Can’t get FC numbers up

[JDOKC]

Hello all - so thankful I found this community because my local pool store advice is definitely not cutting it.

I’m having algae issues, and I attempted to address using SLAM, but I can’t seem to get my FC numbers up. My CYA is at 30, I added a gallon of 12.5% bleach at night, and when I tested in the morning my FC was maybe 0.5. Where am I going wrong? Based on my calculations that gallon should have been more than enough.

6K gal, AG vinyl, 1.5 HP Hayward pump, doughboy sand filter, DPD Test Kit

 

[PoolStored]

Hello all - so thankful I found this community because my local pool store advice is definitely not cutting it.

I’m having algae issues, and I attempted to address using SLAM, but I can’t seem to get my FC numbers up. My CYA is at 30, I added a gallon of 12.5% bleach at night, and when I tested in the morning my FC was maybe 0.5. Where am I going wrong? Based on my calculations that gallon should have been more than enough.

6K gal, AG vinyl, 1.5 HP Hayward pump, doughboy sand filter, DPD Test Kit

Hey, Welcome To TFP!! I was pool stored, that's why I am PoolStored!

With SLAM it is a process, not a one time event. You test your FC and raise it to your target FC for a SLAM. You test and re-add liquid chlorine every 1-2 hours until 1) your overnight FC loss is <= 1, 2) your CC <=.5 and 3) your pool is clear.

Your SLAM target, for CYA of 30 is 12 FC. That can be found at this link: FC/CYA Levels

Take a gander at the SLAM process. Print it out, that helped me. It can be found at this link: SLAM Process

No question is a bad question, we can get you looking like this -->How Clear is TFP Clear?

 

[Texas Splash]

Welcome to TFP! Along with the advice above from PS, your signature shows only a DPD test kit. That could be a limiting factor as well. If you don't have a TF-100 (link in my signature) or Taylor K-2006C test kit, I would definitely make that a priority. It helps tremendously. Good luck with your SLAM Process.

 

[jeffchap]

One gallon of 12.5% bleach in a 6k gallon pool should have raised your FC by 21 ppm. That's way high. It's unlikely your pool used that much chlorine overnight unless it is an absolute swamp. How does your water look?

So I have to wonder about your testing. You state that you have a DPD test. But AFAIK those can only test FC up to 10 ppm. You need a FAS-DPD test from one of our recommended test kits to test for FC > 10. See Test Kits Compared. If all you are lacking is the FAS test, you can get that by itself for around $35.

The other possibility is that your chlorine was old and weak. Is there a date on the bottle?

If you truly believe your FC is only 0.5, use PoolMath to determine how much chlorine to add to achieve 5 ppm per day.