SLAM done 2 days ago, lost all chlorine since?

[tacys_lane]

Hi!

Just registered after 2ish weeks of lurking

because....

I followed the instructions for SLAMing my AG pool with 73% calchlor, finished Sat pm to Sunday am with these numbers holding steady:

FC: 5.5
TC: 0.5 (I added potassium monopersulfate 2ish weeks ago before i started learning this stuff, i think thats elevating my TC)
CYA: 70
TA: 70
CH: 300

Kids swam sunday and i worked Monday, tested this morning and FC is 0!!

48 hrs later the chlorine is GONE?

Can it really go from 5.5ppm to 0 in two days with two kids swimming once??

or, as im hesitant to consider, did I not complete the slam as i thought?

thanks!

tacy

 

[mknauss]

Welcome to the forum! :handshake:

You must add chlorine to your pool DAILY based on testing your FC. You also need a proper test kit to do a SLAM Process. You do not have one. Your SLAM level FC would have been 28 ppm with a CYA of 70. Did you maintain that for as long as it tool to pass the three criteria?

I suggest you read Pool School - ABCs of Pool Water Chemistry and consider reviewing the entire Trouble Free Pool School book.

- - - Updated - - -

I just saw you say you have a FAS-DPD test kit, bought seperately.

So be sure to follow [FC/CYA][/FC/CYA].

 

[jblizzle]

Welcome to TFP!!!

I too am unclear if you actually follow the SLAM Process process ... or if you just threw some chlorine into the pool once over the weekend.

It is normal to have to add 2-4ppm of FC every day ... just to cover the losses to the sun. Add in kids and your losses will be higher.

 

[domct203]

Hi!

Just registered after 2ish weeks of lurking

because....

I followed the instructions for SLAMing my AG pool with 73% calchlor, finished Sat pm to Sunday am with these numbers holding steady:

FC: 5.5
TC: 0.5 (I added potassium monopersulfate 2ish weeks ago before i started learning this stuff, i think thats elevating my TC)
CYA: 70
TA: 70
CH: 300

Kids swam sunday and i worked Monday, tested this morning and FC is 0!!

48 hrs later the chlorine is GONE?

Can it really go from 5.5ppm to 0 in two days with two kids swimming once??

or, as im hesitant to consider, did I not complete the slam as i thought?

thanks!

tacy

Welcome to the forum.

I don’t know where you read to use 73% Cal-Hypo to SLAM, but it was not on this forum.

As mentioned, your SLAM FC level is 28ppm based on your CYA of 70ppm. Always use sodium hypochlorite, aka bleach, to perform a SLAM.

Please re-read the SLAM Process procedure, and ask any question you may have right here in this thread.

What is your pH?

Thanks for posting, nice to have you here.

 

[tacys_lane]

My SLAM:

started Sunday 9/1, I had slimy walls and no free chlorine.

I used poolcalculator and added 73% dichlor (8 to 16 oz depending) twice daily to keep my free chlorine above 15 (thats the highest my test would read at the time, but it was certainly above that number) My CYA was consistently 70 (also the highest my test would read). I read that a slam can be performed with any pure chlorine product, did i misunderstand that?

Saw the FC drop significantly the first two to three days each time i tested and added but then on days 4 and 5 drop very little when i would go to test. When the FC of 5.5 held on my OCLT sat to sunday without changing, i figured it had tapered down.

The water temp is 82, its in full sun in Tucson AZ with daytime temps reaching ~105 each day (September in the desert!)

My questions are:

Pretend i completed the SLAM, and let it drift down as i had thought.

Is a small (3500gal) pool in full sun with HOT weather going to lose chlorine fast enough to eat through 5.5ppm in 2 days?

there was no chlorine input those two days, my SWG was bypassed due to a broken connection, and I was not testing or adding for that 48 hr period.

I guess i just didnt expect it to drop that fast after a SLAM, but I'm new at this, so perhaps I underestimate the staying power of chlorine and CYA.

Tacy

- - - Updated - - -

PH is 7.4

Thank you for your greetings and your suggestions!

All your help is appreciated! What a learning curve =)

 

[mknauss]

You could easily be losing 3 or 4 ppm FC without any bather use right now. If the pool had use, then even a bit higher. You must add chlorine daily.

You do realize you should now (if you have the FAS-DPD test in your signature) do a SLAM Process.

Also, the use of cal hypo in Arizona is not a good idea. Your fill water is high in calcium and due to evaporation your calcium rises quickly. I suspect if you test your CH, you should be draining this pool. High CH is not good even with a vinyl pool.

 

[jblizzle]

Without the proper test kit, you can't really correctly follow the SLAM Process process.
How did you ensure you kept the FC above the shock level for your CYA according to the [FC/CYA][/FC/CYA] if you could not test either high enough?
How did you execute the Overnight Chlorine Loss Test to know all the organics were eradicated from the water?

But, let's pretend you did it right (we are in fantasy land now )

Yes the pool would easily loose all that FC in 2 days. Like I said above, you might expect 2-4ppm of FC loss EACH DAY ... and that is with ZERO use.

 

[domct203]

My SLAM:

started Sunday 9/1, I had slimy walls and no free chlorine.

I used poolcalculator and added 73% dichlor (8 to 16 oz depending) twice daily to keep my free chlorine above 15 (thats the highest my test would read at the time, but it was certainly above that number) My CYA was consistently 70 (also the highest my test would read). I read that a slam can be performed with any pure chlorine product, did i misunderstand that?

Saw the FC drop significantly the first two to three days each time i tested and added but then on days 4 and 5 drop very little when i would go to test. When the FC of 5.5 held on my OCLT sat to sunday without changing, i figured it had tapered down.

The water temp is 82, its in full sun in Tucson AZ with daytime temps reaching ~105 each day (September in the desert!)

My questions are:

Pretend i completed the SLAM, and let it drift down as i had thought.

Is a small (3500gal) pool in full sun with HOT weather going to lose chlorine fast enough to eat through 5.5ppm in 2 days?

there was no chlorine input those two days, my SWG was bypassed due to a broken connection, and I was not testing or adding for that 48 hr period.

I guess i just didnt expect it to drop that fast after a SLAM, but I'm new at this, so perhaps I underestimate the staying power of chlorine and CYA.

Tacy

- - - Updated - - -

PH is 7.4

Thank you for your greetings and your suggestions!

All your help is appreciated! What a learning curve =)

A SLAM is performed with bleach, and we specifically recommend against dichlor.

Did you use 73% Cal-Hypo, or Dichlor? Each of those adds something different besides chlorine.

The image below is a screenshot from the SLAM procedure.

 

[jblizzle]

Also were you using PoolMath or the old pool calculator dot com (which is no longer affiliated with this forum)?

 

[tacys_lane]

Thanks for all the replies! This is awesome.

so, i hastily wrote that second reply, and i'm just noticing i said both Cal-chlor and dichlor in my two posts, which must have been confusing. Sorry! i used straight powdered calcium hypochlorite 73%, NOT dichlor.

Jason, yes, I used poolcalc . com, does that effect things? i found it before i found TFP and it had a drop down in the bleach type i used 73% cal-hypo when calculating amount to add. I read (on one of the many pages in my googling) that cal hypo was best for salt water pools (no explanation, just what the site said) and that was what i had on hand to shock with when i started.

Also, i received my DPD-FAS chlorine test supplies at the end of the process (saturday afternoon), so my approach for testing/supplementing my chlorine during the slam process was a little make-shift. I deduced that anytime it tested at or below the 15 (the highest level i could test to with my kit), i immediately went and added the calculated amount of cal-hypo to raise the water back up to the slam level. i did this for the duration of the SLAM. So, while i wasn't able to get exact numbers testing, i attempted to keep the chlorine level "therapeutic", if you will, throughout by adding when low. It seemed to work as described, the slime went away, and eventually i had residual free chlorine that WAS slow to diminish and then stable overnight. And then today it was gone. . .

domct203- See above, and I did read the SLAM a few times to make sure i got had the process down, but when it says "it is best to use" liquid i figured as long as the chlorine didn't contain any other contents besides chlorine, any type would be ok. Is that a misinterpretation on my part? Is it really "you should strictly use liquid chlorine or bleach"?

Good to know that about tucson water! i have repaired my SWG and am going to attempt to keep the FC level stable with that.

Hey guys, on a related note, given the FC loss i experienced, full sun, kids and the small-ness of the pool, is a FC of 6 even a reasonable goal, or should i be adjusting that up? How high could i maintain a FC to accomodate for those extra factors?

tacy

 

[mknauss]

This forum supports PoolMath. There is also a Pool Math app.

In reality, you should never use cal hypo with a SWCG in our area. Test your CH. As I stated above, you may find it very high. It will scale up your SWCG very quickly.

You can maintain your FC as I high as you like up to shock level. We suggest staying in the target range based on [FC/CYA][/FC/CYA],

 

[jblizzle]

You just need to raise the chlorine level high enough such that it does not drop below the minimum for your cya by the next time you test and add more chlorine.

You do not want to use Cal hypo here due to the hard water and high evaporation levels. You can use trichlor or dichlor if your cya is low and you want to raise it some. But outside of that you need to stick to liquid chlorine or the swg.

 

[tacys_lane]

mknauss- I have a product on hand by hth called salt cell saver. would i be wise to use this to protect the cell, now that my CH is extra high?

I added water to the pool due to splash out and evap today. running my SWG overnight and plan to test everything in the morning, get new numbers.

My water is fairly fresh, filled less than a month ago, dunno if that matters for the CH issue.

 

[jblizzle]

Generally we do not recommend adding any products that we are not sure what they are or what they do. I am not aware of any magical chemical to protect your cell. Well maybe perhaps borates.