Does SLAMing really use this much chlorine?

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callmedpit

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LifeTime Supporter
May 25, 2014
54
Millersville, MD
I've been SLAMing (first time ever) now for a couple of days, my CYA is 35 so my FC SLAM level is 14. My water is completely clear and my CC is 0. Yet I still find pretty drastic drops in FC, for example last night at 9:30pm I topped it back off to being 14, checked again today around 1pm and it's at 6ppm.

So I have literally gone through probably $50 worth of WalMart bleach at this point with no end in sight.

Since this is my first time SLAMing, is it normal to have to go through this amount of bleach? Especially considering my water is clear...What have been some of your experiences?
 
A lot of the loss from 930 last night till 1 this afternoon could have been due to sunlight.

If your water is clear and you have zero cc's it's time for an OCLT (overnight chlorine loss test).

If you lose between zero and 1 overnight your are done with the slam. For the purposes of the OCLT the pool should be at slam level and the first reading taken after the sun goes down. The second reading should be before the sun comes up. If you are a late to bed person it can be helpful to take a 1 am reading just in case you don't roll out early enough for the early am test.
 
karmabiker said:
A lot of the loss from 930 last night till 1 this afternoon could have been due to sunlight.

If your water is clear and you have zero cc's it's time for an OCLT (overnight chlorine loss test).

If you lose between zero and 1 overnight your are done with the slam. For the purposes of the OCLT the pool should be at slam level and the first reading taken after the sun goes down. The second reading should be before the sun comes up. If you are a late to bed person it can be helpful to take a 1 am reading just in case you don't roll out early enough for the early am test.
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Either way, the sun shouldn't be eating 8ppm of FC in a few hours of sunlight, this process wouldn't be sustainable if that was the case, right?

So if it gets dark around 9pm and I do a reading at 9pm and another 1am with less than 1ppm loss, it's considered an OCLT pass?

I was testing/topping off pretty consistently yesterday about once every 1-2 hours, and never staying at SLAM level. I'm about to run out of chemicals for all of these tests lol!
 
You would be very surprised at how much cl (above the recommended range) will get burned off by the sun. That is why recommend testing and dosing so often.

"Passing" the OCLT means overnight. I never manage to get up early enough ... My version of passing is a 1 am test with zero loss, if I do roll out early enough I do the real test.
 
callmedpit said:
Either way, the sun shouldn't be eating 8ppm of FC in a few hours of sunlight, this process wouldn't be sustainable if that was the case, right?
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It's not supposed to be sustainable, it's supposed to be somewhat intense and relatively short in duration. If you let the FC level drop below slam/shock it slows down the process and increases the total amount of chlorine required. So far you seem to be pretty much on track - as long as you keep FC levels up consistently the end *is* in sight.

If it helps, think about three phases :

- at the start, chlorine is being used up killing algae AND by the sun -- FC drops real fast, you have to top up every half hour or hour

- after most algae has been killed, FC consumption from algae-killing drops but consumption from sun during the day stays high

- once FC consumption by algae goes to zero-ish (you meet 3 conditions for ending SLAM -- OCLT AND clear AND CC level) you can reduce FC to normal levels and chlorine consumption will go down even further... at this point it will seem reasonable
 
"Either way, the sun shouldn't be eating 8ppm of FC in a few hours of sunlight, this process wouldn't be sustainable if that was the case, right?"

It surely can if you are above your target level and are at slam level. That's a whole different "burn off" curve over the normal ranges.
 
Thanks for the responses and making me feel better. I just going to say, if the sun can burn up this much FC in a few hours during the day, I would be spending like $1,000/month on bleach.

And finally, even though my pool water has always been clear, it's possible that algae is still in here and using up this much chlorine (along with the sun)?
 
callmedpit said:
Based on what? What symptoms would I notice that would make me want to raise the CYA?
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You would find yourself complaining on an internet forum about chlorine usage ;)

Higher CYA (up to a point) reduces burnoff from the sun so can lower the amount of chlorine you need to add even though higher CYA also requires a higher FC level. Downside is that a higher CYA level also complicates things if you ever have to SLAM again. The usual recommendation is 30-50 CYA, with folks in southern states tending to run closer to 50.

Again, this is totally academic at the moment. You want CYA where it is for the SLAM.
 

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Ok this is just getting ridiculous to me. I've already used 16 jugs of bleach:

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I just woke myself up at 2am to do the OCLT and I moved from 22ppm to 18ppm, so I did not pass. I don't know how much more of I this I can take. I just ran out of R-0871 so I can't even test tomorrow if I wanted to. I ordered more from tftestkits.com, but won't be here for a few days...so what do I do in the meantime? What are you supposed to do if it's raining mid-process? If I end up needing to start this process completely over I'm going to drive myself mad. How many more times am I going to have to go and look crazy buying all this bleach from Wal Mart before this is going to get corrected?!?!
 
Are you right out of 0871 or just "almost out" ? If "almost out" you could probably do some things to stretch what you have out, eg maybe eyeballing a 5ml sample instead of 10ml and counting 1ppm per drop of 0871.

From what you've said so far your SLAM is proceeding normally (other than running out of reagent)... every SLAM is different but for a pool your size I would expect to see 20+ gallons of bleach used to get it completely clear.

Rain shouldn't matter unless it carries a lot of runoff from your yard into your pool or your pool overflows. If you know a lot of rain is coming it probably wouldn't hurt to drain off a bit of water in advance to avoid overflow. Other than that, the rain is just one more annoying thing to deal with (sorry).

If you can't test at all for a couple of days, my first though would be to keep adding the same amount you've been adding daily for the last couple of days, or maybe a bit less. Rationale there is that a lot of the chlorine loss is due to sunlight and that won't change (although I guess on the cloudy/rainy day you could probably add a bit less ?) while your loss to organics should continue to drop slowly... keep brushing and keep the pump running.

If you're still losing FC overnight then you have some algae somewhere -- behind a ladder, behind a light, something like that -- and you need to find it to make sure it doesn't come back once you drop FC levels to normal.
 
I feel it is important to remember that your pool got the way it is because of the way you think it should be done. The best thing you can do is ignore your intuition on the subject and have faith that we aren't steering you wrong.

Please do not take this negatively, I can completely relate. However driving yourself mad over a pool is not going to help the process. Take a deep breath, a cool drink, some POP (Pool Owner Patience), and remember that once the process is done you will have a clear pool with far less chlorine demand. A pool that won't go cloudy every time it rains, and will be easier overall.

Sent from my HTC Thunderbolt.
 
Thanks everybody for the words of confidence, I will do my best to keep at it and hope the R-0871 shows up soon.

I think part of the problem for me is that my water is completely clear and has been completely clear. I moved into the house this past winter and it's my first time with the pool. The pool was professionally closed and professionally opened (the water was one of the cleanest they had seen when opened), and we only used "pool chemicals" for maybe 3-4 weeks before I started looking into TFPC because we had a situation where girls legs were getting itchy.

The pool has no visible signs of algae, does not get cloudy when it rains, etc. It just seems like a giant tease that is eating bleach like there is no tomorrow lol. This is a picture from mid-SLAM process:

GvrHkUm.jpg
 
You're basically looking for anywhere that algae might be hiding, so pull the light and clean behind it. The pool sure does look nice, so seems more likely to be somewhere hidden. Does the ladder come out for cleaning ? Anything gross under the skimmer baskets ?

If your pool is still using chlorine overnight then either there's algae somewhere or a raccoon is washing his dirty feet in your pool every night ;)
 
Pull it and clean behind it. Many people will find algae hiding back there eating their chlorine. Read a lot of threads with that complaint and a light being the problem.
Are you still brushing the walls and floor daily ??

YES, it can eat that much chlorine. I was buying 4 bottle 12.5% cases three at a time for the first two weeks. It's still cheaper and in my mind easier than doing Pool Store and tossing in stuff I had no idea what it was.
 

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