Black Algae, overtaken my pool. Blow it up? Fill it in?

Jul 5, 2008
11
I spent all spring on my mother in laws house and really neglected my pool. I think I was overtaken by black algae.

There are hundreds of pencil erasure size to nickle dime size spots on the bottom of the pool, not on the sides.

My CYA was nonexistent and is now up to 30. My pool is 14x30 with 3ft, 5ft, 3ft depths and greyish blue plaster. Since its shallow and darker, the temp runs around 90 to 94 in the heat right now. (I am in Oklahoma.)

I have been putting my about a gallon and a half bottle of bleach in the pool every morning and every evening. I use a ss brush to scrub the spots and nothing happens. I get in the pool with the 5 inch brush on the pole and have to scrub like your washing sins away and it hardly does anything.

I can't give specifics on the water as I am waiting for my kit to come in.

I am going to try to attach a pic. If it doesn't work, I can text a pic to you, or email.
I am looking for ANY helpful advice, ASAP!
Thanks[attachment=0:2dfw9duk]algae.JPG[/attachment:2dfw9duk]
 

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Please post test results when your kit arrives. It'll be much easier to give meaningful help.

You are going to need a lot more Clorox than you think you will.....I promise. The shock process you undertake may las several days and you will likely consume a lot of chlorine. Stock up. 20 gallons is not too much at all.

Post those test results and we'll all help you get your pool back to sparkling.
 
Seems to me that what your are doing now, adding chlorine morn and eve and scrubbing w/the algae brush, is the right thing and will help keep the BA from spreading while you wait for your kit. :goodjob:

Once you know your #'s, you can hit it hard and start making some real progress.

Now would be a good time for you to add your pool & equipment specs in your sig.
Go to User Control Panel, then Profile, then Edit Sig.
That will help folks responding to your posts.

Don't worry, BA can be stubborn but you can beat it!

Welcome to the forum :wave:
 
With CYA at 30 you will be in good shape for the super shock you will need. I suggest you poke at some of those spots to see if that algae is inside a pit in plaster. Use a toothpick.
 
Received TF 50 kit today and here are the results.

PH 8.2 (I know, too high)
TA 170 150(from a hth kit I bought from walmart last year)
CH 360 420(from a hth kit)
FC 1
CC 1
CYA = less than 20. I purchased cya from Leslies (the liquid kind) and when I had them test it a couple of weeks ago, they told me I was little less than 30. However, this test filled up the tube and I could still see the spot on the bottom.

I have put very little bleach in the pool for about the last 2 days and the temperature has been over 100. I'm guessing with too little cya, the chlorine is gone by the end of the day.

This is my first time at conducting the tests so I hope I've done them correctly.

What else do you need to know to fix this mess?????
 
To check if it is black algae, scrape some of one of the spots off and wipe it on a white business card. If you get a dark green smear it is algae. If not, try holding an uncoated vitamin c tablet on one of the spots and see if it fades.

Bring the pH into range with MA. If the test shows algae bring the pool to shock level with liquid chlorine and keep it there until you pass the overnight chlorine loss test. Keep the pump and filter running 24/7 during the shock process and clean the filter as needed.

If the test did not indicate algae and the vitamin c faded the stain, you will need an ascorbic acid treatment to clear the pool.
 
I tried scraping up the algae and also the Vit C trick. Vit C appeared to do nothing. It doesn't scrape off well. The tiny spot I did get (from the bottom, none on the sides) appear to be green on a white business card.

I lowered my ph to 7.2
FC = 2
My water is from a well and is very hard. I always have to lower the pH, never raise it.
Do I understand I need the FC to be 10 for several days?

This stuff won't scrape off. Like I said in the first post, it takes a beating from a ss brush.

I am using 182 oz. jugs of bleach for chlorine.
 
Sounds like a shock is in order. I'd go with a reading of 30 for the CYA, so your shock level is 12ppm of FC. Use the poolcalculator.com to figure out how many gallons of bleach you need to add, get it in there and test it a half hour later. Test and repeat as often as possible until you pass the OCLT.
 

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Two weeks ago, I added a product called INSTANT CONDITIONER from Leslie's. It was supposed to raise the stabilizer level to 35ppm for 10,000 gallons.
I took water in to Leslie's yesterday to have them test the cya and they said it was low. If fact, I don't think it registered. I used my TF50 kit and could see the dot when the tube was full. I added two pounds of CYA last night into a sock and crushed it with my hands until most of it was dissolved. This morning, I tested CYA again and could still see the dot with a full tube. I will take water back to Leslie's to test again as I only have one more in my own kit. MY QUESTION IS THIS, does the CYA test show results for the INSTANT CONDITIONER. I don't think it does. Am I overdoing it and should I hold where I am at for now?

I've raised my TC to 11.
PH is 7.6
How long do I keep the TC level this high? One day, two days, ?????
 
Do keep track of all CYA you have added, it may still show up on tests. I suggest paying attention to how the pool is holding chlorine now. Are you holding more than 50% in a 24 hour period? If so you are probably OK. Certainly do not add more now.
When I worked on my friends pool that had BA, we took it to shock level for mustard algae and held it for as long as we could given her company coming. I wish we could have kept at it for a week at that level. We also put a trichlor puck on spots and left it on place for ten minutes or twenty. I do not know how long it takes to damage the plaster, so do this if you dare. We took turns scrubbing with SS brush and one day allowed one person (nutty) to go in wIth a mask when chlorine level was allowed to fall to near regular shock levels to pick at embedded spots. Not a wise idea and more time at super shock levels would have been better. After all that, I cannot be sure if she has kept FC high enough to prevent BA return. Same issues that caused it are still at play. That said, we got rid of 90% of it, and the rest may be dead now.
 
tranger2 said:
Last night my FC was 9 and this morning it was 7. I guess that is a good sign the CYA level is OK?

Do I need to keep up to 10 to 12 at all times?
A drop of 2ppm overnight means you did not pass the OCLT, overnight chlorine loss test. That part was consumed by organics. Therefore I would expect about that rate of loss during the day, plus what is lost to the sun. So if that was 8 hrs night, maybe 3 times that in 24 hrs, plus loss to the sun of maybe half at CYA 30- these are all wild estimates you understand. So you can see how hard it its to keep it above 10-12 as you must. (lose 6 to the sun, lose 6 to organics) Too high can damage a liner, so better to test and add bleach as you need to. Your notes will help keep track of the consumption rate.
 
OK, I went and read about OCLT test and ABC's.
My question is this, if I am having chlorine loss overnight based on organic or algae which is causing the TC to drop, could I raise the TC up to a 15 or 18 overnight to kill more of the algae? Would Super Shocking it kill the active algae quicker?
 

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