Fine Tuining

Shelley N

Well-known member
May 1, 2007
199
Denver, Colorado
#1
Okay, my 11,000 AG pool has been open and sparkling since April. I am a strict BBB fan. Here are my #s.

FC - 6
CC - 0
PH - 7.6-7.7
Alk - 130 red 140 brighter red
Cal - 70
Temp - 81

No matter what I seem to loose 1 to 1.5 ppm of chlorine over night. 9pm last night I had 7.5 chlorine. I have used Ben's kit for 2 years and do the FAS DPD and have never recorded any CC. Never had an algae bloom. Nothin'. This year I DO have a commercial construction site 3 houses away that has been in the dirt moving phase for months and half of it is ending up in the pool. Oh well, it's Colorado and the stuff is fine clay so I'm thinking it's practically as fine as DE so I'm vacuuming it up and using it as a super fine filter additive :-D

I'm watching the high CYA/Chlorine thread and would like to get to the point where I add 1 cup of chlorine every 2 weeks (HA), but there is the thing about measuring your chlorine loss over night to see how much you loose during the day to see where your pool as at...and I still loose chlorine over night!

Do you think I have been fighting something ever since owning the pool? I mentioned it is Colorado and we have a thinner atmosphere and are closer to the moon and stars, are they burning it? What is up?

I also am wondering if I should try to lower the alk or if I should wait for a problem.

Thanks all.
 

Poseidon

Well-known member
May 24, 2007
148
Houston, Texas, USA
#2
Shelly N,
The pool can use chlorine overnight without visible algae, especially with a heavy bather load. Remember, chlorine kills bacteria. Or it could be nascent algae. I don't think the night time stars are going to burn off chlorine, even in high Colorado :wink: How long has this been going on (wasn't that a song)? Anyway, your TA along with the other readings are ok for vinyl. What is your cya?
 

Poseidon

Well-known member
May 24, 2007
148
Houston, Texas, USA
#4
Shelley N said:
CYA is between 20 and 30.

What is nascent algae?

I don't think I've held the same chlorine over night for the 2 years I've had the pool.
That's algae that is just coming into existance, or trying to exist, but the chlorine is killing it the moment it "arrives". Strange that this would continue for that long though. Your posted chlorine level is certainly high enough to prevent problems.
 
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Shelley N

Shelley N

Well-known member
May 1, 2007
199
Denver, Colorado
#6
After extremely heavy usage last weekend I took it up to 10ppm Sunday night. To maintain after average use I usually add 3-4 qt at night every/every other night depending on how the OTO reads. No one has used the pool for a few days, so I was testing w/ the FAS DPD to see how much my pool uses when I noticed that it dropped over night.
 

Poseidon

Well-known member
May 24, 2007
148
Houston, Texas, USA
#7
Shelley N said:
After extremely heavy usage last weekend I took it up to 10ppm Sunday night. To maintain after average use I usually add 3-4 qt at night every/every other night depending on how the OTO reads. No one has used the pool for a few days, so I was testing w/ the FAS DPD to see how much my pool uses when I noticed that it dropped over night.
I have found, for me at least, that adding chlorine daily instead of every other day results in less chlorine useage overall. Seems that having too much chlorine leaves more of it unprotected by the cya, so it burns off quicker. This however has no bearing on chlorine usage overnight ....
At your 25 cya, you only need 3.0 ppm chlorine to prevent green algae blooms. Maybe actually lowering your chlorine level will result in less usage. My cya is 25 too, and I bring FC to 5.0 every evening. 24 hrs later it's 3.0 (maybe 3.5 on cloudy days). But mine probably doesn't get as much sun as yours. I dunno ... food for thought?
 

itabb

Well-known member
Jun 22, 2007
71
Atlanta, GA
#8
According to the Taylor test book, your ALK reading is based on the end color, which is when the color won't change anymore. So 140 is the correct number, at least according to Taylor.

I have a pool cover, and I'll lose more FC with the pool cover off than on overnight. I'm guessing it is due to organics falling into the water and more outgassing of chlorine with the cover off.
 
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Shelley N

Shelley N

Well-known member
May 1, 2007
199
Denver, Colorado
#9
Just tested at 8:30pm, and after a cloudy day with the solar cover on, the FAS DPD says we're at 5.5ppm. I'm guessing the high was mid 80s. That means I lost more last night than I did all day. hmmmmmm.
 

duraleigh

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Apr 1, 2007
31,397
Sebring, Florida
#10
hi, Shelley,

You either didn't post a CYA number or I missed it. I think it's time to shock the pool but need that number before we can decide just how much Cl to add.

Cl is consumed by either organics in the pool or the Sun........nothing else. You seem to have eliminated the Sun so the conclusion is pretty straightforward.

You seem to have a good grasp on your pool but, remember, shocking is not a one-time dose......it's holding your pool at shock level 'til you experience little, if any overnight Cl loss.
 
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Shelley N

Shelley N

Well-known member
May 1, 2007
199
Denver, Colorado
#11
Hi duraleigh. CYA is 20 to 30. Went from 5.5 last night to 5 this morning.

What if I don't shock, continue to add enough chlorine to get up to 6 nightly, and just enjoy the pool?

Shelley