So it looks like I bleached my Vinyl Liner during my Mustard Algae SLAM

Jump to latest Follow Reply
W

whitlecj

0
Jul 12, 2016
37
Prosperity, SC
I had to SLAM my one year old pool after getting mustard algae. When I started the SLAM, my CYA was at 65 so I brought my FC levels up to 26 until I passed the CC and overnight test. Then I raised my FC to 37 for 24 hours for mustard algae. I went out of town for 4 days after the mustard algae was over and when I got home I noticed that my liner had bleached out. :(. I checked all of my levels this morning and my CYA has dropped to 35??? I assume this low CYA is what caused my liner to bleach if it dropped that much during my SLAM? I have no idea what caused the CYA to fall. I did not check the CYA during the SLAM as I thought the test would be inaccurate. Live and learn I guess, but I am pretty bummed. Anyone have an idea where I went wrong?

Shared album - Chris W - Google Photos
 
Were you doing a lot of backwashing and water replacement during the SLAM? It would help to have your equipment detailed in your forum signature. Edit Signature

How long was your SLAM, including the MA treatment step?

Chlorine can break down CYA over time, but typically it happens VERY slowly. At elevated FC levels for an extended period, it could happen a bit faster. Water replacement is much more likely to reduce your CYA though.
 
I did not do any back washing or chlorine replacement during the slam. We did probably get about 2" of rain one night during the slam but my water level was low enough I did not have to drain any of it out. My slam lasted about a week and half. I will add my details to my signature.
 
whitlecj said:
I did not do any back washing or chlorine replacement during the slam. We did probably get about 2" of rain one night during the slam but my water level was low enough I did not have to drain any of it out. My slam lasted about a week and half. I will add my details to my signature.
Click to expand...

Likely not due to water replacement then. Rain replacement when water level is low is no change in CYA, assuming the water was low only due to evaporation or normal splash-out, etc. CYA loss at high FC levels is documented but that seems awful fast to lose 65 ppm. I'll have to see what I can find on that issue.

Demegrad9 said:
Isn't there a good amount of evidence of algae reducing CYA pretty fast?
Click to expand...

No. The only evidence of biological reduction of CYA is certain soil bacteria that can consume CYA and convert it to ammonia as a byproduct. This would never occur in a pool that has even a minimal amount of chlorine as the bacteria would not survive. This only happens in pools that are closed for the winter or neglected and the FC level drops to zero. There may be algae in the pool when this happens as well, but it's the bacteria doing the dirty work.
 
JVTrain said:
Likely not due to water replacement then. Rain replacement when water level is low is no change in CYA, assuming the water was low only due to evaporation or normal splash-out, etc. CYA loss at high FC levels is documented but that seems awful fast to lose 65 ppm. I'll have to see what I can find on that issue.



No. The only evidence of biological reduction of CYA is certain soil bacteria that can consume CYA and convert it to ammonia as a byproduct. This would never occur in a pool that has even a minimal amount of chlorine as the bacteria would not survive. This only happens in pools that are closed for the winter or neglected and the FC level drops to zero. There may be algae in the pool when this happens as well, but it's the bacteria doing the dirty work.
Click to expand...

It was really a loss of 30PPM right?

One other thing I just remembered is I did throw a little PH lower in the pool just prior to starting the SLAM. My PH was at about 7.8 before the slam and I thought it may rise during the slam so I added some PH lower. Could that have zapped my CYA?
 
No. A little acid or sodium bisulfate (dry acid) will not affect CYA. The only reasonable explanation is testing error for the initial test. Even extremely cloudy water will not throw off the CYA test by a significant amount. I never like to blame testing, but the CYA test is the most difficult to master at first and is somewhat dependent on proper lighting, etc. The accuracy of the test is only +/- 10 ppm.

I'd say you definitely did lose some CYA and elevating FC too high certainly was the problem for the liner bleaching. The only way it could have been prevented is to have rechecked the CYA before the mustard shock, but that's not commonly needed to recheck CYA during a relatively short SLAM, unless there has been a good amount of backwashing. Perhaps that's a recommendation that could be made in the future.
 
JVTrain said:
No. A little acid or sodium bisulfate (dry acid) will not affect CYA. The only reasonable explanation is testing error for the initial test. Even extremely cloudy water will not throw off the CYA test by a significant amount. I never like to blame testing, but the CYA test is the most difficult to master at first and is somewhat dependent on proper lighting, etc. The accuracy of the test is only +/- 10 ppm.

I'd say you definitely did lose some CYA and elevating FC too high certainly was the problem for the liner bleaching. The only way it could have been prevented is to have rechecked the CYA before the mustard shock, but that's not commonly needed to recheck CYA during a relatively short SLAM, unless there has been a good amount of backwashing. Perhaps that's a recommendation that could be made in the future.
Click to expand...

Thanks for looking into this for me. I guess it could have been a testing error although the 65 had been fairly consistent for a few weeks leading up to the SLAM. I assume there really isn't anything I can do for the liner except live with it for 6-8 more years.
 

Enjoying this content?

Support TFP with a donation.

Give Support
Okay, I was just wondering what the density was and it appears to be only 10-15% more than fresh water itself. So bleach not needing to be dissolved should disperse in the pool rather easily and not sink too quickly to bleach the bottom of the pool.

This is in contrast to cal-hypo which takes some time to dissolve and pretty much sinks right to the bottom.

So I'm really not sure what could have caused the bleaching of your vinyl.

It sounds like you're saying it faded the vinyl everywhere though, not just the bottom.
 
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