14,000 gallon pool, added 3 pouches 73% shock yesterday afternoon around 5 in afternoon to get FC up to 25ppm. Prior to shock, FC was around 2ppm, pH 7.6. Just tested today at noon (~19hrs later) and my FC is back down to 2.5ppm and CC= 0.5ppm. My chlorine generator was off last night by accident, so that didn't help keep chlorine up, and the reason for the shock was an algae bloom in the deep end of the pool which rapidly disappeared pretty much immediately after the shock was added. It's been sunny past couple days and my CYA is pretty much non-existent right now. I purchased enough to get pool up to around 70, but dont want to throw off pH until Sunday evening, so the lack of CYA I supposed could certainly have contributed to this as well. I ran the FC/CC/TC test kit twice, and the basic 5 drop test once. Is this normal? Pool looks great, doesn't smell like chlorine anymore like it did right after shock. First year with new to us pool, so I'm always super diligent about testing before people get it out of concern is when people swim it's not going to hurt their skin. I never had a reason not to trust my test kits, and I used two separate methods so I feel pretty good about it being low. Is this drop of FC unheard of?
Shocked yesterday afternoon, only 2.5ppm FC @ noon today
- Thread starter BaltimoreCaesar
- Start date
- Jun 22, 2014
- 47,979
- Pool Size
- 17888
- Surface
- Fiberglass
- Chlorine
- Salt Water Generator
- SWG Type
- CircuPool RJ-45 Plus
Some things to get you back on track:
1 - You need CYA. Be sure you have a minimum CYA of 30. Start with 30.
2 - You observed algae and it doesn't look like you did an Overnight Chlorine Loss Test. If you didn't do the SLAM Process all the way through to completion (pass all 3 criteria), it was never completed. Use liquid chlorine to maintain the proper SLAM FC level as listed on the FC/CYA Levels. If your CYA is 30, then your FC SLAM level would be 12.
3 - Once you pass all 3 SLAM criteria, then you can turn the SWG back on and increase the CYA to about 60-70 since the season will be coming to an end soon.
1 - You need CYA. Be sure you have a minimum CYA of 30. Start with 30.
2 - You observed algae and it doesn't look like you did an Overnight Chlorine Loss Test. If you didn't do the SLAM Process all the way through to completion (pass all 3 criteria), it was never completed. Use liquid chlorine to maintain the proper SLAM FC level as listed on the FC/CYA Levels. If your CYA is 30, then your FC SLAM level would be 12.
3 - Once you pass all 3 SLAM criteria, then you can turn the SWG back on and increase the CYA to about 60-70 since the season will be coming to an end soon.
Much appreciated. I will do a SLAM Sunday, but I guess what I'm asking about today is can I assume dropping ~23ppm in FC in a 19hr period with pretty much 0 CYA is a possibility? I've never saw that quick of a drop when I SLAM'd before, granted I typically keep around 50-60 CYA
Flying Tivo
TFP Guide
- Jan 24, 2017
- 2,969
- Pool Size
- 7500
- Surface
- Plaster
- Chlorine
- Salt Water Generator
- SWG Type
- Pentair Intellichlor IC-40
FC was consumed by algae and UV light. It will continue to do so if you dont do a proper SLAM Process.
It's a certainty. No matter how many FC you started with, it will be gone in a couple hours. It'll lead to more time below minimum and more algae.
You mentioned testing two ways, what are they ?
SLAM is a process and isn't a one-and-done. Have a good read. SLAM Process. We do things alot differently than the pool stores / industry and it sounds like they've been leading you down a path that doesn't work.
The two methods of testing are the TF-100 FC/CC/TC test with speed stir 870 powder, 871 drops, and 003 drops. I ran that test twice with the same results. Then I did the Basic daily Total Chlorine/pH kit where you fill each side with water up to the line, then do 5 drops in each side. Results seemed to confirm my more accurate 870/871/003 test.
I'll run a SLAM starting Sunday. Just wanted to make sure there wasn't something else as a possibility that was causing FC to appear lower than it actually was. Looks like I'm good to go for swimming today and tomorrow. Much appreciated, everyone.
Ok, GREAT.
The block test is more of a 'do I have any chlorone test'. It may agree with you. It also may just do what it wants instead.
SLAM isn’t a one of dump of chemicals, it’s a continuous keeping of the correct level of chlorine per the FC / CYA chart until you pass all 3 SLAM criteria.
Are you familiar with the TFP way? (Your language makes me think otherwise). I’d suggest reading through the Pool School articles to find out about it. It’s actually pretty easy once you get going and there are plenty of friendly people on here to help out if you have any questions.