Is grren always algae?

Algae problems in swimming pool water.
Green (cloudy) water or slimy pool walls.
Black algae. Mustard algae. Pink or white pool mold.
chem geek
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Postby chem geek » Sun 01 Jul, 2007 21:11

Well, with your very high CYA level it's going to take a LOT of chlorine to kill the algae. You'll need to get the FC level close to 40 ppm and keep it there. Since you'll probably want to lower your CYA level anyway, you could just start doing a partial drain/refill -- vacuuming out the algae along the way. You should have at least some chlorine in the water even if not at shock level, but when the CYA is diluted to, say, 50 ppm, then you'll only need about 20 ppm FC to shock for the algae and will only need about 5 ppm FC to maintain to keep algae away.

Your hardness is already at 250 ppm so you'll have to watch the Calcium Hardness level when using Cal-Hypo. For every 1 ppm FC added with Cal-Hypo you also add 0.7 ppm CH. Bleach or chlorinating liquid would be a more pure source of chlorine.


Backglass
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Postby Backglass » Sun 01 Jul, 2007 21:13

vjpool wrote:Also, what's the difference between shock and chlorine? Not to sound silly, but I thought they were the same.


Shock isn't something you buy, it's something you do. You use chlorine to shock a pool....any kind. The bags you see called "shock" ARE for "shocking", but are just chlorine. It's marketing.
vjpool
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Postby vjpool » Mon 02 Jul, 2007 00:07

After the posts this morning, I switched back to Leslie's for a reading....here's what I have:

FAC-5
TAC-5
pH-7.6
TA-90
CYA-60
TDS-800
Copper/Iron-0

Quite different from the other reading. I don't know what the other store's clerk was reading, but I'm glad my common sense said "not to do anything they told me".

Can you help me from here? My pool is 16x32 inground gunite, @20,000 gallons and, still green; although I vaccuumed and backwashed but did not add any chlorine since the readings indicated were so high. I just want blue water again!

Thanks.
chem geek
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Postby chem geek » Mon 02 Jul, 2007 00:46

You really should get your own Taylor K-2006 test kit since I'm not sure whom you can really trust. The "5" chlorine level is suspicious because maybe Leslie's just used a DPD test that has a visual max of 5. If they used an actual colorimeter device, then perhaps the 5 is a real number.

With your own test kit, you will be able to measure the actual, real chlorine level frequently so as to maintain a high level during shocking. You can certainly add more chlorine assuming this latest pool store is correct, but please, please get your own test kit. Then shock with chlorine having the Free Chlorine (FC) up to 40% of the CYA level. Since knowing the CYA level is critical, your K-2006 test kit will give you that level (as well as chlorine and other parameters).

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