Really Hungry Black Algae??

[PopcornGirl2]

Okay, I *think* I understand what's going on, but want to get the thoughts of more experienced pool people.... I haven't dealt with black algae in years (after Hurricane Katrina or Gustav, I believe), but I know it when I see it and I know how hard it is to get rid of it. When I spotted the tell-tale signs two days ago, I didn't say anything; I just hoped my frequent brushing and keeping my FC at 10 ppm would take care of it.
No dice.
So, yesterday, I took extreme measures (not really that extreme) and lowered my pH to around 6 or so using muriatic acid. Before that, I bought a new wire brush and spent about an hour working on the black spots. About an hour later, I added 4 more gallons of liquid chlorine (10.5%) and called it a night. Here are my numbers right before I added the muriatic acid and chlorine, followed by my numbers just now:

Yesterday, ~7:00 PM:
pH: 7.2
FC: ~6.5
TC: ~7.5
CC: 1
TA: 110
CalH: 310
Cya: 50
Temp. 87*

Today, 1:00 PM:
pH: ~6.5
FC: 0 (!!!)
TC: .5
CC: .5
TA: 30 (!!!)
CalH: 300
Cya: 40
Temp: 85*

I know that black algae eats chlorine up like nobody's business, but quite frankly, I am shocked by today's numbers! I retested three times because I thought they were in error. Nope. My chlorine is GONE. That's AFTER adding 4 more gallons on top of a FC level of 6.5! Can black algae really go through it this quickly?? The algae looks considerably better today, but it's still there. I'll do more brushing after this current band of rain moves through.
Oh, the joys of living near the Gulf...

 

[zea3]

Why did you drop the pH so low?

 

[PopcornGirl2]

Why did you drop the pH so low?

I was told to do that, years ago, to help kill the black algae. Was that incorrect?

 

[Razorhog]

I was told to do that, years ago, to help kill the black algae. Was that incorrect?

I've never heard that, but maybe it would help with the "skin" of black algae. SLAM and brush! What kind of test kit are you using?

 

[PopcornGirl2]

I've never heard that, but maybe it would help with the "skin" of black algae. SLAM and brush! What kind of test kit are you using?

Yes, that's what the guy told me then. He was an older gentleman who had been in the pool care business all his life; he taught me the basics of pool chemistry when we first built our pool as I had never had one before. Never thought to question it and he passed away a few years ago, so I can't ask him about it. It definitely worked the last time I was dealing with this, but then again, maybe it was just the high chlorine levels and constant brushing.
I said I wanted to work on toning my arms, but this is getting ridiculous.
Oh, I have the Taylor Complete Test Kit (High Range) K-2005 with the FAS-DPD Chlorine Test (ordered from TFP)

 

[HiddenRiver]

I am going through the same nightmare PopcornGirl2. Gallons and gallons and at least 50 pounds of chlorine granules so far and lots of brushing . Added the solid "Hockey puck" tablets (dichlor?) lately in addition to 8 pounds refresh each night, which seems to be maintaining the free chlorine levels and the algae appears to be gone--afraid to stop maintaining high FC. Good luck with it all! Appreciate those sculpted deltoids!

 

[PopcornGirl2]

I am going through the same nightmare PopcornGirl2. Gallons and gallons and at least 50 pounds of chlorine granules so far and lots of brushing . Added the solid "Hockey puck" tablets (dichlor?) lately in addition to 8 pounds refresh each night, which seems to be maintaining the free chlorine levels and the algae appears to be gone--afraid to stop maintaining high FC. Good luck with it all! Appreciate those sculpted deltoids!

Yes, indeed... LOL! The only positive in this: I can skip "arms day" at the gym!

 

[funandsun]

popcorn girl... I love the avatar! My absolute favorite episode Blink

sorry to hear about the black algae

 

[PopcornGirl2]

popcorn girl... I love the avatar! My absolute favorite episode Blink

Mine, too!! Love David Tennant!

sorry to hear about the black algae

Thank you! Things are looking better. Brought my pH up to 7.0, and TA up to 100, but kind of overshot on the chlorine FC=20 (oops). Hoping the sun will bring it down today; Should I go get some Sodium Thiosulfate?
The good news: Black algae is GONE from steps; still a few small places on pool bottom, but I refuse to give up. SO TIRED OF BRUSHING!!
Went ahead and tested other levels: Cya=50 and CalH: 310 My CC=.5 so that's better. Just hope I haven't caused a major issue with the chlorine so high.

 

[funandsun]

With the rain you are getting and potential debris and the Sun that will be coming right behind the storm, I would suspect you will be fine with just a firm verbal warning LOL

David was by a mile my favorite Doctor.

 

[PopcornGirl2]

LOL! Thanks!

 

[kcindc]

You want to get that PH up fast as a PH level that low can damage your pool and your pool equipment! A PH of 7.2 is the most aggressive ph level while not low enough to damage your pool and equipment. I suggest using baking soda to raise your TA to 70 which will also increase your PH some. After you have confirmed that your TA is 70, test your PH. If your PH is still low, using borax to raise PH to 7.2

Please read the black algae article and in pool school and ask any questions: Pool School - Black Algae

 

[PopcornGirl2]

You want to get that PH up fast as a PH level that low can damage your pool and your pool equipment! A PH of 7.2 is the most aggressive ph level while not low enough to damage your pool and equipment. I suggest using baking soda to raise your TA to 70 which will also increase your PH some. After you have confirmed that your TA is 70, test your PH. If your PH is still low, using borax to raise PH to 7.2

Please read the black algae article and in pool school and ask any questions: Pool School - Black Algae

Thank you, but I've already raised my TA to 100 and my pH to 7.0 (see update above ^^) Added more Borax to get pH up a little more... Yep; already read it and pretty much every other article on this here. I've actually been around (lurker) for about 6 years. This site is a lifesaver! Thanks again!

 

[PopcornGirl2]

Okay, here's where I'm at now... Do I need to be concerned that FC is not coming down as fast as I'd like??
First pic is day after we got home from vacay and discovered our liquid chlorine (from Walmart) was essentially water.
Second pic was after I got pool clear and noticed black algae on bottom.
Third pic is of same area today.


Today's test results:
FC=14
CC=0 (yay! )
pH=7.4 (not reliable, I know)
cya=45
TA=90
CalH=290
Temp.=88*