Shocking details

Jump to latest Follow Reply
M

mokabb

0
Jun 10, 2009
60
Northern Philly Burbs
I am in the midst of shocking the pool. The CC has been 1 and the FC has been difficult to keep up using the TriChlor pucks. I am in the midst of changing to BBB.

I can give numbers later if they don't make sense.

When does one check the FC after the addition? minutes? hours?
 
Figure on checking 30-60 minutes after adding; pump on the whole time of course.

Trichlor is no good for shocking because it adds chlorine relatively slowly. Are you in the "use 'em up 'cause I already have 'em" mode? Stop using the pucks now and save them for when you go on vacation. What's your CYA level? (morbid curiosity)
--paulr
 
Sorry, I was tired and it was late.

I have stopped the trichlor after 3 summers of essentially no problems and started yesterday using bleach for FC and shocking due to the CYA issues. Pool is clear as a bell. No smell. Looks perfect. Yesterday morning, my numbers using FAS-DPD (Taylor) were:

temp 78
pH 7.0
TA 130
CYA 60-70
CH 350
FC .5
CC 1

I added some borax to try to get pH ~ 7.3 or so. I added some bleach to get me up to 5 ppm. Remeasured later in the day and it was 1. Added more bleach to get me to 6 and got up to 3.5. pH was ~ 7.3. I decided to shock.

Added enough bleach for a goal of 18, 2 hours later FC=9 and CC=1. Added bleach to get me to 20 ppm. Half hour later (when I posted) the FC was 11. When to bed frustrated.

Today, ~ 14 hours after last shock addition. Pool still crystal clear.

TA = 140
FC=1
CC=.5
pH= 7.0

:grrrr:

I'm about to go to pool store to see if they confirm my most recent numbers.

Is my CYA too high or is there some organic withcraft going on?

I'm about to pick up a S_ _ tload more bleach. And back to my day job.
 
sounds like organics. you can try an overnight fc loss test, but you're losing a ton, plus with a cc of 1 you need to shock anyway and that also indicates organics.. you're definitely adding the correct amount, right?
 
I'm using the amount recommended by the pool calculator.

I also had Leslie's check the numbers and they were pretty close to mine. Nothing glaringly different except they thought the TA was 90. It hasn't been that low since I bought the house 4 years ago. I had them test CYA and ammonia also - CYA 60, +3 ammonia.

I agree that it is likely the "organics". Shocking again soon.
 
Shocking is not a one-time addition of chlorine, nor is it necessarily a 2 or 3 day process. You need to keep your pool at shock level until 1) you can hold FC overnight (1pm loss is generally considered acceptible) and 2) you have <0.5ppm CC's.

By looking at your numbers, you never finished shocking; you got frustrated and quit, which I totally understand!!
Try again, and don't give up until your water meets the above two criteria!
 
Thanks for your input. I was tired last night more than I was frustrated though.

I am a bit frustrated because I have never really had to shock my pool like this over the past 3 seasons. I did the non-chlorine shock (toss in and forget) maybe 3 to 4 times during the season (excluding opening and closing) and used the trichlor pucks and occasionally had to add base to raise the pH. I usually would need a baskwash 1-2 times per season. The pool was always in good shape and I would add pucks and test ~ 1 weekly. Ran a Ray-Vac most of the time when I wasn't swimming. Obviously, this is a different problem than I have experienced. I could not keep the FC up.

I just had an espresso and am about to start at it again. Thanks for the encouragement.
 

Enjoying this content?

Support TFP with a donation.

Give Support
I got the 12% to start with, but then found I can get it for ~ 75% of the cost in the more dilute solution from a different store. I went for the cheaper - a side benefit is the increased exercise carrying it :) .

For those interested - I did get it up to shock levels ( >18) using the calculated amount this time. It started at 22.5 and drifted down to 18.5 after several hours. My aerator was on full steam at that point. I turned it off in case that increases FC losses. CC =.5 . I didn't bump it up and will retest in AM to see if it passes.
 
Fast forward 48 hours. Well, the overnight test wasn't even close. Since then I have been maintaining FC between 18-30, typically losing ~ 1 ppm every 1 hour. That is a WHOLE LOT a bleach. Still CC < or = .5. Water and pool has never looked better. SO, despite my filter pressure being ~2-3 above baseline, I backwashed. It was pretty brown yucky looking stuff. Like the Schuylkyll River after a huge rainstorm. Hopefully, that was the culprit. Bumped the FC back up to 22 ppm. I'll let you know.

Edit: Oh, BTW, the testing chemicals go quickly unless the sample is diluted.
 
The backwashing helped, but did not cure the problem. I lost only 3 ppm FC overnight, from 11 to 8. That's the best I've done by far. The CC is still essentially 0. The water is still crystal. The DE filter was disassembled and cleaned. There was still some old stuff caked in there. I now remember that I did not disassemble last fall when closing, like I had the prior 2 seasons. I just backwashed. Maybe that's the problem. I also read here that backwashing includes the "rinse" cycle. There is no mention of that in the instructions with the filter. :grrrr: Also. I measured my DE cup with an accurate scale. .75 lbs per cup instead of my instructed .5 lbs. I may have been overdosing the DE. So anyway...

I'll try another overnight test tonight and get ready for some more shocking if it doesn't pass.

Oh, does anyone get itchy hands after handling the DE? :?
 
I think that the CC held overnight at 20 ppm. Essentially no CC. Water clear. Getting TA down with acid addition and aeration over the past 24 hours. ( 150 to 110 now).

The troops are on the way. ~ 10 people or so. Ribs are cooking. Homemade wine, beer and sparking cider at the ready. They won't mind the high FC.

In the end, I am fairly certain that the "unclean" filter was the root of my evil. I will always do a full cleaning at fall closing ( or pool opening) and appropriately dose the DE, now that I have measured my DE "scoop" accurately.

In the future, it may be worthwhile recommending that posters consider a filter backwash or cleaning in a clear pool with a high chlorine demand.

Thanks again for the help everyone. Happy 4th for those who celebrate it! :cheers:
 
You must log in or register to reply here.
Thread Status
Hello , This thread has been inactive for over 60 days. New postings here are unlikely to be seen or responded to by other members. For better visibility, consider Starting A New Thread.
Top Bottom
Back
Jump to latest Follow Reply