My First Slam

[yoshi98bc]

I've had some issues balancing my pool and realized I needed to SLAM because I have 0.4 free chlorine and 4.0 combined chlorine. I have a SWG but my CYA is around 40 after the initial pool opening. I kept my CYA at 40 for the slam even though the SWG pools should be between 60-80. Pool math told me to SLAM at FC 16 so I started few days ago. Initial FC was 18.2, little high, but came down to 9.2 next day so added more chlorine. Thought I had the calculations correct but free chlorine shot up to 26 and came down to 22 this AM. Water is clear with a CC of 0.4.

So I have a few questions.

1.How accurate is the Taylor FAS-DPD at high chlorine levels? The titrating fluid seemed to take on a light orange color after 100 drops of 0871.
2.Does the Taylor FAS-DPD test at 10ml have the same accuracy as at 25ml. I tested both ways and got really different numbers.
3.When doing the OCLT, is it any any FC level or just when the FC is below the SLAM level. For example, my FC started at 26 (well above the 16 slam value) and came to 22. Should I wait until FC is around 16 before I repeat the OCLT?

Thanks for any suggestions

 

[Pool Tool]

Keeping your CYA low during slam is smart. You did turn your SWG off right? Did you adjust the chlorine concentration in PoolMath to the appropriate strength and make sure your pool volume number didn't change?

1.How accurate is the Taylor FAS-DPD at high chlorine levels? The titrating fluid seemed to take on a light orange color after 100 drops of 0871. I will the experts weigh in here, but I have had no noticeable issues with accuracy up to FC of 25.
2.Does the Taylor FAS-DPD test at 10ml have the same accuracy as at 25ml. I tested both ways and got really different numbers. I am assuming, in theory the are the same. Although all the test are only as good as the sample and increasing the sample size should improve test accuracy. It's likely a happy medium of sacrificing accuracy for maintaining reagents. What kind of difference are you seeing?
3.When doing the OCLT, is it any any FC level or just when the FC is below the SLAM level. For example, my FC started at 26 (well above the 16 slam value) and came to 22. Should I wait until FC is around 16 before I repeat the OCLT? I don't think there is a hard and fast rule, but I think it has been said to complete close to Slam levels. FC at higher concentrations will much more effected by sun, etc. Although that is why it is done at night, I would repeat it once FC is near Slam level.

 

[Azgirl71]

Not sure how to answer number 1. I have never seen it turn Orange.

2. I just use the 10ml

3. You cand perform OLCT with FC high.

May I ask, why are you doing a SLAM?

Welcome to TFP!

 

[yoshi98bc]

So the slam is for minimal to no chlorine after having my SWG on 100%. I also have a high combined chlorine indicating an issue.

Thanks for the replies. SWG is off. And when you say cand did you mean can or can't?

 

[Azgirl71]

Ok, I was curious. Sorry for the typo. Yes you can do OLCT at high FC levels

 

[Divin Dave]

Its most likely that the error on pool math you are getting due to a variation in volume of what you think it is, vs. what it actually is.
OR, your measuring cup or jug isnt what they say it is.

Sounds though like you are gettting there with your slam. Clear water and .04 CC, good stuff. Go for the OCLT.

to your questions.
1. The FAS-DPD tests accurately up to 50ppm.
2. Not quite the same accuracy but 10ml is just fine. There is no real reason to use the 25ml sample unless you are super OCD. It just uses up valuable reagent. its the regent being used up to fast is why we recommend using the 10 sample.
3. OCLT can be tested at any FC level. The purpose of OCLT is to eliminate FC loss due being bruned off by the sun. The FC level doesnt effect the rate of burn off at all.

Keep your FC at SLAM level until you pass the OCLT test. (if you're a bit higher than slam level, thats ok.. the key to quick success is to not let it get too much below that, if at all).

Once you pass the OCLT, then let the FC drift down on its own until you get to the recommended level and your SWG can take over.

hope this helps,

I've had some issues balancing my pool and realized I needed to SLAM because I have 0.4 free chlorine and 4.0 combined chlorine. I have a SWG but my CYA is around 40 after the initial pool opening. I kept my CYA at 40 for the slam even though the SWG pools should be between 60-80. Pool math told me to SLAM at FC 16 so I started few days ago. Initial FC was 18.2, little high, but came down to 9.2 next day so added more chlorine. Thought I had the calculations correct but free chlorine shot up to 26 and came down to 22 this AM. Water is clear with a CC of 0.4.

So I have a few questions.

1.How accurate is the Taylor FAS-DPD at high chlorine levels? The titrating fluid seemed to take on a light orange color after 100 drops of 0871.
2.Does the Taylor FAS-DPD test at 10ml have the same accuracy as at 25ml. I tested both ways and got really different numbers.
3.When doing the OCLT, is it any any FC level or just when the FC is below the SLAM level. For example, my FC started at 26 (well above the 16 slam value) and came to 22. Should I wait until FC is around 16 before I repeat the OCLT?

Thanks for any suggestions

 

[yoshi98bc]

So since cya is 40 and slam level is 16 and my FC was 22, I shouldn't add anything unless FC drops below 16. Is that correct? If goes below 16, add more chlorine until the three rules are met?

Thoughts?

Thanks

Its most likely that the error on pool math you are getting due to a variation in volume of what you think it is, vs. what it actually is.
OR, your measuring cup or jug isnt what they say it is.

Sounds though like you are gettting there with your slam. Clear water and .04 CC, good stuff. Go for the OCLT.

to your questions.
1. The FAS-DPD tests accurately up to 50ppm.
2. Not quite the same accuracy but 10ml is just fine. There is no real reason to use the 25ml sample unless you are super OCD. It just uses up valuable reagent. its the regent being used up to fast is why we recommend using the 10 sample.
3. OCLT can be tested at any FC level. The purpose of OCLT is to eliminate FC loss due being bruned off by the sun. The FC level doesnt effect the rate of burn off at all.

Keep your FC at SLAM level until you pass the OCLT test. (if you're a bit higher than slam level, thats ok.. the key to quick success is to not let it get too much below that, if at all).

Once you pass the OCLT, then let the FC drift down on its own until you get to the recommended level and your SWG can take over.

hope this helps,

 

[Azgirl71]

Yes this is correct.

 

[pooldv]

Right on!