Not sure what "shock" corresponds to regarding FC

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Positronic

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May 29, 2010
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Hi Jason,

I hooked up the pump and SWG to my above ground pool and have a lot of green algae. Water temp is 70%. My CYA is 50 (filtered), PH is 80+, FC is 12.5, and CC is .5.

Your article says to shock the pool but I'm not sure what "shock" corresponds to regarding FC? Is it keeping the FC at 15, or should I go higher as the CYA is 50? I know I'll need to lower the PH. I'll also need to add sand to the filter as I lost quite a bit when I emptied it out in the winter.

Btw - the SWG has a super chlorinate option and a dial that goes up to 100%. Last year it operated at about 10% to keep the FC at around 3. It can get the FC up pretty high if needed. As I only use the SWG about 4 months out of the year and remove it, I'm not concerned about using it up.
 
Looks like macgulley has given you the appropriate links :goodjob:

It is generally not recommended to use the SWG for shocking as it can not really add the FC quickly enough. You may find you should get up to shock level with bleach and then (since you do not mind) turn your SWG up to help hold the FC higher ...make sure you are testing the levels though as you want to stay in the shock range.

Also remember to turn OFF the SWG when you go to do the OCLT ... it would not be the first time someone found their FC went UP over night :-D
 
jblizzle said:
Looks like macgulley has given you the appropriate links :goodjob:

It is generally not recommended to use the SWG for shocking as it can not really add the FC quickly enough. You may find you should get up to shock level with bleach and then (since you do not mind) turn your SWG up to help hold the FC higher ...make sure you are testing the levels though as you want to stay in the shock range.

Also remember to turn OFF the SWG when you go to do the OCLT ... it would not be the first time someone found their FC went UP over night :-D
Click to expand...

The SWG is adding about 3.5 FC per day so assuming it holds I'll be at shock level on Friday (about 24 FC). It's not swimming weather here in Oregon yet so it's ok if it take longer than normal. The water is about 69 degrees and I need to get back in it and finish vacuuming the sides and bottom, brrrr. Seems amazing with all that green algae that the CC is still at or below .5. I guess algae doesn't add much to CC.
 
JasonLion said:
You will need to add chlorine manually. The SWG is not capable of adding chlorine quickly enough, and isn't all that likely to ever reach shock level.
Click to expand...

Actually FC hit 24 a day early with just the SWG. I turned it down and am fine tuning it to see what level keeps it at 24 (probably about 40 to 45% as 50% is raising the FC). Here are my notes..

5/6/12 – Opening pool, connected pump & saltinator, salt at 2700, added 1 bag.
5/7/12 – Got in pool (69) and cleaned, lots of algae, set chlorinator to super and output at 100, no CC present. FC about 12
5/8/12 – CC at .5, FC at 12.5, salt at 3100, PH at 8, CYA at 50
5/8/12 – evening, FC at 14.5 after super chlorinator on all day with output at 100%. Need to get it up to 24. PH at 8.2 about. Pool is still green, can’t see bottom though CC is .5 or less. TA is 125 (non-adjusterd for CYA). Added 12oz of PH reducer, supposed to drop it from 8.2 to 7.2…
5/9/12 – morning – FC at 17.5, super chlorinator & 100% output. PH at 8. Pool still green, can’t see bottom. CC still .5 or less. Added 16 oz of PH reducer.
5/10 – morning – FC @ 24, turned off super chlorinator & set output to 10%. PH at 8 still. Pool still green, CC @ .5 or less.
5/12 – FC @ 23.5, PH at 7.7, Pool still green, put in 60lbs of sand. Got in pool and vacuumed bottom though couldn’t see it. Strainer cup filled twice with debris. Set pool at 30%
5/13 – FC @ 22, PH at 7.7, Pool still green. Set SWG to 50%.. Vacuumed bottom some more. Strainer almost full of debris when done.
5/14 – FC @ 23, CC .5 or less, pool still green, can’t see bottom

Right now I have the SWG at 50% which is actually rising the FC slightly but now much. I'm fine tuning it to get it at 24. Had it at that but turned it down to far but am close to where it should be.

I was wondering if I had a flocculant (sp) if that'd help bind up the green dead debris for better filtering to clear up the water quicker, thoughts?
 
Re: Not sure what "shock" corresponds to regarding FC

You are not going to be able to fine tune it. As the pool clears the required FC will drop requiring you to reduce the percentage or run time.

Posted with Tapatalk ... sorry if I sound short ... hate typing on phone :)
 

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If the pool is still green, then the algae is not likely dead yet (usually the pool turns a cloudy white/blue when it is all dead). You have to maintain the shock FC level until everything is dead ... and you have CC<0.5, pass the OCLT, and the water is clear.

There is no need to add anything to the pool besides chlorine ... it will eventually clear.
 
In theory it might help, but it could also make matters worse while you are shocking. Flocc is typically used in conjunction with turning the pump off, stopping the movement of the water, cl, etc, while stopping filtering as well. While sometimes it can be used as a filter agent, I wouldn't bother.

If it is still green then the algae is likely still growing, and you still need to be in the shock phase.

Is the pump/filter running 24/7?

I myself have wanted a few times along the way to buy extra things to expedite the process. The most important aspect of pool maintenance IMO at this point is, patience, and of course frequent, accurate testing!
 
Yep pump / filter running 24 / 7. The water does look slightly less green tonight, more of a pale green now. The sand filter isn't really capturing the algae much as the water is almost clear when backwashing after a 24 hour period. Nice thing about the SWG, assuming it can keep the FC up at shock level (mine can), is that you only need to test once or twice a day as it keeps the levels consistant. Patience is pretty much key as I'm on day 8.
 
You SWCG may be able to keep up, but when shocking, we typically recommend turning the SWCG off and simply adding bleach manually. This saves wear on the cell and is the only way to really get a gauge on chlorine consumption. 8 days is a long time to need to shock a pool. When raising the FC to shock level and keeping it there, the process should only take a couple of days with good filtering.
 
Good points, the process would be shorter by the 3 days it took to get it to shock level. The pool had a lot of algae to start, very green. Right now the water is bluish with a slight greenish tint, still can't see bottom of deep end but can barely see bottom of shallow end. Last night I got in and vaccuumed and the bottom of the pool showed the color of the liner (blue) as I vacuumed, so it had a layer of debris on it. I then backwashed and the water was pretty much clear rather than showing really green water for awhile like it did earlier in the process. After the vacuuming I would have thought there would be more green in the backwash. Last week I added sand so I'm guessing the particles are too small to be filtered. I'm using #20 silica sand which is what is recommended.

The only time I've had to shock longer using gallons of bleach was converting from baquacil. FC is currently at 23.5. You can tell if chlorine consumption is less by whether FC keeps rising at the same setting. I now have the setting down to 20% which is close to the level it normally runs at to maintain shock level. True it uses the SWG cell more but that's ok as we only get 4 months out of the year to use it and the convience in time and money is worth it.
 
I may have a problem with the sand filter. When I started cleaning, the filter was low on sand as when I drained the water for winterizing it a bunch of sand came out. When I opened the pool I just ran it with low sand for a week or so. It worked as when I backwashed the water was dirty. I bought a bag of the #20 sand and dumped in about 50 to 60lbs on top the existing sand as it was less than a year old and put it back together. If it makes any difference, the sand at the bottom was a better grade (whitish color) and the sand I put in was the #20 silica sand.

The pool isn't clear and a few days after vacuuming debris settles on the floor and when I vacuum it up and I see the blue floor. After a bit of vacuuming I notice dirty water coming back in through the return. However when I backwash the water never has a sudden burst of dirty water, pretty much same clear color. So I'm thinking this long delay in clearing the pool up is due to the sand filter not filtering properly. When I put it back together I made sure the top went down inside the upright pipe. I let it go this long thinking the water was pretty clean and not much to filter out but pool water not clearing up much making me think I keep vacuuming the debris on the bottom which gets fed right back into the pool clouding it up. A few days later it settles and I repeat the process.

Any ideas what may be going on here?
 
Have you passed the first two criteria yet?

1. CC of less than 0.5 ppm.
2. FC loss of less than 1 ppm overnight with the swg off? See: http://www.troublefreepool.com/pool-school/overnight_fc_test

If not, focus on that first...i.e. keep your FC level above the 16 ppm (shock level for cya of 50 from poolcalculator.com).

If you have passed the two criteria above, post back and we can discuss some next steps, but these next steps require that you already pass 1 and 2 above and are only having problems passing 3: Your water is clear.
 
The hardest part is the patience.
Look at it this way: Your pool has an infection. A living organism infection. You are administering the medicine, chlorine. You need to maintain the proper dosage until ALL of the infection is dead. Dead, dead, DEE-EEE-AHE-DEE dead. (Did I spell that right?) When there is no longer anything alive infesting your water, no FC will be lost at night when there is no UV on the pool.
Everything else can hold off until the algae is dead. Hang with us, we do this all the time here. ;)
 
linen said:
Have you passed the first two criteria yet?

1. CC of less than 0.5 ppm.
2. FC loss of less than 1 ppm overnight with the swg off? See: http://www.troublefreepool.com/pool-school/overnight_fc_test

If not, focus on that first...i.e. keep your FC level above the 16 ppm (shock level for cya of 50 from poolcalculator.com).

If you have passed the two criteria above, post back and we can discuss some next steps, but these next steps require that you already pass 1 and 2 above and are only having problems passing 3: Your water is clear.
Click to expand...


CC has been less than .5 for quite some time. I haven't turned off the SWG so not sure about FC loss overnight. I used the Chlorine / CYA chart for SWG here .. pool-school/chlorine_cya_chart_shock .. which is why I've kept it at 24 though looks like 20 would have been better. What happens if you shock higher than recommended?

Regarding the sand filter, is there anything there I need to investigate as it is not backwashing any dirty water?
 
Positronic said:
CC has been less than .5 for quite some time. I haven't turned off the SWG so not sure about FC loss overnight.
Click to expand...
I think it is time for you to do the OCLT Again make sure you are above shock FC level and turn off the swg. This test must be done when the sun is off the pool.

Positronic said:
I used the Chlorine / CYA chart for SWG here .. pool-school/chlorine_cya_chart_shock .. which is why I've kept it at 24 though looks like 20 would have been better. What happens if you shock higher than recommended?
Click to expand...
The amount you are above is fine. In fact it is better to be a little above you FC shock level (for your cya level) then below to kill off organics in your pool. The guideline is that it is typically safe up to Mustard Algae level for pools and pool equipment. Since your cya is at 50 ppm use 20 ppm as your normal minimum algae shock level and 29 for your Mustard Algae shock level (got the MA level from poolcalculator.com).

Positronic said:
Regarding the sand filter, is there anything there I need to investigate as it is not backwashing any dirty water?
Click to expand...
Let's see how the OCLT goes first.
 

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