Been Shocking for two weeks and I still look green.

LBAyers

Member
Apr 3, 2010
5
Green Pool
This is my first summer with the pool. It had sat for two years without being open. It took me about a month or so earlier in the year to get it clear. Now it is getting hot and I cant use the pool because it is as green now as it was when I took the cover off (well almost).

I have kept the FC above 10 now for over two weeks straight with no signs of improvement. I am at a loss. I was under the impression that if you kept Chlorine in a pool that algae will not survive.

Can bleach not kill algae but still show FC on test readings? Because with my test I do not show the algae eating the chlorine and the pool is still green so the algae is not dieing.

I need some thoughts and advice please.

FC:22.5
TC:23.5
pH:7.8
TA:110
CH:140
CYA:30

My pool:24000 in-ground vinyl liner pool approximately 10 yrs old
Pool chemicals: BBB
My pump & filter:Haywood 1 hp pump and sand filter s 200


 

frustratedpoolmom

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May 20, 2007
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What are you testing with?

You stated you have kept the FC "above 10", are you confident in the CYA test result? And how often are you testing and adding bleach to maintain "above 10"? Are you reaching your shock target, and holding it there at all times, until the FC holds overnight?

Because if you are adding bleach sporadically and allowing the FC to drop back down in between, you won't make progress.

So I would think either your CYA test is higher than you think, and you aren't reaching shock level, or you aren't shocking often enough. you can test and add bleach as often as hourly.
 

duraleigh

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LB,

Welcome to the forum. :-D

As FPM said above, it's sounding like you may have some testing errors or have been letting your FC get too low....not keeping it constantly at shock level.

Let me reassure you....Chlorine kills algae and it will kill the algae in your pool if you hold it high enough and long enough. Have you read "How to shock your pool" up in Pool School?
 

woodyp

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Makes we wonder what the "average" shock time to clear a pool like that would be if you're doing everything right?
 

JasonLion

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Check your PH again when the FC level is lower, preferably when it is in the low teens. High FC levels can interfere with the PH test, so your PH might not be where you think that it is.

Doing an overnight FC loss test, as frustratedpoolmom suggested, will tell us a great deal. Algae doesn't always turn gray when it dies, sometimes it stays green. There is a small chance that the algae could all be dead and you are having filter problems.
 

JohnT

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Apr 4, 2007
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woodyp said:
Makes we wonder what the "average" shock time to clear a pool like that would be if you're doing everything right?
When my pump failed at the end of May, it was much greener than the OP pictures. I started my pump running about 7pm with no filtration. Added chlorine and stayed after it every hour or so until after midnight. Pool was blue with dead algae and clearing the next morning, got the filter working at lunch, swimmable clarity by late the next day, and only very slightly hazy three days later. Sparkling inside a week.
 

LBAyers

Member
Apr 3, 2010
5
JasonLion said:
Check your PH again when the FC level is lower, preferably when it is in the low teens. High FC levels can interfere with the PH test, so your PH might not be where you think that it is.

Doing an overnight FC loss test, as frustratedpoolmom suggested, will tell us a great deal. Algae doesn't always turn gray when it dies, sometimes it stays green. There is a small chance that the algae could all be dead and you are having filter problems.
I have yet to change out the sand in the filter so I think I might change it out this afternoon.

Also the PH test was done with the FC was at 7. So it should be accurate.

I am also testing with the TF-100 XL that was purchased in the spring. So I would asssume the only errors would be technician errors, LOL.

Also just to clarify the initial statement I have been shocking at MA levels for two weeks. The lowest FC level it has been in the week preceding that was 10.

My cause of concern is that overnight I am not losing FC much at all and losing some during the day but I attribute that to sunlight.

Thanks to everyone for your thoughts keep em coming.
 

chem geek

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Mar 28, 2007
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With not much FC loss overnight and with the persistent green, I wonder if it's from metals from the high pH from shocking. If you didn't start with a low pH of 7.2 or below, then adding yellow/mustard algae levels of chlorine would have the pH rise a lot so could cause coloring from metals in the water. For example, if you started with a pH of 7.5, then adding enough bleach to increase FC by 20 ppm would raise the pH to around 8.5. If you started with a pH of 7.2, on the other hand, the pH would rise to around 7.9 instead. This is why it is usually a good idea to first lower the pH when one is going to shock the pool with chlorine, especially at high FC levels.

If you can get a large enough sample of pool water in a white bucket such that you can see some of the color, then you could add acid to see if it lightens up. If it does, then it's likely to be discolored from metals.
 

LBAyers

Member
Apr 3, 2010
5
Well I finally got the pool clear again. The issue was that my chlorine drop test from the TF-100 XL was reading extremely high. Matter of fact I just tested my water again with it and it read that I had a FC reading of over 40. I know that is not accurate as it is closer to 8.

What do you think could cause my drop base test kit to start reading extremely high? I have only used Bleach and some pucks this season to keep it clean.
 

Bama Rambler

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Are you using the 10ml or the 25ml sample? That's a difference between .2 and .5 ppm per drop.
Is that 40 drops or 80 drops?
Are you on well water or public water? If you're on chlorinated public water, run the FC test on a 10ml sample of it. It should be in the neighborhood of 1 to 4 ppm.

Ok, I give up! I'm just not quick enough to beat FPM. :hammer:
 

LBAyers

Member
Apr 3, 2010
5
OK.....I am a total knucklehead. I appreciate the input you guys just figured out my problem. I was filling the drop test to 40 ml for some reason. Now all is well again.
 

LBAyers

Member
Apr 3, 2010
5
This would be why I let the algae situation get so out of hand a month ago. I don't know where I got fill it up to 40 ml and then test it.