Algae problems

Robbsclassics

0
In The Industry
Aug 1, 2013
6
Batavia and Cortland, NY
I've been getting a lot of good info on this site. I'm getting more perplexed. I am working on a pool for a guy. I believe it is 48,000gal. Yesterday I put in 20gal of chlorine to kill algae. The free chlorine is more than 20ppm as far as I can figure with the cheap Walmart test kit. The local pool store told me my phosphates were very high, and they have a $42 quart to lower it.... I didn't buy it. Last time, I put in 20gal the water went from green to white and was fine until no one put chlorine in the pool for a week. Should I get more chlorine today, or should the 20gal be enough. My friend (the owner) is getting tired of putting money into the pool, and I want it to be as clear as it was. Thanks in advance for any info.
 
Welcome to TFP.

What you did is not the proper way to kill the algae. If you really want to help the owner you'll suggest they get a good test lit and either you or they learn to take care of the pool correctly.

Adding 20 gallons of 10% bleach would raise the FC by 40 ppm. If it's 12.5% bleach it would have added 50 ppm FC. Without knowing what the CYA in the pool is there's no way to know if that was way too much or not nearly enough FC.
 
Depending on the CYA level, all that bleach may still not have raised FC to shock level. If the pool has been chlorinated using pucks and powders, there's a good chance the CYA level is over 200. When I took over my pool, I was somewhere north of 220 CYA.

That's one point. The second point is that a one-time megadose of chlorine may shock the algae, but it is probably not a fatal shock - it was just stunned. It will be back.

Rather than belabor it and spend hours typing, I'll just suggest you spend a little time in Pool School and learn some of the basics about water chemistry and the CYA/FC relationship and the SLAM process.
 
My CYA is about 40. Ph is 7, FC is off the chart, TA is 50. I just got done brushing the entire pool, and it's looking much better.

I know the cheap testing kit sucks, but its what I have now. I will try to convince him to get a real testing kit. When I had problems before, I read up on here and got everything in tolerance. Then shocked the pool, and it was nice and clear. This time seems to be different somehow. I have read a lot of the BBB, SLAM, and opening a pool from here, but missed a few articles. I'll read them now.
 
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