pH, FC, CYA, green water

kschmidt1

LifeTime Supporter
Aug 2, 2015
173
Grandy, NC
Did sloppy job non-closing NC above ground last fall. Peeked under cover and oops! Brownish green. I know what I did wrong, need a little guidance on clean up. Didn't think about all details except need chlorine. Had two gallons of 10% from last fall and dumped them in 19300 gal. Added 2 more gallons 10% chlorine this morning. Got out test kit, first test FC 11, dumped Acid ...into pool for Ph! 3 hrs later, tested FC 9, pH 7.5 and CYA haven't done anything yet. Should I dump a 1/2 gal liquid stabilizer and in a few hours drop more chlorine and wait until morning to do testing. The green/brown has lightened enough for me to see, albiet barely, leaf pile in center (water 52, will use rake tomorrow):confused:. Not sure what slam FC number to use since no CYA, just knew get the chlorine in. Thanks for deciphering this and any advice welcome.
FC - 9
CC - .5 (barely)
pH - 8+++ (flourescent pink)1
CYA less than 25 (prob none)
 

mguzzy

Gold Supporter
I would get some CYA in there to protect all the chlorine you are going to be SLAMing with.. just get it to the lowest for a SLAM on the FC/CYA Chart.. and SLAM away... don't forget to get those leaves out.. no sense wasting all your chlorine on the decomposing leaves, instead of the live algae.

Nextime, dump the chlorine in front of a return jet.. it dilutes it out better
 
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Mdragger88

Bronze Supporter
Jun 1, 2018
1,958
Hernando, Ms
Pool Size
26000
Surface
Vinyl
Chlorine
Salt Water Generator
SWG Type
Intex Krystal Clear
The 1/2 gal of liquid stabilizer should raise your cya by about 10ppm. Also Adjust ph to 7.2 before going above 10 ppm fc & just follow the SLAM Process - the more u test & dose the faster it will go. Re check the cya in about 24 hrs & then adjust fc level as necessary.
 

kschmidt1

LifeTime Supporter
Aug 2, 2015
173
Grandy, NC
I would get some CYA in there to protect all the chlorine you are going to be SLAMing with.. just get it to the lowest for a SLAM on the FC/CYA Chart.. and SLAM away... don't forget to get those leaves out.. no sense wasting all your chlorine on the decomposing leaves, instead of the live algae.

Nextime, dump the chlorine in front of a return jet.. it dilutes it out better
Thanks.
 

kschmidt1

LifeTime Supporter
Aug 2, 2015
173
Grandy, NC
OK...added stabiizer last nite. Yeah! Reading 30 this AM
FC last nite was 9, this AM still at 9. (SLAM level should be 4-6)
CC-0 this morning
pH down to 7.5 after adding acid. No change in pH this AM.
Pool cloudy blueish tinge to.
Is cold water affecting numbers? Don't understand no changes in FC.
Going to try to see leaves to get them out this AM. Anything else? THANX!
 

JJ_Tex

Gold Supporter
Bronze Supporter
Jul 17, 2019
2,323
Prosper, TX (DFW)
Pool Size
13000
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-40
OK...added stabiizer last nite. Yeah! Reading 30 this AM
FC last nite was 9, this AM still at 9. (SLAM level should be 4-6)
FYI, FC 4-6 is the normal range for CYA of 30. The SLAM level is 12.
 
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wireform

Silver Supporter
In The Industry
Aug 15, 2017
2,115
Spring Valley, NY
Slam for 30 CYA is actually 12. You need to absolutely rid the water of any organics. That'll consume all the chlorine really fast thus not working the water quality.
 
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CrystalRiver

Well-known member
Jun 19, 2020
542
Massachusetts
Cold water greatly affects the CYA test. Grab a sample, take it in the house and let it warm up to 70ish before you begin.

What's done is done, but liquid CYA is a crapshoot how much you actually get, unless you dump (and rinse) the whole jug. It's not dissolved well in the jug at all, it tends to sit in the bottom, so the top half is much more dilute than you expect and the bottom half is much, much more concentrated.

Given those two factors, retesting your CYA with warm sample water is in order. Then test and adjust your pH to 7.2 before adding chlorine to raise to SLAM levels. Then ignore pH until SLAM is over, as the pH test is unreliable at FC over 10ish.

Getting those leaves out will be huge. Even if the water is too murky to see, scoop blindly, any progress on those leaves is better than none. You'll never win the battle until they're out. Ask me how I know.
 

kschmidt1

LifeTime Supporter
Aug 2, 2015
173
Grandy, NC
Cold water greatly affects the CYA test. Grab a sample, take it in the house and let it warm up to 70ish before you begin.

What's done is done, but liquid CYA is a crapshoot how much you actually get, unless you dump (and rinse) the whole jug. It's not dissolved well in the jug at all, it tends to sit in the bottom, so the top half is much more dilute than you expect and the bottom half is much, much more concentrated.

Given those two factors, retesting your CYA with warm sample water is in order. Then test and adjust your pH to 7.2 before adding chlorine to raise to SLAM levels. Then ignore pH until SLAM is over, as the pH test is unreliable at FC over 10ish.

Getting those leaves out will be huge. Even if the water is too murky to see, scoop blindly, any progress on those leaves is better than none. You'll never win the battle until they're out. Ask me how I know.
Thanks for the info. I did work hard to get solidified CYA out of jug. Next AM read CYA 30.

Talk a out bad luck being my only luck...vacuumed as much as I thought might be good and was about to lower pH (I use Muratic Acid from the paint aisle) (somehow ramped to over 8) and decided to backwash first. Finished backwash went to turn on pump for acid and pump quit.

Next day, in middle of 'slam' was able to find a replacement, overnight it (of course was on UPS truck until 6PM, but neighbors and I worked to get going.

Let it run few hours tested, pH had dropped to 7.2 FC still cloudy, FC-12, CC-0, tried to do CYA on a cloudy day with cold water. Came up with 50. Wasn't sure was going to be sunny today for another test, was searching for alternative method and found your post. I just came in from getting a sample and putting some aside to warm up for another test. Surmised if it's still cloudy, the CYA must be higher and have not been putting in enough FC. Wonder if I could put sample water into microwave to speed up this process...Thanks again.
 

kschmidt1

LifeTime Supporter
Aug 2, 2015
173
Grandy, NC
One more time, got my CYA figured out at 40. SLAM level at 16. Leaves gone, pump working, why is it so slow to clear? Is the cold water impeding chlorine?
 

wireform

Silver Supporter
In The Industry
Aug 15, 2017
2,115
Spring Valley, NY
One more time, got my CYA figured out at 40. SLAM level at 16. Leaves gone, pump working, why is it so slow to clear? Is the cold water impeding chlorine?
Pool needs to be brushed if possible twice daily and slam needs to be kept up there without dropping very much if at all possible. The more it drops between your target slam the longer it can take. That's not to say if you maintain slam that it won't take its time. Make sure your sand filter isn't retaining too much algae and therefore may need several backwash cycles while the slam is working it's way through.
 
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CrystalRiver

Well-known member
Jun 19, 2020
542
Massachusetts
Yes, cold water makes it take longer. Algae grows much slower in cold temps, which slows all cellular processes. The algae are slower to take in chlorine, which makes it easier to maintain your FC levels, and the algae grow slower if your FC drops. But at the same time, the algae are slower to die because it's slower to take in that FC. It's kind of good and bad all at the same time.
 

kschmidt1

LifeTime Supporter
Aug 2, 2015
173
Grandy, NC
Yes, cold water makes it take longer. Algae grows much slower in cold temps, which slows all cellular processes. The algae are slower to take in chlorine, which makes it easier to maintain your FC levels, and the algae grow slower if your FC drops. But at the same time, the algae are slower to die because it's slower to take in that FC. It's kind of good and bad all at the same time.
So, when I look at a blue, slightly cloudy pool, which is not giving up any green in a backwash, and only end up using 2ppm chlorine a day, it's taking it's good old time.o_O Doing 16ppm for SLAM FC. Have been doing 10ml testing, could I do 5ml to try to save reagents? Thanks for answering about cold water. I have done SLAM procedure before, but never with cold water, especially since CC=0 the whole time. Will carry on. THANKS(y):giggle:
 

mguzzy

Gold Supporter
If it is just slightly cloudy sounds like you are in the final SLAM stages.. and just filtering out the dead algae. When was the last time you deep cleaned your Sand Filter. That might help with filtration in the last stage.
 
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kschmidt1

LifeTime Supporter
Aug 2, 2015
173
Grandy, NC
If it is just slightly cloudy sounds like you are in the final SLAM stages.. and just filtering out the dead algae. When was the last time you deep cleaned your Sand Filter. That might help with filtration in the last stage.
Thanks.
 

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