pH High, TA low, black algae?

Caracat

Well-known member
Sep 9, 2018
67
Houston, TX
My 13-year-old took over pool chemicals while I was sick. Now my pH is unreadable- bright tomato orange. My (not hooked up) pool light also lost it‘s screw & floated out of its home, revealing what looks like black algae in the recess. It doesnt budge when scrubbed- even with a metal brush. The pool looks perfect otherwise- sparkling and clear!

Where do I begin?

FC 7
CC 1
pH ? See photo.
TA 110 2 days ago, 80 yesterday, 70 today
CYA 30 (waiting on order which will get it back up to 45)

Thanks, y’all.
Caracat
 

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Texas Splash

Mod Squad
TFP Expert
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Your pH looks to be on the low end - about 7.2 or so, but that's not necessarily bad. It appears someone added a good amount of muriatic acid recently which caused your pH to be on the low end, and your TA to fall from 110 to 70. While your TA may be acceptable at 70, what we don't see is your CH and water temp. We need those 4 things together help to give us a better overall condition of the water (aggressive or hard/scale). So let us see your CH and water temp.

As for the niche and black inside, if it's not coming off with a brush it's probably organic staining. You can leave the light out and let the chlorine continue to penetrate the staining if you wish. Not a big deal as long as there is no active algae growth. However ...... your CC is a bit elevated at 1.0. That could be from the cloud cover and bad weather in our area the past couple days. I'd watch that. If the CC doesn't fall to 0.5 or less, or it increases, you may have active algae even in the chilly water. If you see anything odd with water clarity or FC dropping, do an Overnight Chlorine Loss Test.
 

Texas Splash

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Can you tell me why pH looks orange instead of pink like usual?
The OTO pH viewer blocks go from yellow/orange when low, to lavender and purple when high. So once you add the 5 drops of red reagent to test, you match what color you have. So as I mentioned above, some acid had to have been added recently to make both the TA and pH drop. Because of those lower numbers and the colder water we are experiencing, your water is slightly "aggressive". What I would suggest is doing a couple things ..... add a (4 lb) box of baking soda which should increase the TA to about 80. That should also help allow the pH to rise a little faster. You want your pH to get back to the lavender area with the cold water. Your pH can go to 7.8-8.0 and that will work just fine this time of year. If the pH doesn't begin to climb back up in the next day or two, feel free to let the pump run and try to create a bit of aeration if possible.

Hopefully you aren't using any chlorine tabs (pucks) as they are acidic and can also make the pH and TA fall. Stick to just pool chlorine (aka regular bleach).
 

duraleigh

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In The Industry
Apr 1, 2007
32,859
Sebring, Florida
The pH looks to me like a testing error. Low pH should be yellow and high pH should be purple. I have never seen the color you posted.

Is the comparator block cleaned and rinsed? Are you using the correct R-0014?
 

Caracat

Well-known member
Sep 9, 2018
67
Houston, TX
Is the wire insulated or bare?
Apparently the previous owners shoved a housing & bulb in the recess just to fill the hole and make it look nicer to help sell the house. I first removed the light last year for a SLAM and found the wire shown in the photo. Wires (3 altogether, I think- can’t see without getting in the frigid water) weren’t attached to the light at all, just tucked back inside there. The sellers disclosed that no electricity runs to the light. I have no idea when it last worked, where the connection ran, or how/why it was cut. Pool and house built in 1961. We’ve only been here for two years. All that to say, I don’t know much about this light, including whether it’s insulated or not.
 

Texas Splash

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All that to say, I don’t know much about this light, including whether it’s insulated or not.
Not the worse thing. I suspect it's off at the breaker (if even connected) so that should be fine. Next season, if you chose to pursue having a new light installed, a new set of wires (from niche to equipment pad) and perhaps newer LED light can be installed. James thought perhaps the black stains might be copper from those wires. Once the water warms, you can try a quick test by applying some dry acid in a thin sock or nylon to the stain. Dry acid should cause a copper stain to fade.
 

JamesW

TFP Expert
Mar 2, 2011
16,599
The green wire is the ground wire. I was wondering if the green was from green insulation on the wire or if it was from corrosion of copper, which is also green.

I'm thinking that maybe you're getting excessive corrosion due to a stray current.
 
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