Think I may have found my FC demand issue?

zamboniman

Well-known member
Apr 30, 2013
52
Chicago IL
Not saying conclusively BUT....

I've been chasing a FC demand issue that maintaining shock levels for days wasn't taming. Have been losing about 6ppm FC per night while trying to achieve the OCLT.

Pool is sparkling as if there is almost no water in it. No CC or less than .5. Still consuming with no end in sight.

Head scratcher here that has me looking for what am I missing. I've never had the light out since we bought the house a few years back. It has 2 bulbs in it and one is burnt out. Decided to take a looksee...

Well without further delay.. Here's what I came up with.

Could this finally be the end?? Well I have some cleaning up to do here. I'll report back to see if we begin to make headway




A word of advice here is that if you are chasing something that isn't making sense maybe check the light niche. I must say this was an absolutely disgusting find.
 

y_not

Well-known member
Jul 24, 2012
1,086
Redmond, OR
*Jed Clampett voice*
WWWWYYYYYIIIIIIIIBBBBEEEEEEEE!!! THAT'S DISGUSTING!!

So glad you found that, that's just downright gross!!! Thank the Lord for chlorine though. It has been keeping you safe from......*points finger at the black lagoon monster* THHAAAATTT!! :shock:

It's a bit hard to tell from the pics, is that almost black algae, or is there moss and dirt in there too?
The way it is strewn all over the pool, it looks like it just JUMPEDout of there when you opened it up. Yeah?

I'd say It's time for a new gasket or some rtv. ;)
 

zamboniman

Well-known member
Apr 30, 2013
52
Chicago IL
y_not said:
It's a bit hard to tell from the pics, is that almost black algae, or is there moss and dirt in there too?
Hard saying I've never tangled with black algae before. This was very blackish.. or super dark green. almost dirt/mud like slimey and falls apart easy which I think is a good thing. However, some of the stuff was (still is) pretty hard to get off the surface of the niche and light enclosure. I was scrubbing and rinsing the light on the pool deck and the stuff dries hard and flaky like I think normal green algae tends to do. A few hours now of exposure the stuff I couldn't vacuum or haven't gotten to looks to have lightened/bleached out some (another good thing I think). The niche is shiny mostly, when I started it was all uck. The thing is that the stuff doesn't just wipe away and there are lots of crevices etc that will be next to impossible to get an agressive brushing into for various reasons. I'll let it cook overnight see what it looks like in the morning, and take another pass at it tomorrow. It has to be much better than before

I think :shock:
 

zamboniman

Well-known member
Apr 30, 2013
52
Chicago IL
y_not said:
The way it is strewn all over the pool, it looks like it just JUMPEDout of there when you opened it up. Yeah?

Basically did jump out.. that all was what "fell" out from taking the light out. It got worse when I started scrubbing it out.
 

zamboniman

Well-known member
Apr 30, 2013
52
Chicago IL
One other thing.. I wonder how much of this wonder goo is hiding up the conduit? I'm half considering pulling the wire out and running some type of brush up that pipe.??? Probably the best thing to do... then I could soak the fixture in a bleach bucket and get it really clean (if I decide to keep this). I broke the motor wires pulling it apart. So I'm at the intersection of bite the $500 bullet for a new fixture or try the repair kit motor and gasket for $100 and hope it works.
 

chem geek

TFP Expert
LifeTime Supporter
Mar 28, 2007
12,083
San Rafael, CA USA
If it's algae, it won't grow too far up the conduit because there won't be any light there. Behind the light niche there is still dim light. It's usually where yellow/mustard algae likes to grow and hide out, but what you have does look more like black algae. If it smears dark green on white paper, it's probably black algae. That's why it's hard to remove on some of the surfaces -- it has a waxy surface layer that is chlorine-resistant so you need to scrape that off to let chlorine attack what's underneath.
 

y_not

Well-known member
Jul 24, 2012
1,086
Redmond, OR
For some reason I find this all very exciting to watch. ::epds::

zamboniman, I don't envy your situation, not fun, but at least you found it! :goodjob:
I would suggest leaving the exposed light fixture in the shock level water so the CL can work at it, scrubbing it periodically.
 

zamboniman

Well-known member
Apr 30, 2013
52
Chicago IL
Quick question.. "IF" this is the dreaded "Black Algae"... what will the "dead stuff" look like?

Of the various black "ICK" that was stirred up in suspension yesterday, today was settled as a light pale green debris that I vacuumed up. (I have the pool at wicked shock levels as my liner has spotty bleaching anyway from previous owners preference of tossing chemicals in and letting them sit). Just wondering if the appearance of this stuff being killed off will help indicate what it may have been.

Thanks,
 

chem geek

TFP Expert
LifeTime Supporter
Mar 28, 2007
12,083
San Rafael, CA USA
Black algae still looks very dark when initially killed. It's not like green algae that generally (but not always) turns gray/white, at least not all at once. It will bleach out, but takes longer though brushing it regularly to scrape off the waxy surface layer to let chlorine expose deeper levels helps. After you scrape of the surface layers, you expose the rest to somewhat elevated chlorine levels and it will eventually fade over time. It grows slowly so the chlorine killing it slowly is still faster than it can grow.

The problem will be that you have some inside the light niche and that doesn't get very good circulation. So you'll want to try and get rid of it as best as you can.
 

zamboniman

Well-known member
Apr 30, 2013
52
Chicago IL
So I think I'm far better off today than yesterday. "I think LOL"

The niche is at least metal looking where yesterday it looked like a muddy hole in the side of the pool open to the earth but there are still some stubborn areas and brushing in there is difficult. Its difficult to tell if it's this gunk or corrosion in areas. The outer niche ring that you see in the pool is mostly corroded from what looked like it was once chromish. The hardest parts are where the liner is cut but still protrudes past the seal. It is curled over and there is some growth in that curl. I'm contemplating cutting the liner closer to the lip so that curl isn't there.

I just completed another scrubbing then toss more 12% in dumping the whole gallon right over the niche area and swirling it in there. My plan right now is to leave the niche exposed until I pass the OCLT. Since the fixture needs some TLC and it's easier to work on off the pool deck I'm thinking I'll just pull the wire out from the conduit all the way (pulling a string with it). Then futs around with that separately to see if I fix it or replace it. I've got the ring and other exposed parts soaking in a bucket of super chlorine right now. If I fix the fixture I'll soak/scrub the whole back thing in a bucket of super chlorine prior to putting back in the pool. In reality we use the light very little anyway it's just nice to have for the random night swim if kids are over. I probably use it more as a night light when I'm doing maintenance after dark. I could potentially rig it back together and not have it change colors anymore as a cheap fix. Or see if I want to drop the coin on the replacement motor. That's a whole different conversation though. The key is I'll be leaving that niche open to the pool for the foreseeable future which could only be a good thing.

One thing is for sure I'll be doing a regular light pull out as ongoing maintenance if for no other reason than to get some fresh water back there and a little brushing. Now that I know how easy it is to pull it only takes 30 seconds to get it out.

Well that's it for today's episode of "As the Impeller Turns"
 

Jeetyet

Well-known member
Jul 29, 2012
200
Florida Panhandle
If you have a return close by and can point it directly at the niche while the light is out that'll help to clean out all the nooks and crannies and if you can keep it pointed that way after replacing the light it should help to prevent future "infections". Though not quite as nasty as yours, I had the same problem last year but since re-aiming the return its been squeaky clean in there.