black algae in pool

[bluekiwi]

I believe I have black algae in my pool, I have tried super chlorinating it and using an algaecide at the same time and it worked only partially. What is the best way to get rid of it, root and all. Is there an all in one product available or is it a multiple of products to be used. Thanks
http://www.flickr.com/photos/104897156@N08/

[kelemvor]

You need to do a few things.

1. Get a good test kit, such as a K-2006 and test your water. You can't determine the right amount of chemicals to add if you don't know what's already in there. Here's a doc that pooldoc created to help you get the right kits. http://www.poolforum.com/pf2/showthread.php?14994 You'll have to order the kit and shipping takes time. In the meantime you can either go to walmart and get an "HTH 6 way" test kit or go to the poolstore with a water sample. Once you do either, post the test results here. Don't buy whatever it is the pool store recommends, you'll likely spend a lot more money than you need and may actually make things worse.

2. Shock the pool. You don't really know how much bleach (chlorine and bleach are the same chemical, just marketed differently and in different concentrations) is necessary until you've completed step 1. Given that it might take some time to get your test results, I'd put some bleach/chlorine in there now. Maybe a gallon or two.

3. Run the pump/filter, and brush the sides daily while cleaning things up. Make sure to clean the filter when it is 10psi higher than were it is immediately after being cleaned.

More specific instructions can be given once you post your test results. Specifically please post:

FC (free chlorine)
CC (combined chlorine)
pH
CYA (Cyanuric Acid aka Stabilizer)
CH (Calcium Hardness)
TA (Total Alkalinity)
Salt (aqua check test strips, or a K-1766 or even the poostore can get you this value) Instructions on getting a kit are on the same page I linked above (http://www.poolforum.com/pf2/showthread.php?14994). Your pool store will likely have salt test strips in stock, too.

Also, post the approximate volume of water in your pool. If you don't already know, here's some instructions for figuring it out: http://www.wikihow.com/Calculate-Swimming-Pool-Volume-in-Gallons

Oh, one more thing. Since you said "super chlorinate" I assume you have a SWCG and set it to super chlorinate to try and shock. Don't do that, it doesn't work very well and will drastically reduce the lifespan of your cell. Instead shock by adding chlorine bleach as I mentioned above. Also, if you have algae and are using a SWCG I'd say something isn't quite right with it. Maybe your salt level is lower than it should be or the cell needs to be cleaned. That is something that you should address after dealing with the algae and getting your pool clean. SWCG are good for maintaining, and preventing problems. Once you've got a problem they're not the best way to go about fixing it.

[PoolDoc]

Your pictures:

https://lh3.googleusercontent.com/-F0UatR6SYxs/UlblJyHlRnI/AAAAAAAAGNQ/NVf-tAECF1o/s800/10177794635_001216e447_sm.jpg

https://lh6.googleusercontent.com/-v6Q8CT8kUTs/UlblJ07gNKI/AAAAAAAAGNY/dp1lxYbuvCg/s800/10177797365_0d724c809c_sm.jpg

https://lh6.googleusercontent.com/-q60PVps66yw/UlblJ0tU3dI/AAAAAAAAGNU/Utm4dCvN5ls/s800/10177862906_ef39962db5_sm.jpg

[PoolDoc]

The things Aaron told you are all good -- most of them without regard to whether there's algae or not.

But, I'd like to request that you do the 'fingernail smear test' to verify that you've got black algae: just scrape a bit of the algae so that it gets under your fingernail, and then smear the collected 'goo' on a white 3x5 card or other heavy white paper. If it's black algae, it will 'smear' dark green.

The distribution of the algae is odd, and atypical of any black algae I've seen, so I want to confirm that that's what's really there, before going too far down the drastic 'kill black algae' warpath.

One other request: when was your pool built?