SLAM Clarification

Jump to latest Follow Reply
4

440dodge440

0
LifeTime Supporter
Apr 7, 2015
315
South Central PA
Hi,
I got my pH at 7.5 and CYA 35, so I'm going to start SLAM. Never having done this before, I plan on adding 3 jugs of bleach (FC=1 to FC=14) and re-checking an hour later. I will be doing this after work, so I have about 4 hours until dark....My question is, how much do I have to stay on top of any chlorine dissapation? If I'm constantly adding bleach to maintain the shock level, do I have to keep doing it into the night, or will the effectiveness of what I did remain until the next day....I'm really trying to understand how important the timing is. The pool water is very clear, but I have very little FC (the water barely turns pink when adding the FAS/DPD powder)

Thanks

20000 gal
Vinyl Liner
DE Filter
 
Good questions, easy answers.

You stay on the dosing and retesting as often as you possibly can. Every couple of hours at first. You don't have to stay up all night, but first thing next morning, check it. To find out if the doses hold, you'll have to determine that from testing. The goal, is to never let the FC drop below SLAM value for your Cya. Get as close to that as possible. When you dose, be careful to choose the right amount, but shoot for a few PPM higher than target. Say 24 IF your target is 20. That will give you a tiny extra, and at first, it may be consumed rapidly.
 
To add, don't get caught in the trap some fall into - if just a little more chlorine helps, a lot will be great. Nope, it doesn't work that way Just overshoot a little. Too much may damage equipment or fade your liner.

You also said "I have about 4 hours until dark". You can continue the SLAM after dark, in the rain any time at all. Don't just stop because it gets dark. After dark you no longer have any loss to the Suns UV rays, so every drop you put in after dark is working on the algae. So during the evening at the end of each TV show go out and test the water and adjust the FC back up......
 
And... if your schedule allows, keep dosing and testing after dark. No sun means no chlorine is lost to sunlight! Don't lose any sleep over it pulling an all-nighter or anything though. Ideally, you'd be testing/dosing every hour until the SLAM is complete, but we've all got lives and the SLAM will progress as long as your testing and dosing several times per day and keeping the FC near SLAM level. It's OK to go 1-2 FC over the recommended SLAM target if you're not going to be able to dose for a longer period (sleep, work, etc.).

When you get a chance, add the details of your pool to your forum signature. That way they're always there so that folks can more easily help you out. To change your profile and/or signature, select "Settings" (top right under Pool School button). Scroll down (left side) to "My Settings" & select Edit Profile or Edit Signature.
 
That "light pink" syndrome can occur when the water is still a bit chilly too. Take a sample inside, let it warm and see if you have a difference. WHY are you slamming?
 
Thanks for all the input. The reason I'm slamming is that I want to transition from the tablets to liquid chlorine, and my FC is extremely low....is SLAMMING in this case not appropriate? I'm learning more and more as I go alone, but previously I added liquid chlorine a few gallons at a time (probably a total of 5 gallons to this point), not actually following SLAM as it turns out, but it did very little to FC, ant the auto chlorinator is doing very little as well. Should I be SLAMMING?
 
440dodge440 said:
Thanks for all the input. The reason I'm slamming is that I want to transition from the tablets to liquid chlorine, and my FC is extremely low....is SLAMMING in this case not appropriate? I'm learning more and more as I go alone, but previously I added liquid chlorine a few gallons at a time (probably a total of 5 gallons to this point), not actually following SLAM as it turns out, but it did very little to FC, ant the auto chlorinator is doing very little as well. Should I be SLAMMING?
Click to expand...
Unless you have something growing in the water (visable algae, cloudy water, fail OCLT) there is no need to SLAM. Just stop using pucks and use liquid each day.

Are there still tabs in your feeder?

Can you give us a full set of test results?

Have you conducted an Overnight FC Loss Test (OCLT)?

Sorry, lots of questions but we want to direct you down the right path.

How much Pool School have you read? Start with these:
ABCs of Water Chemistry
Recommended Pool Chemicals
How to Chlorinate Your Pool
 
If the water looks good, testing shows less than .5 CC and you can pass the OCLT then you have no need to spend the money on extra bleach to SLAM. Just start using bleach to reach the proper FC level for your CYA and maintain. ;)
 
Seems to me than an overnight chlorine loss test is in order here (OCLT). If you're good there---your water is already clear and you have no visible signs of algae---no reason to SLAM just to "convert". FULL test results please!
 
I apologize if I'm not understanding well, but this is my first year with a pool, so I'm not real clear on all of the tests....I read about the OCLT, and I did the FAS/DPD test (though not comparing overnight), and the test shows about 1 ppm of FC...the OCLT requires no more than 1ppm loss of FC, correct? So if I'm starting with (barely) 1ppm, I'm not really going to know if I pass or fail. I guess I thought SLAM would bring my FC level up to a point where I could detect a difference in the OCLT. It would be great if I don't need to SLAM, but how do I bring the FC level up -should I use pool math and add liquid chlorine to go from FC=1 to FC=4.5 (target in my case), and keep adding to try to maintain that? I will do another CC test- I did one the other night, and I got between .5 and 1 (depending on when I actaully determined when the water cleared), but it was the first one I did and I was unclear on what I was actually testing- I was just following instructions....
 

Enjoying this content?

Support TFP with a donation.

Give Support
Typically the OCLT is performed at higher (SLAM) levels. In your case, I would use Pool Math to try to bring FC up to 6 or a bit more. Once you've added bleach, let circulate for and hour then retest to get your starting point for the OCLT. Test FC in the morning. It's best to do your pre-OCLT after sundown and your morning test before/close to sun up.
 
How often are you adding chlorine? With a CYA of 40 you should never let your FC drop below 3. To keep it above 3 we generally target 5 so that as the sun consumes it during the day it does not go below 3.

As to your CYA, the scale on the tube is not linear, so you can't say half way between 30 & 40 is 35, just assume 40 for chlorine additons.
 
I had the auto chlorintor with tablets on full until a few days ago- I was concerned about getting the CYA too high, so I turned it down to 1/4, and will close it when I get this liquid bleach thing figured out (prior to OCLT). This is all that's adding chloring at this point. The pool was just opened for the season on 4/27 after being closed in August by the previous owners. I just got the pH to 7.5, so I was planning on the transition to liquid chlorine. I'm pretty sure FC hasn't been above much more than 1 since it was opened for the season. I will target FC=6 after sundown to get the OCLT start point. Thanks for all the advice- any other tip/help is also appreciated!!
 
440dodge440 said:
I had the auto chlorintor with tablets on full until a few days ago- I was concerned about getting the CYA too high, so I turned it down to 1/4, and will close it when I get this liquid bleach thing figured out (prior to OCLT). This is all that's adding chloring at this point. The pool was just opened for the season on 4/27 after being closed in August by the previous owners. I just got the pH to 7.5, so I was planning on the transition to liquid chlorine. I'm pretty sure FC hasn't been above much more than 1 since it was opened for the season. I will target FC=6 after sundown to get the OCLT start point. Thanks for all the advice- any other tip/help is also appreciated!!
Click to expand...
Great. As a little background the OCLT is a way of determining if anything is growing in the water. Only two things cause your FC level to go down - UV from the sun (that is what CYA helps protect against) and organics being oxidized by the chlorine. If you take a reading after the sun sets and then a second one before the sun get on the pool you can see if organics are present. Anything over a 1ppm loss in FC overnight tells us that you got something in the water.
 
440dodge440 said:
Hi,
I got my pH at 7.5 and CYA 35, so I'm going to start SLAM. Never having done this before, I plan on adding 3 jugs of bleach (FC=1 to FC=14) and re-checking an hour later. I will be doing this after work, so I have about 4 hours until dark....My question is, how much do I have to stay on top of any chlorine dissapation? If I'm constantly adding bleach to maintain the shock level, do I have to keep doing it into the night, or will the effectiveness of what I did remain until the next day....I'm really trying to understand how important the timing is. The pool water is very clear, but I have very little FC (the water barely turns pink when adding the FAS/DPD powder)

Thanks

20000 gal
Vinyl Liner
DE Filter
Click to expand...

How did you decide on 3 gallons of bleach? I would turn off the chlorinator, and add 1 gallon of 8.25% bleach to your 20000 gal pool. If the water is clear, and at a cya of 35, you need between 4 and 5 FC to maintain it.
 
Defgufman said:
How did you decide on 3 gallons of bleach? I would turn off the chlorinator, and add 1 gallon of 8.25% bleach to your 20000 gal pool. If the water is clear, and at a cya of 35, you need between 4 and 5 FC to maintain it.
Click to expand...
Actually thngs have changed further down in the thread. He is trying to determine if he as an organic issue that needs a SLAM, so he is bringing the FC up tonight to complete an OCLT.
 

Enjoying this content?

Support TFP with a donation.

Give Support
You must log in or register to reply here.
Thread Status
Hello , This thread has been inactive for over 60 days. New postings here are unlikely to be seen or responded to by other members. For better visibility, consider Starting A New Thread.
Top Bottom
Back
Jump to latest Follow Reply