I'm curious about how long it takes to get a stable clorine measurement after adding liquid chlorine to the pool - see my results

Jump to latest Follow Reply
B

bobby2175

Gold Supporter
Apr 7, 2023
112
Ohio
Pool Size
31600
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
Hayward Aqua Rite (T-15)
Hi everyone!

This is more curiosity than an issue I'm trying to solve.

I'm getting close to exiting my SLAM and my insomnia has come in handy to stay on my chlorine levels through the night. I've noticed that as I approach the end of the SLAM, my chlorine levels tend to rise through the night as there isn't any algae or anything else consuming the chlorine. I'm curious about how long it takes for the chlorine level to stabilize in the pool to get a final reading. I've read in some messages here...30 mins, 1 hour, etc.

Here are some of my results over the past couple of days:

Friday night going into Saturday FCL after last chlorine addition for the night:
907PM: last chlorine addition for the night
1043PM: 22
1140PM: 24.5
603AM: 25

Saturday night going into Sunday
828PM: last chlorine addition for the night
1133PM: 20.5
256AM: 23

Is the rise in the chlorine through the night because the water isn't turning over fully or something else? Is this even possible? What could I be doing wrong?

I have a Hayward variable speed pump running at about 67% with the SWG off and using one of the recommended test kits from TFT and I'm very meticulous in my testing and have the magnetic stir (and I'm the only one doing the testing).

Just looking to learn something!

Thanks.

Bobby
 
My 6AM readings are:
FCL: 22
CC: .5
No visible algae and clear water

With these fluctuations in CL, would you consider the SLAM complete?

Thanks.

Bobby
 
bobby2175 said:
Hi everyone!

This is more curiosity than an issue I'm trying to solve.

I'm getting close to exiting my SLAM and my insomnia has come in handy to stay on my chlorine levels through the night. I've noticed that as I approach the end of the SLAM, my chlorine levels tend to rise through the night as there isn't any algae or anything else consuming the chlorine. I'm curious about how long it takes for the chlorine level to stabilize in the pool to get a final reading. I've read in some messages here...30 mins, 1 hour, etc.

Here are some of my results over the past couple of days:

Friday night going into Saturday FCL after last chlorine addition for the night:
907PM: last chlorine addition for the night
1043PM: 22
1140PM: 24.5
603AM: 25

Saturday night going into Sunday
828PM: last chlorine addition for the night
1133PM: 20.5
256AM: 23

Is the rise in the chlorine through the night because the water isn't turning over fully or something else? Is this even possible? What could I be doing wrong?

I have a Hayward variable speed pump running at about 67% with the SWG off and using one of the recommended test kits from TFT and I'm very meticulous in my testing and have the magnetic stir (and I'm the only one doing the testing).

Just looking to learn something!

Thanks.

Bobby
Click to expand...
You’ve got something wrong if chlorine is rising when none is being added. Are you sure the SWG is unplugged and the pump is running all night? I’d triple check your test instructions.
 
I didn't unplug the SWG, but I turned it off at the Omni panel. I also checked it again this morning because I was questioning myself, but it was definitely off at the panel. Pump is running 24X7. Can it still generate chlorine if it is off at the panel?
 
bobby2175 said:
I didn't unplug the SWG, but I turned it off at the Omni panel. I also checked it again this morning because I was questioning myself, but it was definitely off at the panel. Pump is running 24X7. Can it still generate chlorine if it is off at the panel?
Click to expand...
I’ve read that some models you actually have to disconnect them to be fully off, but that could just be bad memory. Does the FC keep rising if you don’t add any liquid chlorine?
 
Disconnect the SWG to rule it out as adding FC at night.

Be sure you are holding the reagent bottle perfectly vertical, allowing the drop to fully form on the tip (don't force the drop off) and dispense one drop per second.
 
  • Like
Reactions: Mdragger88 and Bperry

Enjoying this content?

Support TFP with a donation.

Give Support
proavia said:
Disconnect the SWG to rule it out as adding FC at night.

Be sure you are holding the reagent bottle perfectly vertical, allowing the drop to fully form on the tip (don't force the drop off) and dispense one drop per second.
Click to expand...
Ok - I've disconnected the SWG to see where I end up tonight. I have FCL at 13. Does it make sense that I could drop from 22 at 6AM to 13 at 930PM? My CYA was 50 this morning and I've been adding stabilizer via sock method since this morning to begin getting it up to 70.

Also have been doing the completely vertical drops.

Didn't add any chlorine tonight, so that variable of how long it takes to spread through the water won't be present either.
 
Last edited:
In daytime, the higher the FC level the faster it will drop in a given time period.
While a drop of 9ppm may seem excessive, with a starting FC of 22ppm you may be okay - if the SLAM is complete.

Are you 100% sure you passed all 3 criteria for a successful SLAM Process?
Water "gin clear" with no visible signs of algae - dead or alive.
Overnight FC loss not to exceed 1ppm
CC test not to exceed 0.5ppm

I wouldn't add any CYA until you sort out the overnight FC issue. But sounds like that is too late now.

Let us know the results of the FC test in the AM.
 
  • Like
Reactions: Mdragger88
Just tested the water (3AM) - FCL was 13.5. I tested it 5 consecutive times just to be certain - 13.5, 13, 13.5, 14.5, 13.5 (the 14.5 should be ignored due to an errant drop of reagent), so it looks like it's holding.

Yes. I feel that that I've passed if the FCL numbers above are acceptable. I even took the SLAM 1 extra day after my CC finally came below 1 just to be sure. I also brushed the entire pool again yesterday specifically looking for algae and there was none present.

What are the ways that dead algae presents itself? I'm sitting here questioning myself if the dust when I brush the plaster stairs or on the tanning ledge are truly dust or dead algae. There is nothing there visible - it just kicks up dust when I brush these shallow areas. It's been like this since we moved here a couple of years ago in those areas - always having this dust.
 
3 am may be a bit early as more hours would give it a better chance to see movement. As long as you test before sunrise you're good.
On another note just use the 10ml fill line for the FC test and count each droplet as .5 , whatever the drop cout is divided x 2 = your FC
 
So, I started the SLAM because I continuously had to add stabilizer in the pool since we opened this year (way more than what was needed) and could not maintain the chlorine levels in the pool (for the past two years).

Of course, the pool shops took us down so many paths - you must have a leak somewhere (confirmed no leak), here's more chlorine, here's more stabilizer, and add some phosphate all the while never questioning that we have a SWG. The chlorine going to zero everyday was always chalked up to the weather and everyone is going through the same thing.

We finally put a stop to it because I started connecting a few dots when I turned up the chlorinator to 100% and still had 0 chlorine and was able to find you guys over here!

I'm new to pools, the pool builder has completely abandoned us and never finished the pool (we can still use it, but things aren't quite right and even holding back $20K in our build contract doesn't bring them back because they are busy building more new pools that are worth more) and we came out of the winter with a lot of issues...scale everywhere, broken tiles, I'm seeing cracked plaster, spa heater not working, and this chlorine/stabilizer issue among others. So, since nobody is around to service pools in the area, my wife and I are trying to tackle all of the issues one at a time with the help of the community here.

I'm now trying to figure out now how to set the chlorinator properly - which is not exactly clear at the moment.
 
Last edited:

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