Green Pool, How fast should FC Drop ?

[CyclingCraig]

Hi all

Opened the pool over the weekend:
20X40, 28,500 Gallon Vinyl pool.

Pool was the same green as my lawn, worst opening condition in my 3 years with this pool/house.

Started shock process after some vacuuming to waste, some draining to get CYA and then refill.

So my question is how fast should FC come down? Mine is not dropping as fast as I thought it would considering how green the pool is ?

Here are some numbersMonday night)(Tests with Taylor k-2006/TFTestKit)
FC = 6.5
PH = 7.6
TA = 80
CH = 85
CYA about 35.

With those readings I put in 2 lbs of Cal-Hypo (Low calcium anyway) to get FC back up to 12 - 14
Didn't get a chance to take reading this morning. Pool is green, I know I'm not doing an OFCL test so no real need to check, unless I had time to shock back up to 12 - 14 ppm which I didn't.
Anyway.....
Get home from work (took readings about 6pm) and my FC is still at 8ppm !! (Live in Central NJ and it hasn't been that sunny for past 2 days)
I was assuming my FC would be close to zero with how green my pool is by the time I got home? I would have thought my chlorine would be getting eaten up like crazy?

Pool is still green.

Added 1.25 gallons of 12.5% chlorine to bring FC back up to 12 - 14.

Shocking continues..

Thanks in advance
-Craig

 

[duraleigh]

Hey,

It's a mystery that may never be solved, some pools gobble chlorine at first, others seem to taste daintily of it like they are not sure they are even going to consume any.

Nevertheless, that answer to keep on keepin' on. You are doing the right thing with your chemistry and you will get your pool clear.....usually as quickly as anyone does, but just not using as much chlorine.....wish I knew.

 

[JamesW]

I have found that different algae consume chlorine at different rates. Mustard algae seems to be consistently slow to consume chlorine.

If the algae has any yellow, then it might be mustard algae. You might want to bump up the FC closer to mustard algae shock levels. Perhaps about 18 to 20 ppm FC.

 

[CyclingCraig]

Here are some updates. MORE confusion

So after I added my chlorine last night at about 6:30 pm, Let water circulate for a while and check my FC at about 8:30.

FC was at about 12.5 ~ 13 ppm.
CC was about 1.

OK Great, right?

So this morning I go down at 5:45 to take another reading.

FC = 12.5 !!!! WHAT??? (CC was about .5)... How could that be with a green swamp of a pool? Basically pass OFCL test??

Here is a "Possible" testing issue.. I'm using a 10ml sample of pool water for my tests and only using ONE dripper of the R-0870 DPD powder instead of two.
Could this be throwing off my FC test results? When I add the one dripper the sample turns very pink/red

I took JamesW's advice and put in another 3lbs of Cal-Hypo(73%). I will check FC later tonight when I get home from work.

 

[Bama Rambler]

Can you post a pic of the water as it is now?

 

[duraleigh]

Well, your pool is being consistent....it is consuming chlorine VERY slowly. Tonight, bump the FC up to around 16 and see if you can get a better consumption overnight. I can't explain why (and it makes no sense) but that seems to help getting my pool "off the fence" sometimes.

 

[CyclingCraig]

I'll try and upload a picture tonight when I get home from work

 

[JamesW]

Here is a "Possible" testing issue.. I'm using a 10ml sample of pool water for my tests and only using ONE dripper of the R-0870 DPD powder instead of two.

Use two good scoops of powder. I don't think that it would make too much difference, but it's better procedure, especially if the FC is high.

 

[CyclingCraig]

OK, things are starting to look much better

Reading as of 8PM last night: FC = 11.5ppm
I added about 1.25 Gal of 12.5% bleach
Let pool run for about an hour and took a reading at 9PM: FC = 18ppm

So now my pool seems to be actually using up the chlorine. Also I can see an improvement in clarity:

Added more 12.5% chlorine this morning to keep at high shock level. I know it will clear up, I just want it NOW !!

Last Night:
[attachment=1:foxnb989]IMG_2455.JPG[/attachment:foxnb989]

This Morning:
[attachment=0:foxnb989]IMG_2456.JPG[/attachment:foxnb989]

 

[Bama Rambler]

Oh yeah, that's better. I know you want it now but just keep after it and it'll come along soon.

 

[JamesW]

I think that it looks like possibly mustard algae is part of the algae.

Note: Many people disagree on what is, or isn't, mustard algae. Some people think that it is pretty rare. My opinion is that it is actually not all that unusual.

 

[CyclingCraig]

Thanks to all who helped me out.

This morning I could see the bottom drain on my deep end. Pool is pretty clear now, still have some ways to go thougth.

Still shocking at 18+ ppm in case it is mustard algae, I'm only loosing like 5 or 6 ppm of FC a day so it's not that bad to keep it that high.

Still need to keep my shocking up till I pass my first overnight free chlorine test. I hope to try one this weekend.

Thanks again and pool season is HERE !
-Craig