SLAMing - Water is Crystal Clear but brushing still turns up brown

I have been SLAMing the pool for the last 5 days, and our water has gone from murky green to crystal clear/blue. The overnight FC loss is 0.5 ppm, so I think all the algae is dead and gone.

My question is this: with the water appearing crystal clear, I do not see any film or anything on the sides and bottom of the pool, but when I brush it, it stirs up a brown cloud that quickly settles. What is this? Algae residue? Should I be worried the algae is still alive? The CYA level is 97, and the pool has held a constant FC level of 26 to 28 for the last several days.

Any ideas?
 
I imagine it may be dirt/dust and some dead algae. Can you vacuume the pool if you have a vacuume?

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You could also follow the steps to add DE to your sand filter. I know this helped my pool tremendously! You need to make sure you are home to watch the pressure on the filter though as it can rise fast.
 
I didn't think the brown cloud was dirt because 1) you cannot see it sitting on the sides and bottom - the pool looks spotless until you brush it; and 2) it doesn't seem to resettle or fall back down to the bottom like you would expect dirt to do.

Having said that, I do live in the dustbowl, and dirt is in the air all the time.
 
Down here I see it all the time with just the slightest winds. Cotton fields nearby, all around. I know you have a couple of those up that way. :D With the winds we've had early this week, I bet that's what you are seeing.

If you run the fine filters in the Z5, you'll be amazed how dirty they get even when the pool looks clean. This dust is very fine and takes a while to settle, but it will.

Did you pass the other criteria to pass and finish the SLAM procedure?
 
Yes, I passed the other criteria to pass and finish the SLAM - the water is clear, the CC is 0.5 or less, and the overnight FC loss is less than 1.0 ppm.

The CYA reading is from the pool store analysis and which was performed before I started SLAMing.

Yes, the pump has been running 24/7 during the SLAM.

I will try using the fine filters for the Z5.

Thanks everyone!
 
This often is a bit confusing. Your water is not clear if you can brush stuff up off the bottom so your SLAM is not yet complete.

I do not think you have to redo the SLAM. I think the algae is dead but still on your pool floor (and some more is dying because you didn't have enough FC) and not in your filter.

I would suggest....

1. Holding your FC up around 20 or so until you get all that visible stuff out of your pool.

2. Brush and vacuum often. Stir up the water. You need to get the junk suspended in the pool water or vacuum it out of there.

3. Once all the visible stuff is out of your pool, perform another OCLT and confirm that you pass all three criteria again.

For what it's worth, you never reached SLAM value for chlorine. With a CYA of 100, 39 is the SLAM value.
 

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Do you have one of the recommended test kits? If so, have you tested your CYA yourself? If not how are you doing your testing?

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Wondering the same thing myself. If you don't have a test kit, how are you performing an OCLT?
 
I do have the FAS/DPD test kit, which is why I am able to perform the overnight FC loss test. My test kit has also confirmed the CYA reading the pool store gave me, so sadly, I'm afraid my CYA really is that high.

Yes, the necessary FC amount to SLAM a pool with 97 CYA is 39 FC, but the SLAM instructions also mention that a lower amount of FC can be used to SLAM, but that the lower amount just takes longer to kill all the algae.

I haven't been able to brush and vacuum in three days due to rain and my kids' extracurricular schedules, but I will get on that ASAP.
 
Can you point me to where this is stated? I am not seeing it.

The only place this is stated is in the CYA/Chlorine chart page: http://www.troublefreepool.com/content/128-chlorine-cya-chart-slam-shock where it says:

... At high CYA levels it may be impractical to use such high FC levels, lower FC levels are often sufficient though they take longer to kill algae. ...


Lowering CYA is a better idea than extending the process by using lower FC levels with a CYA that is too high to maintain properly after the SLAM is complete. It's not recommended.
 
JVTrain quoted the sentence to which I was referring (contained in the CYA/chlorine chart). For what it's worth, as a newbie pool owner, that sentence in the SLAM article did give me some comfort knowing that the pool could be slammed at lower FC levels than what was indicated. I was really freaked out thinking that I would have to get the pool up to FC 39 to properly SLAM it. Even now, with my FC at 25, I'm still nervous and wondering what it will do to our pool equipment. Obviously, the only real solution is to get down the CYA, but in the meantime, it was helpful to know, especially since we needed to jump on the algae before it got completely out of hand.
 
Well that article has now been edited to remove that sentence because it was not accurate.

The CYA acts as a buffer, so the pool and equipment will be fine. The SLAM process was designed to be safe for the pools ... unlike when pool stores tell you to drop a nuke load of chlorine in at once.
 
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