Clear water, musty smell

[Subscribe1028]

I haven't posted in a while because my pool has been trouble free!! This season opened up late April to a beautiful, sparkling pool. It's been rainy and a terrible spring here in Chicago. My pool has been blue, but had a few bouts of looking like it may go south so I started SLAM. My problem is my pool is sparkly, passes all 3 SLAM criteria, but has a musty smell to it. I'm assuming the algae is just being barely kept at bay? Here's a recent test result, kit in signature:

Water temp 76 degrees
FC 6.2
CC 0
pH 7.4
TA 80
CH 240
CYA 20 (I added 4 lbs earlier this spring, I also use the Pentair Rainbow CYA test kit so I'm pretty confident in my results, also no leak I've only added a small amount of water 1 time since opening)

Thoughts? I know FC is high for CYA but I'm trying to keep it up since there's this musty smell. Do I just need to keep at SLAM level for like 2-3 days after I pass all 3 criteria???

My pump runs 24/7 and IC 20 (I know, undersized but it's what PB installed) running at 100%.

 

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[Subscribe1028]

Sun is setting here now, so hard to get that sparkly picture.

 

[borjis]

As far as "musty smell" is it kinda fishy smelling?
I get that smell when the pool has been covered all week.
After removing the cover and full sun to burn off the CC's for a few hours, it usually goes away.

 

[Subscribe1028]

No, not fishy. Musty. Like the health club shower!

 

[jmikeb]

have you looked in your autocover box to see if there’s anything in there that might cause the smell

 

[Subscribe1028]

Cover pit is clean, cleared everything out at opening. I'm pretty sure the smell is coming from the water. I can smell it on the kids after they've gotten out of the water.

 

[JeanZ1]

I worked in the drinking water industry for years and a musty odor is typically caused by the compound MIB (2-methylisoborneol, for those interested) or geosmin (usually a more earthy/dirt odor). It is associated with blue-green algae (cyanobacteria) that produce it. It is typically noticed either during an algae bloom, or following a bloom as the compound is released from dead/dying algae.

A couple of things occur to me: 1) you may be brewing some black algae (it is a cyanobacteria), 2) if you filled your pool recently from tap water, the compound may have come in with it. If that is the case, vigorous aeration should off gas the compound.

 

[IceShadow]

Just for my $0.02, the pool photos don't look like a clear pool. It looks cloudy in the photos.

 

[YippeeSkippy]

Yes, I've got to agree with IceShadow. That pool isn't TFP clear at all. Got some newer test results?

Could be a nascent outbreak just ready to ruin your 4th of Juily. Lets get on it and help solve the stink mystery!

Maddie