Started Slam...how soon to add more chlorine

[JillKC]

First time slaming. A bit confused.
Been reading 0 FC for days. CYA is 40. Started slam process this evening with 2G of bleach (12.5%).
Waited an hour and just tested. FC is only 6. CC is .5.
I was supposed to get to 16 FC. Do I add more bleach tonight or wait to see what the FC is in the AM?

 

[Major_in_MS]

What kind of test kit are you using?

 

[JillKC]

TF-100.
FC is done with 10ml of pool water and DPD Powder (R-0870) and FAS/DPD drops (R-0871).

 

[Major_in_MS]

Ok, good test kit.

To answer your question, Yes, you should add more chlorine now. At the beginning of a SLAM, if your pool has a lot of algae/organics then you will burn through a lot of chlorine pretty fast.

 

[Major_in_MS]

Every time you test your FC, you should plug that value into pool math and then add the recommended amount of chlorine. Also old chlorine/bleach will not be as effective as new/fresh chlorine. That's why I always check the date code on the bottle when I buy it.

 

[Newdude]

Hey Jill !! Anytime you add, give it 20 mins of circulation and test again to verify you reached your target. Older bleach won’t do what you wanted it to and you’ll need to keep adding until you get where you wanted to be. But you can gauge how far off you were the first time and go from there.

Every 2 hours is best at first. An icky pool can burn through FC and anytime spent below SLAM target is that much longer the process will take. After 1 day of babysitting it usually holds for 4-6 hours to free you up a little on day 2. For most people it will hold long enough to go back to work on Monday if they Started the process on a Saturday.

If you don’t have the time to babysit it right away, there is no harm until waiting for the next time you do. Without the proper attention you will be wasting a lot of chlorine until you do have the time, so just add 5 PPM per day so it doesn’t get any worse.

 

[JillKC]

Thank you! I just reached SLAM level of 16. Did a little happy dance. My pool is clear, just not able to keep any chlorine. I'm hoping this will prevent an algae bloom if that's what cooking.
Your advise is reassuring as I have to work today. I'll check again tonight and pray that I have enough chlorine to get through. Places around here are selling out.
Thanks again.

 

[Newdude]

So……. A little explanation of why you need to ‘M’ (maintain) through the SLAM. Algae can grow and erase any gains if you drop too far below the target. So you end up spinning your wheels. It drags on and a lot of folks get frustrated and try something else. (The absolute worst thing you can do). It’s totally ok, and life gets in the way for all of us, but if you know the how’s and why’s you can save yourself a lot of headache.

Any killing of algae is a good thing and makes the eventual full blown fight easier, but all situations are different so we can’t tell you exactly how much time, effort and chlorine you’ll be wasting. So we recommend limping along with 5ppm until you can hit it hard *and* often.

 

[Bperry]

Thank you! I just reached SLAM level of 16. Did a little happy dance. My pool is clear, just not able to keep any chlorine. I'm hoping this will prevent an algae bloom if that's what cooking.
Your advise is reassuring as I have to work today. I'll check again tonight and pray that I have enough chlorine to get through. Places around here are selling out.
Thanks again.

If your water is clear, you have less than 0.5ppm CC and you started the SLAM process due to excessive chlorine loss then it looks like you already have two of the three criteria to stop the SLAM done.

So your next step is to raise the FC to SLAM level tonight after the sun goes down, measure it, then measure it in the morning to see how much was lost in the dark. If it’s less than 1ppm, you don’t need to worry about finding more chlorine(at least as much as you’re need for SLAM process), because you’ll be done.

 

[JillKC]

Dumb Q... I manually vac (no robot) should I get in the pool at these levels?

 

[Newdude]

You can swim at FC up to and including SLAM levels if you can see the bottom (for swimmer safety / drowning concerns). Algae is unsightly but harmless.

 

[JillKC]

A couple days into SLAM now - I really appreciate the guidance here! Been adding 12.5% liq bleach as directed by the app. My target is 16. Been at 20 for the past 2 readings (5-6 hours). Hoping for overnight stability (*fingers crossed*).
Water remains clear.
Any cause for concern that FC is over the SLAM target?

 

[Major_in_MS]

Any cause for concern that FC is over the SLAM target?

A little cause, over SLAM level for prolonged periods of time can cause your vinyl liner to fade some, and it can damage swimsuits, especially those really expensive sheer ones that some women like to wear. It can bleach out some equipment, the power cord on my robot is now a pale blue instead of a dark blue. The bleaching of the liner is probably the biggest concern, unless you have a bunch of those expensive swimsuits.

 

[JillKC]

Lol! I literally have a "pond suit" that is reserved for pre-pool ownership swimming in our pond & creek so nothing too fancy here
I was more concerned about the heater - that's way pricier than all my "good swimwear"
I'm predicting we will drop down to target overnight anyway.
Thanks for the feedback.

 

[Major_in_MS]

Ben Powell, the guy that developed the "Best Guess Swimming Pool Chlorine Chart" which is the precursor to our "Chlorine/CYA Chart"
states:

PoolSolutions Best Guess Swimming Pool Chlorine Chart said:

Caution: orange levels are generally harmless to naked swimmers, but can be quite damaging to swim suits. True competition suits, all polyester or all nylon suits are resistant. Very expensive fashion suits are NOT resistant!

Caution: red levels are can be irritating to skin, can
damage hair, lighten pool liners and are very damaging to swimwear. Additionally, at these stabilizer levels, chlorine will drop VERY slowly. This can make the pool unusable for a long period.

To see the levels he is talking about in this quote please follow the link.

 

[JillKC]

Just providing an update...still in SLAM (since Sunday evening). Did a full test panel and #s are good, TA is a bit high at 100. CYA has held steady at 40. PH 7.2 and even with a hot sunny afternoon, the FC was 14.5 so I think I'm in the homestretch. Just added enough to get to SLAM of 16.

Water remains clear & clean.

 

[mknauss]

Only test FC during SLAM. The pH test is not valid. The others are not needed.