Can too much chlorine be my problem?

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DeptOfMeteors

Well-known member
Jul 8, 2020
122
Ottawa
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-15
I've been attempting SLAMming for a couple of weeks now (I keep getting interrupted for one reason or another) and I'm wondering if the problem can be too much chlorine. Because of some bad data I collected, my FC got up to 40ppm one time! That should have been enough to kill a herd of elephants, but the algae seemed to hold on. But I also found out that my CYA was up to 60ppm, which is also more than I thought. So I've been making 24ppm my target. But I still find algae after several hours and the FC dips in to the teens. In fact, in less than 24 hours, it went from 40ppm into the teens.
Another weird development is that my CYA is down to 50ppm. I don't know how that could have happened either, since I haven't done a backwash since adding the CYA. (The wife and I agree that the dot was visible at "50" but not at "40") However, if my CYA is 50ppm then PoolMath tells me I should maintain 20ppm and not 24ppm. Is that my problem? I'm giving algae enough chlorine to thrive instead of die???
No, I haven't done the overnight test. I want to be more confident that it's gone before I make such a commitment and since I still see algae showing up on the floor, I assume I still have it.
 
No, there is no point where chlorine changes form a poison for algae to food. The only issues with "too much" chlorine is that it can be harsh to some things like seals and you loose a lot more to UV rays of the sun.

Now, is this algae you see?

Have you been brushing it every day during the SLAM?
 
I brush it as soon as I see it and I can. I have to wait a few hours sometimes on a sunny day, because I'm very photosensitive, like a 21c vampire. I definitely get it when the sun goes behind the houses so it only manages to enjoy a few hours. Then I test and maintain. I find it quite amazing how resilient this algae is.
 
DeptOfMeteors said:
I brush it as soon as I see it and I can. I have to wait a few hours sometimes on a sunny day, because I'm very photosensitive, like a 21c vampire. I definitely get it when the sun goes behind the houses so it only manages to enjoy a few hours. Then I test and maintain. I find it quite amazing how resilient this algae is.
Click to expand...
Well, my next question would be - are we sure it is algae? Any possibility of a stain of some sort? Copper? Iron??

How clear is the water?

Time for that overnight test to see what is happening.
 
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That's actually a pretty good question, which is why I took this picture. Sorry, but it looks a little clearer in person. Thing is, it looks like algae but it's got that faded green look, like after I've killed it. That was my experience w/my last pool.

The water is perfectly clear right down to the algae on the floor. It's been like that for over a week.

If that's really the last option... I find it difficult to judge the CC. It often looks like there might be more than 0.5ppm, but it's taking me a while to do that test properly.
 

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Ignore CC. It may or may not appear in a pool with algae. CC is eliminated by the UV of the sun, so it may be gone before you test it.

One of our experts her @Donldson seems to agree - is it algae?

The overnight test will tell us is anything organic consuming the chlorine ....

If not, I'd look at metals

Metals - Further Reading

www.troublefreepool.com www.troublefreepool.com
 
While that's not a great picture (hard to get pictures of stuff underwater so no judgement there) it does look like it might be organic but probably dead.

I do agree that an OCLT is probably warranted now. It might be algae, it might be dead algae, it might be something else organic, or it might be something non-organic. An OCLT will help us narrow that down and decide the next step in narrowing down the possibilities.
 
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I tested the FC last night at 9:30pm and got an even 20ppm. Then I got up before sunrise and it was 17ppm. I was expecting to be off a little bit due to testing errors, but my accuracy is much better than 3ppm.
I read the article on metals, but I guess it's moot at this point. When I grasp at straws, the best I can come up w/is that all that abortive SLAMming in weeks past created a stronger breed of algae.
 
DeptOfMeteors said:
I tested the FC last night at 9:30pm and got an even 20ppm. Then I got up before sunrise and it was 17ppm. I was expecting to be off a little bit due to testing errors, but my accuracy is much better than 3ppm.
I read the article on metals, but I guess it's moot at this point. When I grasp at straws, the best I can come up w/is that all that abortive SLAMming in weeks past created a stronger breed of algae.
Click to expand...
Doubtful-
There are a few reasons slam can be drawn out / take a long time.
Not having an accurate cya reading so not actually reaching slam level fc is one of them.
Not checking/scrubbing all nooks & crannies & assuming high fc levels will take care of hidden algae.
(The sign of this is generally a crystal clear pool that fails oclt)
Not brushing/ vacuuming daily to disrupt the biofilms algae uses to protect itself from chlorine.
Also, sand filters take the longest to clear debris/dead algae, there are steps you can take to help your sand filter:
*Doing a deep clean of the sand

Deep Cleaning a Sand Filter

This post will walk you through the anatomy of a sand filter, and then provide a video at the end for how to deep clean your sand filter. The filter used in the photos and videos is a Hayward S180T top mount sand filter. The images are of a similar filter. Obviously not all filters are...
www.google.com www.google.com
* adding DE to the sand filter to help catch the finer material
www.troublefreepool.com

Add DE to a Sand Filter

A clean pool filter will increase the efficiency of your pool! ... your filter are to backwash it, clean the manifolds and grids, and add new DE.
www.troublefreepool.com www.troublefreepool.com
* vacuuming to waste - if the “dead” debris reoccurs then u obviously have more algae to kill
 
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Btw - the slam process can take a week or more in a clear pool - at this point you are a little over the week mark & were possibly not reaching slam level for your cya for the first couple of days. I wouldn’t consider this to be an extended SLAM Process at this time. Gotta have that POP! - Pool Owner Patience :epds: You’ll get there!
 

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I really hope that's it, because I don't feel like taking drastic measures, like cracking open my filter, then finding that doesn't work either (I don't have a hose that's long enough anyway).
I haven't done a backwash in a while (because my pressure gauge is rock steady) so I'll try that and vacuum to waste. That might also serve to reduce my CYA a bit.
 
DeptOfMeteors said:
I really hope that's it, because I don't feel like taking drastic measures, like cracking open my filter, then finding that doesn't work either (I don't have a hose that's long enough anyway).
I haven't done a backwash in a while (because my pressure gauge is rock steady) so I'll try that and vacuum to waste. That might also serve to reduce my CYA a bit.
Click to expand...
If pool store potions like floc or clarifiers were used in the past the sand can be clumped together & not filter well or channeling can occur.
Deep cleaning of the sand is periodic maintenance that should be performed yearly or so. By doing this & not using things like clarifiers/flocs (ie following tfpc) the sand should last a lifetime
Doing a yearly/ every other year deep clean also gives u the opportunity to inspect the parts of your filter & ensure the sand level is correct.
 
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Are you saying I don't need a backwash? If not, then the only new measure is vacuuming to waste. And drawing the SLAM out even more, of course.
BTW, I've been giving you guys the wrong pool capacity. According to the measurements of chlorine I've been putting in and the rise in FC 30 minutes later,
this is it 👇👇👇
 
DeptOfMeteors said:
Are you saying I don't need a backwash? If not, then the only new measure is vacuuming to waste. And drawing the SLAM out even more, of course.
BTW, I've been giving you guys the wrong pool capacity. According to the measurements of chlorine I've been putting in and the rise in FC 30 minutes later,
this is it 👇👇👇
Click to expand...
I meant you don’t need to deep clean the sand filter since it’s brand new.
You should continue to backwash when pressure rises 25% over clean pressure during slam & in the future.
 

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