you could potentially add up to 5 lbs of trichlor tabs in total to bring CYA to 32 ppm This would give you total FC raise by 52 ppm but the problem is it would also drive your pH down by 2.8 meaning you'd also need to add 30 lb of soda ash to restore pH back. The last number is very approximate as we don't know your current water TA. Bottom line- don't get carried away with those tabs, prob better if you add CYA separately and bring FC up with bleach to avoid side effects. Tabs use require some experience and good test kit handy.
New to the site and checking my knowledge
- Thread starter phillijp
- Start date
you could potentially add up to 5 lbs of trichlor tabs in total to bring CYA to 32 ppm This would give you total FC raise by 52 ppm but the problem is it would also drive your pH down by 2.8 meaning you'd also need to add 30 lb of soda ash to restore pH back. The last number is very approximate as we don't know your current water TA. Bottom line- don't get carried away with those tabs, prob better if you add CYA separately and bring FC up with bleach to avoid side effects. Tabs use require some experience and good test kit handy.
Please do not add any more CYA until you get a valid CYA test. "Guessing" is not what we teach.
Even if we could say the CYA of 190ppm was valid, if the OP drained exactly 85% of their water that would still leave about 30ppm of CYA. Adding another 30ppm on top of that, plus using tabs (just five 8oz tablets will add another 16ppm of CYA) and the OP could be up to 80ppm CYA in no time.
In a 10,350 gallon pool, 16oz of 8.25% chlorine will raise FC by 1ppm (or 13oz of 10%, or 11oz of 12.5%). Add 4-5ppm of chlorine a day until your test kit arrives.
Dom
- Jan 4, 2016
- 5,288
- Pool Size
- 44000
- Surface
- Plaster
- Chlorine
- Salt Water Generator
I agree with Dom, hold tight and just add liquid chlorine. I would put the pucks/tabs away somewhere until you have reliable numbers. They keep fine and are handy for vacations.
You had some fairly obvious chloramine smell which suggests there's a high chance you will be doing a SLAM, which will be easier with CYA down at 30ish.
You had some fairly obvious chloramine smell which suggests there's a high chance you will be doing a SLAM, which will be easier with CYA down at 30ish.
My bad, didn't realize that small portion of leftover water might already have enough CYA. Please use bleach only as recommended.
Results are in. I ran the test twice because I assumed a learning curve and wanted to verify my results. Except for CC my results were very close both times and I attribute the CC inaccuracy to overzealous squeezing. I'll list both results but according to Pool Math, I'm good and already starting my SLAM even if unintentional (time to dial back the liquidator). Thoughts?
FC: 20 20
CC: 2.0 0.5
PH: 7.6 7.7
TA 120 110
CH 13 11
CYA 54 52
CSI: -1.08
FC: 20 20
CC: 2.0 0.5
PH: 7.6 7.7
TA 120 110
CH 13 11
CYA 54 52
CSI: -1.08
How are you getting those CH & CYA numbers? The CH test is 1 drop = 10ppm, and the CYA test is graduated by 10's.
Did you perhaps count the CH as 1 drop = 1ppm? That would make your CH 130 & 110 ppm.
If you are reading the CYA a "bit over" or "halfway between", the CYA scale does not work that way as it is not linear. We round up to the next 10, so "halfway between" 50 & 60 would be rounded up to 60ppm.
At a CYA of 60ppm, your shock FC for the SLAM is 24ppm.
Dom
OK so I forgot to multiply CH by 10, after correcting the math error the values make more sense, thanks. And thanks for heads up on reading CYA, it looks like mother nature is about to do drown us so I'm sure these numbers are short lived.
So if I've digested the information correctly I should do an OCLT next to see where CC is and go from there. Acceptable range is 0-0.5?
If it is an overcast day your CYA value will be incorrect. CYA needs to be checked outside on a bright sunny day, with your back to the sun, view tube at about waist level and about 6 inches away from your body. The idea is to keep the tube in your shadow, but allow as much indirect light as possible illuminate the particles in the solution.
The OCLT will tell you if something other than sunlight is consuming your FC. You already posted a CC value but you should do it again as there was a big difference between results. CC's should be 0.5ppm or less. A 'clean' pool will usually be at 0ppm. I occasionally get CC of 0.5ppm if I check right after a big swim party (sweat etc being oxidized), but otherwise I am at zero CC's.
If your pool is completely clear of any algae, your CC's are 0.5ppm or less, and you pass the OCLT you have no reason to SLAM.
http://www.troublefreepool.com/content/136-perform-the-overnight-fc-chlorine-loss-test-oclt
http://www.troublefreepool.com/content/125-slam-shock-level-and-maintain-shockingl
Dom
Ok, copy the information on accurate cya interpretation, today is cloudy so I'll wait till we get a sunny day.
I was going to do another chlorine test tonight as per OCLT, I'll post the results in the morning.
Is 20ppm ok to swim in?
Thanks for all the help so far.
A FC of 20ppm is OK to swim in if your CYA is 50ppm. (it's fine to swim in FC up to your shock level for your actual CYA level)
If your CYA is a bit lower than 50ppm the FC may be irritating to those who are sensitive to it, and may slightly bleach out your swimwear.
Dom
If your CYA is a bit lower than 50ppm the FC may be irritating to those who are sensitive to it, and may slightly bleach out your swimwear.
Dom
- Jan 4, 2016
- 5,288
- Pool Size
- 44000
- Surface
- Plaster
- Chlorine
- Salt Water Generator
You're moving well along with taking control of your pool!
Our safe swimming rules are:
- water clear to the bottom so you can always see swimmers
- pH between 7.2 and 7.8
- FC at or above minimum and at or below shock level for your CYA level per: Pool School - Chlorine / CYA Chart
So 20 ppm FC would be fine if you were confident the CYA is 50 or greater.
That was a good idea doing your tests twice as you work through all this and gain confidence.
Our safe swimming rules are:
- water clear to the bottom so you can always see swimmers
- pH between 7.2 and 7.8
- FC at or above minimum and at or below shock level for your CYA level per: Pool School - Chlorine / CYA Chart
So 20 ppm FC would be fine if you were confident the CYA is 50 or greater.
That was a good idea doing your tests twice as you work through all this and gain confidence.
Well no OCLT tonight, FC dropped to 18 when I checked it at sunset. I left the pump on so hopefully it'll be ready tomorrow night.
I read somewhere (it's not in the official OCLT procedure) that I should leave the pump on and scrub the walls and floor, Yes? Maybe that was for the SLAM.
I read somewhere (it's not in the official OCLT procedure) that I should leave the pump on and scrub the walls and floor, Yes? Maybe that was for the SLAM.
- May 16, 2011
- 1,180
- Pool Size
- 28000
- Surface
- Plaster
- SWG Type
- Pentair Intellichlor IC-60
When was the last time you had checked the FC before sunset? As far as I understand, it is reasonable to lose 2 ppm at SLAM levels if it was over a span of time when the sun was still up. In that case, it could be attributed to UV rays and not necessarily algae. So you might still be able to do an OCLT tonight if you wanted to try.
Yes, that is correct. Test after the sun is off the pool and see how it looks in the am.
Please don't place them in the skimmer. The concentrated high acidity can deteriorate your skimmer, pipes, equipment, etc. If you are going to use pucks, please place them at the returns -- use old socks, etc.
The first FC test was at noon, it was overcast today and mother nature deposited an inch of rain around 4pm. I bailed on the OCLT because I wanted to roll right into a SLAM and according to the CYA/Chlorine chart I was slightly under to ideal FC number. I work third shift so I had to leave for work at 8pm so as the saying goes "tomorrow is a new day". I left the pump on so FC should be good to go for an OCLT tonight. When I get home in 2 hours I will do the test again to see where the levels are (I'm still trying to dial in the liquidator as well).
- Jan 4, 2016
- 5,288
- Pool Size
- 44000
- Surface
- Plaster
- Chlorine
- Salt Water Generator
You can do the OCLT at any FC level from 3 ppm FC and up. It doesn't have to be at SLAM level for the OCLT to be valid. Here's the procedure, which needs to be followed carefully: Pool School - Perform the Overnight FC Loss Test (OCLT)
The CC test is not part of an OCLT.
The CC test is used to help you know if you need to SLAM or continue SLAMing
The CC test is not part of an OCLT.
The CC test is used to help you know if you need to SLAM or continue SLAMing
Well it's another cloudy day. It's been clear and hot for the last two weeks but now that I *need* a clear day Mother Nature is messing with me.
Had a few minutes of sunlight this afternoon, CYA is a solid 60, FC was 28 CC was .5. I'll start the OCLT in a few minutes.