommy

Well-known member
May 11, 2017
55
Elk River, MN
Added bleach last night based on an estimated CYA of 30 and target FC of 10. Test showed FC of .6 and CC of 4+ before adding bleach.
This morning, FC was 3.8 and CC was .4 so I'm happy that the response was rapid. Since it was so fast and CC still exists, I added more bleach raise to a calculated FC of 10 again. We shall see what it looks like when I get home from work but I am optimistic that I'm done. Thanks all for the advice.
 

outbacktommy

Well-known member
May 11, 2017
55
Elk River, MN
6pm after work: FC=0.4, CC=0.6, pH dropped from 7.6 to 7.2. Temp=86. Added another 6 quarts of 12.5% bleach (PoolMath) to target 10-12 FC. Put the robot in the pool to pick up debris and stir the crud on the bottom- yeah, I know they say not to abuse the robot like that, but it was too hot outside to do any actual work.

10pm: FC=2.4, CC=0.2, did not test pH. added another 5 quarts of 12.5% bleach (PoolMath again) to target 10-12 FC. Pulled the robot. Pool looks a little better every time I check on it, but still a bit cloudy and something is still gobbling up the FC really fast. Increased the SWG from 12% to 90% to try to keep the FC up overnight.
 

outbacktommy

Well-known member
May 11, 2017
55
Elk River, MN
48 hours since first bleach addition. Note that yesterday's pH test was done when FC was 0.4. It was just out of curiosity, I know it didn't really mean anything.
Today, 6:30a, FC=2.4, CC=0.4, Temp=85, SWG still at 90% to reduce need for bleach (theoretically). Added another 5 quarts of 12.5% bleach (PoolMath) to target 10-12 FC.
After work- 5:30p: FC=2.5, CC=0.5, Temp=86, SWG still at 90%. Added another 5 quarts of 12.5% bleach to target 10-12 FC. Pool is nearly clear but FC is still disappearing.
Having never needed to Slam in 3 seasons (since starting TFP) I'm amazed at how much bleach and how long this takes. It would probably go faster if I knew my CYA (still assuming about 30) or if I could sneak home mid-day to top up the FC. I'm expecting the new reagent to arrive today, but it's still not here. My pool store doesn't put a lot of stock in testing for CYA except for test strips which I really don't trust.
 

cfherrman

TFP Guide
May 10, 2017
2,412
Hays, Kansas
Yeah just wait for the reagent. You are doing good.

It's a guess but I think your cya is lower than 30

If your cya test doesn't show anything, assume 20 cya when adding cya so you don't add too much.
 

IceShadow

Gold Supporter
Jun 8, 2019
1,072
Milwaukee, WI
Can you test more often when at home and bring FC up more often? Once an hour if possible? That will get you through the SLAM faster. As mentioned, use 10ml samples and one scoop of powder to save reagents. One drop = 0.5ppm of FC / CC.
 

outbacktommy

Well-known member
May 11, 2017
55
Elk River, MN
11pm. CYA reagents did not arrive today :( but FC=5.5, CC=0.5, everything else is the same, so it is definitely slowing down. Optimistic with a very hot weekend starting tomorrow ;) Added 3qt 12.5% bleach to target FC=11 for overnight. And yes, I started using the 10ml samples- thanks for reminding me.

Very curious where the chlorine is going- and where the sodium is going? Other chem threads say that it doesn't 'gas' off as is commonly claimed but converts to other things in a long and complicated chain of organic reactions. But really- where does the chlorine and sodium go- does it just give its oxygen to the algae to 'burn' up the organic hydrocarbons then wind up as simple NaCl salt? Why isn't my CC going up?