Shock or not?

douglee25

Well-known member
Apr 14, 2010
92
Philadelphia, PA
Here's the run down...

Pool - 23,000 gallons
SWG

Last Sunday pool was not 100% clear (just dull looking - I wouldn't say green by any means). I added some supplement bleach to bring FC up to 5 as I was traveling for four days and it's been 95+ degrees here for almost two weeks. The SWG I think is having a hard time keeping up because of the sun and heat. I turned up the SWG wide open for the 4 days I was would be gone.

On Sunday before I left - FC - 1.5, CC - 0.5, PH - 7.5, CYA 80


I returned on Thursday and I expected to find the FC much higher than 1.5 but it was still in fact only 1.5. CC - 0.5. When I looked in the deep end I noticed what appeared to be algae. I checked the baskets and they were full. I asked my better half if she had been taken care of the pool by emptying the baskets, etc and she responded no. Great! When I stood back I noticed the pool definitely wasn't super clear like in the past. It definitely had a green tint to it.

Fast forward - I thought I would just bring the FC back up to 5 and the filter would take care of the rest. I instructed the wife to add 1.4 gallons of 6% bleach but buy an additional 5 containers. Somehow a miscommunication happened and she added in all 6 (1.4 gallon) jugs. I found this out this morning when I went to test and the FC was not 5 but rather 23! The pool is currently blue green and somewhat cloudy. Initially I tested this morning at 10AM (FC - 23) I tested 4 hours later and the FC was 16. Wait a sec? Is there definitely algae in here that's consuming that much FC? I tested another hour later the FC was still 16. According to the cya chart, I should be up at 30 IF I was shocking. The CC is still 0.5.

The ultimate question is, should I be shocking or not? I have a party here on Sunday and I'm not sure if the pool is going to be ready or not.

Thoughts? Thanks again.

Doug
 

anonapersona

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Nov 5, 2008
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douglee25 said:
The pool is currently blue green and somewhat cloudy.

The ultimate question is, should I be shocking or not?

Doug
Yes, based on pool color and clarity and FC demand. I think the advice will be to use bleach and save the cell, it can't help you now it is more for maintaining.
 

dmanb2b

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Apr 4, 2009
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Yup...sounds like your going to have to raise FC up to 31 and hold it there until your done shocking...overnight FC loss test tonight would confirm the need, but given the signs you describe, you might as well get a head start...FC at 1.5 for that many days was too low. Sorry to bear bad news.
 

duraleigh

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A pool with visible algae should be shocked.

A pool that does not require shocking meets these criteria.......
1. Your pool water is sparkling
2. Your CC's are .5ppm or less
3. You can hold your FC overnight without losing more than 1ppm.
 

douglee25

Well-known member
Apr 14, 2010
92
Philadelphia, PA
Thanks.

I read that in the pool school, but I was confused because I seem to have criteria #2 and #3 met but yet the pool is not clear. I brought the FC up to 35 and I'll keep it there until it's clear.

Keep you all posted.

Doug
 

douglee25

Well-known member
Apr 14, 2010
92
Philadelphia, PA
OK - Held FC at 35 and it cleared in time for the party. I never got a chance to do a drop test but the pool was cystal clear and it had no CC's.

Question - Had about 10 people in the pool and with everyone in there, the pool turned cloudy as the day went on. While brushing before the party there was no cloudiness. I was thinking it's possible the paint was slightly coming off from everyone's feet. I did a drop test last night. Testing at 11PM and FC was 23. I woke up this morning and I tested again and FC was still 23 and 0.5 CC's but it was still cloudy.

So again - continue to shock or just let the filter do it's job?

Doug
 

douglee25

Well-known member
Apr 14, 2010
92
Philadelphia, PA
Ok, I let the FC come down and I've been testing it every night since 7/5. It's passed the FC drop test every night except last night. It was at 6.5 and now this morning it's 4 with 1CC. Up until this point I had either 0 or 0.5CC.

What goes? Now I need to shock all over again?

Doug
 

zea3

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Please post a current set of test results. What is your FC level when you are not shocking?
 

douglee25

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Apr 14, 2010
92
Philadelphia, PA
Full Test Results From Wednesday Night 7/7/10 (9PM) -

PH - 7.2
FC - 8
CC - 0
TA - 110
CH - 160
CYA - 80-90

Tested FC 7/9/10 at 6AM - 8 FC, 0.5 CC

Tested FC 7/9/10 at 9PM - 6.5 FC, 0.5 CC

Tested FC 7/10/10 at 6AM - 4 FC, 1 CC

I have been noticing the FC has been dropping and still the SWG seems as though it's been having a hard time keeping up. I have been trying to tune it in, but the FC is still dissipating. The pool is 23,000 gallons or so. I typically have been running 4-6 FC all season up until this algae incident.

Doug
 

zea3

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Yes bring the pool to shock level again. As for your cell, how old is it and has it been cleaned? There are people on here with more experience maintaining and troubleshooting the cell who will be along to give you more help in this area.

You have been targeting FC at the low end of the range for your pool. The recommendation from the pool calculator is 4-12. Try running the cell so the FC is at 12 and see if it will hold after you finish shocking.
 

douglee25

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Apr 14, 2010
92
Philadelphia, PA
I'm confused. According to the calculator, target 4 FC for SWG and 6-12 FC for non-SWG pool. The Chlorine/CYA chart calls for 4 FC minimum with a 6 FC target, so I thought I was in the correct range running the pool at 4-6 FC.

I don't know the age of the cell, but I have seen no calcium buildup on the plates. I even did a MA cleaning on Wednesday just for kicks.

Based on the Chlorine/CYA chart, I will bring up shock level to around 32 - 35 or so. This is getting ridiculous.

Doug
 

zea3

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I'm sorry you are correct. I misread the calculator. Something is off if 4-6 is not keeping the pool algae free. How long is your run time with the pump?
 

JasonLion

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Perhaps the algae has somewhere to hide out, and wasn't completely killed when you shocked last weekend. It would have to be a place with bad circulation. Algae sometimes grows in lighting niches, or inside a ladder, places with very bad circulation, and is protected enough that it isn't all killed when you shock the pool.

You need to shock again, and this time be extra careful to check and brush everywhere that algae could possibly be hiding, behind lights, the bottom of ladder steps, etc.

Cloudy water for a day or two after a pool party is completely normal. When lots of people are swimming, more organic debris gets into the pool than can be broken down and filtered out all at once. It often takes a day or two for the chlorine and the filter to catch up.

There is some chance there is something wrong with your SWG, but that seems very unlikely to me. Each time that FC has been falling below where it should be, there have been signs of algae. If the SWG wasn't working, the algae would have just taken over, instead of being relatively subtile in it's effects.
 

257WbyMag

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Feb 23, 2008
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The Chlorine CYA Chart states that most SWG pools appear to keep algae at bay with lower FC levels. Although this may work for most pools, most doesn't mean all pools and it would seem that yours is one that is an exception.

I see a couple of things that might be worth trying here. One is running your pump for longer than 8 hours. 8 hours just might not be getting it. Maybe it worked before but it has been really hot lately. I would suggest upping your run time to 12 hours and see if that makes a difference.

I would try shocking your pool again. Save your SWCG cell and use bleach and run the pump the entire time during the process until it is complete. No swim parties until the shocking is complete because the swimmer load puts stress on the water environment that you are trying to get clean. After this you are finished shocking (evidenced by 1 ppm or less FC loss overnight, 0.5 or less CC, and clear water), you should run a higher target FC than is recommended in the chart. 4 to 6 ppm may work for most SWCG pools, but it doesn't seem to be working for yours.
 

douglee25

Well-known member
Apr 14, 2010
92
Philadelphia, PA
JasonLion said:
Perhaps the algae has somewhere to hide out, and wasn't completely killed when you shocked last weekend. It would have to be a place with bad circulation. Algae sometimes grows in lighting niches, or inside a ladder, places with very bad circulation, and is protected enough that it isn't all killed when you shock the pool.

You need to shock again, and this time be extra careful to check and brush everywhere that algae could possibly be hiding, behind lights, the bottom of ladder steps, etc.

Cloudy water for a day or two after a pool party is completely normal. When lots of people are swimming, more organic debris gets into the pool than can be broken down and filtered out all at once. It often takes a day or two for the chlorine and the filter to catch up.

There is some chance there is something wrong with your SWG, but that seems very unlikely to me. Each time that FC has been falling below where it should be, there have been signs of algae. If the SWG wasn't working, the algae would have just taken over, instead of being relatively subtile in it's effects.
Good points. The railing is out of the pool and has been all season. There aren't any sharp 90 degree points in the pool. Everything has fairly sweeping lines that allow for easy brushing.

Once I get the pool back to less than 1 FC loss, I will run a test with the SWG running at night and measure the difference in the morning.

Doug
 

douglee25

Well-known member
Apr 14, 2010
92
Philadelphia, PA
257WbyMag said:
The Chlorine CYA Chart states that most SWG pools appear to keep algae at bay with lower FC levels. Although this may work for most pools, most doesn't mean all pools and it would seem that yours is one that is an exception.

I see a couple of things that might be worth trying here. One is running your pump for longer than 8 hours. 8 hours just might not be getting it. Maybe it worked before but it has been really hot lately. I would suggest upping your run time to 12 hours and see if that makes a difference.

I would try shocking your pool again. Save your SWCG cell and use bleach and run the pump the entire time during the process until it is complete. No swim parties until the shocking is complete because the swimmer load puts stress on the water environment that you are trying to get clean. After this you are finished shocking (evidenced by 1 ppm or less FC loss overnight, 0.5 or less CC, and clear water), you should run a higher target FC than is recommended in the chart. 4 to 6 ppm may work for most SWCG pools, but it doesn't seem to be working for yours.
I was running the pump 10 hours at the beginning of the season and I dialed it back to 8 and ran it this way for the past 6-8 weeks without issue. You have a good point as well that where I've been running FC it may not be high enough. Maybe I will shoot for 10 FC and 10 hours of pump run time.

I'll keep you all posted once I get this Dang thing back up to snuff.

Doug
 

duraleigh

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Doug,

1. Your pump should run 24/7 until your pool is clear....the thread has gotten confusing but I don't think your pool is clear.

2. You can only perform the overnight FC loss test if you turn OFF the SWG....Read how in pool school.

3. Because you are (I think) still experienceing an overnight FC loss of more than .5ppm, you have not finished shocking your pool.

Run your FC to 30 (Your CYA is still 80, right?) hold your FC at 30 until the pool is crystal clear, run your pump 24/7, backwash/clean your filter as needed.

Shocking and getting your pool crystal clear is all about killing and cleaning.....killing all theorganics in your pool (not done yet) and then cleaning up and filtering out the "carcasses".
 

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