Began SLAM and problems when using Calculator

[WhitB08]

Hey all! It seems every summer I end up with some algea at some point. Like many others, here in middle Tennessee it’s been unbearably hot with a heat index well over 100 for days. I noticed yesterday when it was overcast on my tanning ledge you could see foot prints and after kicking around it was apparent I had the beginning of some algae. My CYA was at 50 and my FC was 4 ppm. Every time I have checked I have been within the normal range but I guess at some point it must have dropped. I know my CYA should be kept higher with the correct corresponding FC, but because it seems like every summer I get algae I’m always fearful of having the high CYA even though it’s preferable because I’m worried about slamming. Anyway, I went to Walmart and after testing this morning, I think my CYA is actually closer to 40 and my FC was five ppm because I had preemptively bumped it a little last night. Based off of those numbers, my slam level was 16 and with my pool being a little over 24,000 gallons I needed to add 338 ounces of 10% chlorinating liquid. I measured that out exactly and added it this morning. I turned off my SWG and measured again a half an hour later and my FC is somehow 22 ppm. How could this be?

 

[mknauss]

Make sure the pump was on and you have brushed the entire pool well before testing your FC.

 

[Texas Splash]

measured again a half an hour later and my FC is somehow 22 ppm. How could this be?

Either the chlorine was still mixing with the water throwing the result off a tiny bit, or the algae is already getting consumed by chlorine resulting is the reduction of FC. Either way, it's good you checked to see what is happening. I'd give it another 30 min or so and check again. If it's low, simply bump it up and continue with the SLAM Process. It's good you caught this quickly. It's hot!

 

[WhitB08]

Either the chlorine was still mixing with the water throwing the result off a tiny bit, or the algae is already getting consumed by chlorine resulting is the reduction of FC. Either way, it's good you checked to see what is happening. I'd give it another 30 min or so and check again. If it's low, simply bump it up and continue with the SLAM Process. It's good you caught this quickly. It's hot!

I was using the pool math calculator and I was expecting my FC to be about 16 ppm based off of adding the exact amount of bleach to get it there. I was surprised it was so high. Maybe it hadn’t thoroughly mixed. I’ll try it again in a bit, but I am worried about running out of some of my testing regents before I get through with this. So frustrated with myself! I should just know to keep a nice buffer a little above the recommended FC for my CYA when it’s this hot.

 

[WhitB08]

Either the chlorine was still mixing with the water throwing the result off a tiny bit, or the algae is already getting consumed by chlorine resulting is the reduction of FC. Either way, it's good you checked to see what is happening. I'd give it another 30 min or so and check again. If it's low, simply bump it up and continue with the SLAM Process. It's good you caught this quickly. It's hot!

I didn’t think about it not being mixed fully. I went back and read the pool school article on the process before I started because it’s been so long and I wasn’t clear on how long to wait before I would get accurate results. Hopefully there won’t be a next time, but if so I’ll give it a little bit longer. I did brush the pool this morning and even ran my robotic cleaner before I got started.

 

[Texas Splash]

So frustrated with myself!

Don't beat yourself up over it. The water & pool will be fine. For what it's worth, I'm seeing that one gallon of 10% chlorine is about 4 ppm of FC.

 

[WhitB08]

And of course even though the forecast called for spotty storms for the last week and they all missed me, we got almost 3 inches of rain last night.