algae help

[bcrumb]

Inground vinyl pool. 28k gallons. 5 years old. Water clear, algae growing in some areas on liner/ladder/lights. Alkalinity and ph about normal. Salt system. CYA reads zero and free chlorine .5ppm. Inside of salt cell and pipe jets has rusty or black looking coating. Some rust stains on skimmers also. Is salt cell bad? Do I just need to add CYA? Already have had SWG on super chlorinate for 30 days and still only reading .5 ppm chlorine. Salt level at 3200ppm.
Thanks for any suggestion you may have.

[JohnT]

Shock the pool first, preferably with bleach or liquid chlorine. Your system isn't going to be able to produce enough chlorine to keep up with the UV degradation without CYA.

[aylad]

Inground vinyl pool. 28k gallons. 5 years old. Water clear, algae growing in some areas on liner/ladder/lights. Alkalinity and ph about normal. Salt system. CYA reads zero and free chlorine .5ppm. Inside of salt cell and pipe jets has rusty or black looking coating. Some rust stains on skimmers also. Is salt cell bad? Do I just need to add CYA? Already have had SWG on super chlorinate for 30 days and still only reading .5 ppm chlorine. Salt level at 3200ppm.
Thanks for any suggestion you may have.

I don't know the answers to all your questions, but I can tell you that you need to shock your pool and keep it at shock levels until the algae is dead, and that you'd be better off shocking with bleach instead of trying to shock with your SWG, especially with zero CYA. It won't wear your cell out as fast. Hopefully some of the SWG gurus will be by soon and can give you some better information. It will be helpful to them also if you can post numbers for alkalinity, pH, and calcium.

Janet

[bcrumb]

I took a sample to Leslie Pools today.
Free Chlorine-----0
Total Chlorine----0
ph---------------7.6
Alkalinity---------120
calcium----------210
CYA-------------10
Salt-------------3800
Salt digital readout is only 3000, seems inacurate for the first time ever!
The sample was taken in late afternoon on sunny day.
Leslie advised adding 4 lbs of CYA for starters. Started adding it to skimmers today. Probably should have bleached first, huh? Also Leslie said they recommend CYA at 80 on Salt Systems. I was under the impression from research here that 30 was more appropriate. Also the clipping device that seals the liner to the walk in steps has black algae(i guess) the full length of the crevace. Should I scrub this out or will the bleach shock take care of it? How much bleach do I need for 28000 gallons. I know the answer will be it depends on the CYA reading after adding the conditioner but still answer if you can. Thanks!

[aylad]

In 28000 gallons, 2 quarts of 6% bleach will raise your chlorine just over 1 ppm. With a CYA of 10, you need to get it up to 15 ppm and hold it there by testing and adding more bleach 2-3 times daily, or as often as possible. Keep an eye on your CYA level, as it will begin to rise within 2-3 days but probably won't top out for about a week. As your CYA level climbs, then your shock level for chlorine will, too--see the "Best Guess Chart" stickied at the chlorine forum for the proper chlorine levels.

As for CYA at 80, the salt systems need it this high for optimum chlorine production from the cell. On pools without salt systems, most people recommend the lower CYA levels.

Janet

[bcrumb]

Went home today and dumped 7.5 gallons of bleach slowly into the skimmers. Everyone at work with a pool thinks I am crazy. When I tested with a test strip for chlorine(before it mixed in well) the reading was over ten. Of course, 10 is the max the strip will read. I will check again tomorrow and maybe take 50/50 mix for higher range. Is this too much chlorine? How long do I need to maintain the "shock" level? Will the chlorine go away on its on or will I have to jetison water to return to normal?

BC

[cschnurr]

The amount of bleach you added should get you around 15ppm. I would measure with a test kit to find out where you are and not rely on strips.

You now need to monitor Cl 3 times a day keeping it at this level. As the Cl eats the algae, Cl is consumed and Cl level will drop until the algae is gone. You can tell when this has happened when there is no overnight drop in Cl. I maintain Cl at shock levels until I get 2 nights without an overnight drop.

You need to turn your SWG off to make sure it's not adding Cl overnight. I turn the SWG off and rely on only bleach while I'm shocking.

Whether or not your SWG is working I can't tell you, but the SWG cell has a life (#hrs of operation x %Output) and running it at superchlorinate is the same as 100% output. I use liquid Cl during shock so as not to use up my cell life and I don't know if it could generate enough Cl even if I wanted to.

My SWG manufacturer recommends CYA at 60-80ppm, check your SWG owners manual

[Spensar]

Went home today and dumped 7.5 gallons of bleach slowly into the skimmers. Everyone at work with a pool thinks I am crazy.

..........................Will the chlorine go away on its on or will I have to jetison water to return to normal?

BC

Just say your shocking with liquid (or pool) chlorine and don't use the word bleach, they will nod their heads in agreement that way. It's amazing how many people think bleach is stronger than "pool chlorine".

The chlorine will go away very quickly. It gets used up when it fights the algae, and in clear water it dissipates normally, especially on sunny days.