Black / Brown algae

[David Kol]

From what I've read so far, it looks like I need to get the chlorine up first and then lower the ph a little. I've added two gallons of 5.25% bleach to the pool tonight. Will test in the morning before I have to go out. Based on the readings posted above, I don't think two gallons will get the job done. The more I get to read the less sure I am of what my problem is ( the dark patches on the bottom). I hope to be able to take and post a few pictures.

David

[duraleigh]

David,

Did you get my PM re: your test results?

[David Kol]

Yes on the PM. Test results are above. Total chlorine was up to approx 1.5 PPM this morning. I added two more gallons of 5.25% bleach. Will check when I get home this afternoon.

David

[CarlD]

David:

You are going to need to be far more aggressive to get your algae under control.

1) You need to get your pH down to the lower 7's--chlorine will be more effective. You can use muriatic acid or dry acid, but the muriatic will be faster.
2) 2 gallons of bleach won't be nearly enough. You need to get your FC level up to 15ppm and plan on keeping it there for up to several weeks. You'll need to check your FC level 2 to 3x per day and add bleach as needed. Use MWSmith2's bleach calculator...do a search for it and download it, it's free. Plan on adding lots and lots of bleach over the next few weeks. You can also get liquid chlorine in 5 gallon "carboys" from pool stores. It's usually 12% (exactly twice as much chlorine per gallon as ultra bleach) and you can add a lot of chlorine with it faster and easier and with less waste. But it's usually more expensive than bleach--plus you give a deposit on the carboy. But if it's $12 for the carboy, that's a very good price. Anything under $15 is probably OK.
Remember Liquid Chlorine, liquid shock and bleach are all the same thing--just different concentrations. Regular bleach: 5.25% Ultra/liquid chlorine 6%. Carboys and liquid shock: 12%. PS: Make sure the carboys are recent deliveries because 12% breaks down rapidly to 6%--plan on using it quickly.
3) Brush your pool everyday--you don't have to scrub it and kill yourself and maybe tear your liner, the object is to loosen and open up the algae there to the chlorine.
4) You want to vacuum to waste everyday.
5) Do not use trichlor pucks, or dichlor powder. Your CYA is 30--that's good enough for now. If you want it higher, you can raise it later...Remember, when you are up to your...backbumpers....in alligators it's not the time to think about the objective of draining the swamp....
6) What you need to do is very simple, but not easy. It's not complicated, but it is hard work. You need to be persistant, decisive and patient.

[David Kol]

Hard work is still cheaper then the other option. (( at least when you let the dog in, he quits barking)) <G>. I should be home in an hour an will add bleach / chlorine to get the level up to 15ppm.

Again, thanks to all

\David

[David Kol]

Here are 2 pictures of the problem. These patches are more towards the outer edge of the pool. 24 ft pool, and the problem is fairly well confined to the outer 6 or 7 feet. Approx 6 to 7 feet from the center out has no noticeable problem (yet) As the cl level is increased, the darkness of the patches starts to go away.
I am now working on getting the cl to the range of 15ppm (as suggested here). Should I work on lowering the PH from the 7.9 now, or what until I get the CL level up.

Thanks

David

[gregugadawg]

black algae isn't going to grow in a vinyl lined pool, it needs a rough surface to attach on to as in a plaster surface. Also black algae is going to be no larger than a quarter in diameter. It is possible to be brown/mustard however that easily brushes up but is persistent. Try to rub a vitamin c tablet on the discoloration and see if it comes up, if so then it is a stain.

[David Kol]

Rubbing, scrubing, brushing had no effect on patches last year. This year we have rubbed with the brush on the vacuum head, and you see ZERO improvement.

The readings this morning after adding bleach yesterday based on the calculator, and acid for the ph late last night, are

cl 14PPM
ph 7.4 -7.5
cya 30-35 (subjective to when the black ball is not visable)

david