Pool Algae Problem Support

[shotbeck]

Problem: Can't seem to get rid of growth in concrete pool. It is very rough in texture. On the walls of pool it is almost yellowish orange in color but on the tiles at the top part of the pool it is white in color. It feels very rough like barnacles and is very difficult to scrub off. Once you srub it off and vaccuum pool growth re-appears next day. Water sample taken to pool store and everything checks out normal. Tried a chemical called Banish te get rid of green algae which i had problems with, and it removed green algae but the other rough type growth still remains.
FC: free chlorine level
TC: 3.0
pH: 7.6
TA: total alkalinity level
CH: calcium hardness level
CYA: cyanuric acid level (stabilizer / conditioner)
My pool: concrete pool, 16' x 32', 3ft-8ft deep, roman shaped
Pool chemicals: chlorine tablets and granular chlorine,
My pump & filter:sand filter, 2hp pump
Other info: water temp is about 82 degrees, from about 10 am - 4 pm it has full sun, located in florence, south carolina

[scottm]

I can not get my pool water nice and clear. Every morning there is a coating of algae on the bottom of the pool and a green film on top. When I run my vac the pool gets very cloudy. I backwash after the vac has cleaned up the bottom. I've had the pool water tested last Sat and here are the results of the test.
FC 4ppm
TC 4ppm
pH 7.2
CH 110ppm
TA 113ppm
CYA 25 ppm (which I did add another 1.75 lbs of CYA last Sat.)
Copper and Iron 0ppm
total dissolved solids 200ppm
The pool looks ok but not real clear before I vaccum then it looks very bad again. With a bunch of new algae growth last nice I shocked again this morning. Any ideas that could help me get rid of the algae would be greatly appreciated.
The pool is above ground and about 15,500 gallons.
Thanks
Scott

[chem geek]

In the future, please post a separate thread. You should get your own good test kit, either the Taylor K-2006 you can get at a good online price here or the TF100 from tftestkits.net here with the latter kit having 36% more volume of reagents so is less expensive per test. The pool stores do not always do the tests correctly and in particular the CYA test result vary a lot and are often inaccurate (are they using test strips?). Until you know your pool's true CYA level, it's going to be hard to know how much chlorine you will need to add to shock the pool. You could raise the FC to 15 ppm for now, but I suspect your CYA is higher than the 25 ppm the pool store reported. Read Defeating Algae.