Hi, just joined TFP today. I live in Houston and have been struggling with green algae in the pool. Leslie's pool supply wants to sell me ammonium sulfate but I've read that this can do more harm than good in the long run. I like the idea of SLAM but I have one question. Using the calculator for a CYA reading of 50, I get a result of 20. Is this the desired FC shock level or the amount of liquid chlorine in fl oz to add to the pool? I assume it is the desired shock level. Seems VERY high to me. How much liquid chlorine would I need with 13000 galloons pool water to raise the FC level to 20 ppm?
Green Algae
- Thread starter nmmc01
- Start date
- Jun 22, 2014
- 47,854
- Pool Size
- 17888
- Surface
- Fiberglass
- Chlorine
- Salt Water Generator
- SWG Type
- CircuPool RJ-45 Plus
Welcome to TFP! 
You are right to question the store's advice. Yes, by referencing the FC/CYA Levels, the elevated SLAM (FC) level would be 20. Is that something that is dangerous or horrific? ........ No. In a pool store world where everything is a generic "1-3 ppm", it would be odd. But when you apply science and the relationship of FC to CYA, and validate proper ratios for FC at normal daily levels and those required to kill algae (while still safe to swim), it all makes sense.
Do you have a TF-100 or Taylor K-2006C test kit to conduct a SLAM Process? If not, I would encourage it. I have a TF-100 (link in my signature) and will never look back. You won't either.
Be sure to visit our Pool Care Basics and let us know if you have ANY questions at all. We're happy to help.
You are right to question the store's advice. Yes, by referencing the FC/CYA Levels, the elevated SLAM (FC) level would be 20. Is that something that is dangerous or horrific? ........ No. In a pool store world where everything is a generic "1-3 ppm", it would be odd. But when you apply science and the relationship of FC to CYA, and validate proper ratios for FC at normal daily levels and those required to kill algae (while still safe to swim), it all makes sense.Do you have a TF-100 or Taylor K-2006C test kit to conduct a SLAM Process? If not, I would encourage it. I have a TF-100 (link in my signature) and will never look back. You won't either.
Be sure to visit our Pool Care Basics and let us know if you have ANY questions at all. We're happy to help.
Thank you Texas Splash. I do have the appropriate test kits to conduct a SLAM. I put in 333 fl oz of liquid chlorine yesterday evening and ran the pump overnight. The 333 fl oz is the recommended amount based on size of pool (13000 gallons) and 10% chlorine. I use 128 fl oz jugs. I set the pool ph to 7.2 beforehand. This morning I measured the FC and it was 10. Since my target is 20 either I didn't add enough chlorine or 10ppm of FC were consumed overnight by algae. I guess I need to add more chlorine to bring the levels up to 20 ppm. Am I right in my logic?
Oly
Gold Supporter
Yes you are correct, maintaining your SLAM FC level is key. Also test 30 minutes after adding liquid chlorine to verify you are at or slightly above your SLAM target. Expect significant FC loss during the beginning. As you progress the loss will slow but maintain your FC level. Reread the procedures..... SLAM Process
- Jul 17, 2019
- 3,714
- Pool Size
- 13000
- Surface
- Plaster
- Chlorine
- Salt Water Generator
- SWG Type
- Pentair Intellichlor IC-40
Sounds like you are on the right path. The more often you test and add chlorine the better and quicker you will see results. We often see people only test/add chlorine 1-2 times a day which prolongues the SLAM and increases the frustration for all.
Also make sure you read the SLAM article a couple of times and follow the advice there on brushing, backwashing and the 3 tests to let you end the SLAM.
Also make sure you read the SLAM article a couple of times and follow the advice there on brushing, backwashing and the 3 tests to let you end the SLAM.