Fourth SLAM this Summer due to algae. Am I doing this right?

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D

Dagobah

0
Jun 17, 2013
133
Dallas, TX
So I've had to SLAM the pool multiple times this summer, but the algae keeps coming back a week or two after each SLAM. I've just re-read the SLAM page and realized I've been leaving the salt cell on for my overnight FC test (Doh). That's one mistake, but I want to make sure it's the only one.

I'm in the middle of another SLAM right now, and here's where I'm at:

-Began the SLAM Friday. CYA was at 40, got FC to 16 and have maintained.
-Over the weekend was checking FC 3-4x a day
-Today (Monday) was able to check it twice. This AM, FC had maintained overnight (with cell on) but I can still see remnant green algae in the spa that won't seem to brush off. Keeping FC at 16 tonight.

It's a big pool, 35k gal, so I'm using a LOT of bleach. I've literally emptied the two local Walmarts, and most of the local Target of their house brand concentrated bleach. However, that's what it takes to raise FC.

Should I be doing anything else? Would raising FC even higher help speed this up? I'm brushing the pool daily during the SLAM.
 
You can bump it slightly higher to say 18 (or even up to 24 if you suspect mustard algae) or so especially if you're not going to be able to check/dose frequently. I'd leave the cell off until you've fully completed the SLAM, including the OCLT. When dosing with bleach, are you dumping into the pool, spa or both? Dump part of your dose, maybe 1/4th of it in the spa, the rest in the pool, obviously slowly in front of a return in both cases. Remove ladders and lights if possible and scrub them down with a diluted bleach solution as well. They are problem spots for algae to hide.

As far as why it keeps returning, perhaps you never fully completed a SLAM due to SWG usage during OCLT or you were letting FC drop below recommended minimum for your CYA level.
 
I would not treat this as mustard algae, sounds like everyday garden variety green algae to me. Raising the FC to mustard algae levels is not done at this time anyways. Make sure you follow the SLAM procedure and follow up with our guidelines and the pool should be algae free. As a side note remove the lights from their niches and brush out the niches while at SLAM level.

Please post all test results and we can offer more advice. The CYA level is low for a salt pool, but it is fine until you are finished with the SLAM.
 
ping said:
I would not treat this as mustard algae, sounds like everyday garden variety green algae to me. Raising the FC to mustard algae levels is not done at this time anyways. Make sure you follow the SLAM procedure and follow up with our guidelines and the pool should be algae free. As a side note remove the lights from their niches and brush out the niches while at SLAM level.

Please post all test results and we can offer more advice. The CYA level is low for a salt pool, but it is fine until you are finished with the SLAM.
Click to expand...

Didn't see this until today. I went ahead and brought the FC level up to 24 last night, has now been there for 24 hours. Did not pass the overnight test last night, dropped from 24 to 20 overnight with the cell off.

Just tested tonight, it's 8pm, sun is setting. FC at 30 (my last adjustment must have gone over a bit). I've now been at SLAM levels since Saturday (Today is Wednesday night). This is the longest I've slammed it. Will see if it passes the overnight test again tomorrow.
 
Nuvene said:
Yeah generally 4 days is not a long enough slam so I don't think you ever really finished. .. Then not having your cya at the proper level for running your swg it was not nearly balanced enough
Click to expand...

How long are we usually talking? I've emptied both my local Walmarts and a Target of their house brand bleach. (Seriously!)

With a 35k/gal pool, this is taking a LOT of bleach.
 
It depends how bad the pool is... there have been some that takes weeks... after a few days the demand for chlorine does drop... it is worth it though.... after the slam is really complete you will be amazed how easy it is especially with the swg
 
Nuvene said:
It depends how bad the pool is... there have been some that takes weeks... after a few days the demand for chlorine does drop... it is worth it though.... after the slam is really complete you will be amazed how easy it is especially with the swg
Click to expand...

So in every case, my FC has been at 0, but the pool hasn't ever turned green. A slight tint, or just a hint of green, and I've caught it pretty early. I wouldn't consider mine too bad.

Just did the overnight test, and I've dropped from 30 to 22.

I'm performing the evening test at around 8pm. The sun is setting, but there is enough visible light to do the test. Should I be waiting until it's completely dark?
 

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Finally passed the overnight test!

So now I need to adjust a few things. pH is high at 8, and my CYA is low at 40. I plan on using liquid stabilizer, although I still know it can take a little while to work.

Should I adjust pH first, or get the CYA up?
 
The pH test is unreliable (usually will read high) at FC levels above 10. Wait to adjust that after FC drops to below 10 and retest.

Raise CYA now. If you're wanting to hit 70, use Pool Math to determine how much you need to get to 60. Best to under shoot the mark and add more later than add too much.
 
Well, here I am a few weeks later and I'm back to 0 chlorine. Seeing hints of green, and some algae in the spa again. I am positive I did the overnight test correctly last time. I have since brought the CYA up to correct levels. What could have gone wrong, and what should I do now? Mustard algae? On the last SLAM, I kept FC at Mustard shock levels a few days before the SLAM completed. Have also had the salt cell tested, and it's working fine. I am considering just calling a pool company to fix this.

Current test:

FC: 0
pH: 8.0
tA: 180
CYA: 60
 
Well if your seeing hints of green you need to SLAM it. I know this is getting old but.....
If your getting algae again your not keeping your FC in range for the CYA level or you didn't complete the other SLAM.
How long does your pump run ? For your current CYA level for a SWG your FC range should be 4-5 and never below 3. You may want to bump that CYA level up to 70-80 when you get the SLAM over with.
You also will need to lower your PH into the low 7's for the SLAM. Your shock level is 24.
 
Dagobah said:
Well, here I am a few weeks later and I'm back to 0 chlorine. Seeing hints of green, and some algae in the spa again. I am positive I did the overnight test correctly last time. I have since brought the CYA up to correct levels. What could have gone wrong, and what should I do now? Mustard algae? On the last SLAM, I kept FC at Mustard shock levels a few days before the SLAM completed. Have also had the salt cell tested, and it's working fine. I am considering just calling a pool company to fix this.

Current test:

FC: 0
pH: 8.0
tA: 180
CYA: 60
Click to expand...
I know you have a SWCG, but are you testing at least FC and pH every day?
 

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