adjust cya before or after shocking

[Kateyru]

Janet, we were posting at the same time. I remembered (in the middle of the night) that testing pH was moot point when shocking. I've been testing as best I can (as you suggest) and brushing.
You can see from my previous post, that I am not only focused on the chlorine, I am somewhat obsessing...

[aylad]

Once you get the algae killed off, you're going to need to raise your CYA levels to help protect your chlorine from the sun. When that happens, you're going to have to raise your chlorine levels to compensate for that. Look through this thread for some of the sigs that have the link for the "best guess chlorine chart", and that should answer your questions regarding higher chlorine levels.

In looking at your chlorine log, you simply did not sustain the chlorine levels long enough to kill the algae. As we've said many times throughout this thread, you need to get it to the 15 ppm make and keep it there until the algae is dead. By letting the chlorine levels yo-yo up and down like that, you may be preventing further algae growth, but you're not doing anything to kill the original bloom.

I don't really rely on CC readings for algae determination....sunlight and chlorine both help eliminate CC. I have personally seen algae on the side of my pool with a CC of zero. That's why a much more reliable test is to see no chlorine consumption overnight.

[Kateyru]

I was actually in the process of raising CYA level when the algae made itself known (to me) so I'm clear with that.
I do think I understand most of this now. In my previous shock attack, somehow the focus and comments back and forth got on FC loss from evening till morning coupled with minimal CC. The length of time my FC was at or above 15 ppm seems to have gotten overlooked it.
Many thanks again!

[BigDave]

**** Can algae, over time, raise its tolerance to FC? That is to say, if you don't get all the algae when you shock (due to human error or whatever), at some point in time after repeated unsuccessful attempts to shock, will the FC need to be maintained > 3 - 5 ppm in the future to keep algae at bay?I don't know if algae can become more cl tolerant through selection, makes some sense that you may be cultivating a cl resistant algea population. I do know that once you've raised the FC high enough for long enough to kill that population, you won't have to be concerned raising your base cl level for the resistant population as it will be gone. Any new algea that enters the pool will not have been through the selction process and will be no more cl tolerant than all the other algae.

[Kateyru]

Touching base again. I started my 2nd shock attack on 5/8 after messing up the first time, i.e., I didn't keep FC > 15 ppm long enough to kill all the algae. About the time I started 2nd attack, I ran out of reagent so used dilution testing until new reagent arrived. Using dilution testing then FC testing with K-2006 kit when replacement reagent arrived, I've tried to keep FC at or above 15. So, this is day 12. I was out of town for a couple of days this past week and am aware that FC got below 15 a couple of times. How much of a setback is that? I didn't lose any FC from last night until this morning. My plan, per forum guidance, is to stay at or above 15 for an extra day, that is, 1 full day after no chlorine loss overnight. That would be today if the 2 recent dips below 15 don't have a significant effect overall. Guidance please.
Thanks!

[Watermom]

You are right to give it the extra day as long as there is still no more than a 1ppm chlorine loss overnight from sundown to sunup and you don't have a CC reading.

[Kateyru]

FC was at 17 at 7:30 am. I added 3 qts. of bleach at that time since I knew I would be gone for a few hours. At 1:30 pm, FC was 15. I added another 3 qts. of bleach. At 4:30 pm, FC was 16. I was gone again for a few hours. I didn't add more bleach since it was 4:30 in the afternoon. Got home and checked FC again at 8:30 pm, and it was 13.5. I lost 2.5 ppm between 4:30 and 8:30 in the late afternoon/evening. Seems like a lot. I've added another 3 qts of bleach now (at 8:30 pm). That seemed the way to go rather than worrying about chlorine loss. Is this loss excessive for time of day? Sun sets about 7:30 pm and it's hot (mid 80's) but sun is off the pool by 5:30 pm or so. So, is the loss due to sunlight? Does stubborn, refuse-to-die algae exist???? I feel like I have been shocking for ages.
Thanks.

[PoolDoc]

Bleach loss during the day is likely sunlight. You can really only tell what your non-solar loss is, by comparing late PM to early AM readings.

What is your CYA level?

[Kateyru]

The last time I checked CYA was 5/8 and it was 40. I've been following Janet's recommendation to focus on FC and not worry about anything else. This morning at 6:30, FC was 16.5 and CC = 0. I had not been checking CC but did today since Watermom said to. I added 3 more qts of bleach and turned SWG on as I was not sure I could get home until late afternoon. Trying to make sure FC stays over 15.

[PoolDoc]

Do you still have visible algae?
Where? What does it look like?

Also, it's probably time to retest your CYA level.

[Kateyru]

No visible algae. Water looks good, nice and clear. I'll retest CYA this afternoon. Do you think I can let FC drift down or do I need to keep it at or above 15 for another day? Am really hoping for a clean pool by this weekend!
Thanks so much!

[Watermom]

Go with another day for added insurance. If after one more day, you still don't lose more than 1ppm overnight and still have CC of 0, let it drift down. But, be diligent about keeping your chlorine levels at appropriate levels based on your CYA reading. (Like Ben said, retest CYA to make sure you know what it is so you'll know needed cl levels.)

[Kateyru]

Okay, FC last night and this morning were the same and CC was 0. Doing insurance plan today :) If FC and CC are okay from tonight till tomorrow am, I'll let chlorine start the downward drift. CYA was 45 to 50 last night. I'm struggling with reading CYA and trying to accurately recognize "just till black dot disappears." I haven't had problems with chlorine levels in the past but plan to up CYA to 70 to 80 so will be more vigilant and diligent re: chlorine as needed.
thanks again for all the help. I just read "the history" of the forum. I am so glad the forum (and troublefree pools website) exist and very, very glad I found both!

[aylad]

Just don't ever let the chlorine get below 3 ppm, and if you up your CYA any more, then don't let it get below 5 ppm, and you shouldn't have any troubles.

The CYA test is a very subjective test--the best you can do is try to run the test in the same conditions (lighting, distance from tube to your eye, etc) so you can be as consistent as possible.

[Kateyru]

Glad to know it is very subjective test!

[Watermom]

It is definitely the hardest test to interpret.

[Kateyru]

Ah, you guys, I'm back again with green algae dust ): A quick recap of most recent battle with algae...from 5/21 to 5/24, FC was over 15 until afternoon of 5/23 when it dipped to 12.5 at 2:30 pm. CYA was at 45 during this period, fyi. I think that's when (on 5/23) we thought I'd won the battle, and I was letting FC drift down. Since then, the FC was below 7 only once on 5/28 and was at 5.5 when I turned SWG back on. On 5/29, FC was 7.5 and pH was 7.6. I turned SWG back off to get FC down to 5. This morning at 10:15 am (when I noticed green algae dust), FC = 5.5, CC = 0, pH = 7.6, Ak = 80 and CYA was about 65 as I started addingCYA again on 5/29 because I thought algae was long gone.
So, did I not keep FC over 15 long enough? How long is long enough? I think I had FC over 15 for a longer period than 5/21 to 5/23 but did not have reagent until 5/21 to know FC for sure. I know that I have to have FC at 20 now that CYA is up. Other thoughts???? Love my pool, hate the algae.

[chem geek]

Is your vinyl liner blue? If so, then I think you may have yellow/mustard algae and not green algae. Yellow+Blue(cyan) = Green. You describe the algae as "dust" which sounds more like yellow/mustard algae and would explain why the usual chlorine maintenance levels aren't keeping it away. Is the algae mostly on the wall and floor in the shady area of the pool? Yellow/mustard algae prefers shade. Do you have any removable ladders or other equipment in the pool where the algae might be hiding out inside? For plaster pools, we have people go behind light niches where they often find a lot of yellow/mustard algae if they have such an infestation, but I don't think you have pool lights (and therefore light niches) in your vinyl pool, do you? Is the algae in areas of poor water circulation?

Also, are you sure that it's algae and not pollen?

[Kateyru]

Yes, liner is blue. as i said on other thread, algae seems to disappear in the direct sun tho I think there is almost always a yellowish band of ??? algae (or a stain) where the wall and floor meet in several areas around the pool...if that makes sense. I have a ladder, not sure if it's removable as I've never tried to take it out. I have 1 pool light. How do I identify areas of poor water circulation? I'm fairly sure it's algae and not pollen.
Just read section on mustard algae, and I think you're absolutely right...that's the problem! No wonder my efforts were not enough. Sounds like a major production to get rid of mustard algae.
Many, many thanks!!!

[Kateyru]

Just realized that I posted a response on the other thread so left out some info here. CYA was about 65 on 5/30 so my shock level is now 20, correct? I'm going with the mustard algae theory so will shock at 20 till FC loss is < 1 ppm. Hoping that is done today (I was out of town all day yesterday and couldn't do much). When that's done, I'll move to super shock to get rid of mustard algae and will keep FC at or above 35 to 40 for 24 hours, correct? I've got to figure out how to get light out of pool. Can I put robotic cleaner and cloth bag, rubber mat (float) and nylon recliner floats in pool for 1 hour (in super shock) or is it better to clean with bleach solution? Also, instructions say to wash bathing suits. Do I need to use bleach with suits?

[Kateyru]

If I can't get light out of pool, is super shocking all for naught???

[Kateyru]

Help! On 5/30 at 9pm, I figured out that I had mustard algae...thanks to you guys and I went ahead and added several qts. of bleach that evening to start usual shock process planning to go to mustard shock after that, per website instructions. On 5/31 at 7:30 am, FC = 22.5 and I thought the CYA = 65 so I understood shock to be 20. I kept FC over 20 on 5/31 until I tested at 7:30 pm and FC was 16.5 I kept FC > 20 on 6/1 and lost 2.5 ppm of FC overnight and was at 19 at 7:30 am on 6/2. Got FB back over 20 on 6/2 but lost 2 ppm overnight so FC = 18.5 at 7:15 am on 6/3. Got FC > 20 all day on 6/3 but lost 2.5 ppm overnight again. This morning, at 6:30 am. FC = 22. I decided I needed to recheck CYA this morning, and it now looks to be 50. I had just added CYA (through sock) on 5/31 and got the higher reading.
So, does CYA settle down after being added? Why do I keep losing > 1 ppm of FC overnight? I was hoping to move to mustard shock today but guess I'm not done with regular shock yet. Please advise. Thanks!

[BigDave]

CYA doesn't settle, you usually lose it by splashout or backwash. A drop of 65 to 50 may just be the accuracy of the test.

[CarlD]

CYA doesn't settle, you usually lose it by splashout or backwash. A drop of 65 to 50 may just be the accuracy of the test.

In other words, by dilution. But try to always run the CYA test the same way. One trick I use is to pour it back into the squeeze bottle and run it again (it doesn't change the solution to do this). Sometimes I do it three times, always trying to do it the same way. This helps me neutralize errors in any one of the readings, and I'm not using any more reagent, just reusing the sample.

[PoolDoc]

Katey,

This thread has gotten VERY long and hard to keep up with. Could you please enter your pool info here:

Pool Chart Entry Form (http://goo.gl/cNPUO)
Pool Chart Results (http://goo.gl/PXaLu)

. . . and log your test results, here:

Pool History Entry Form (https://docs.google.com/spreadsheet/viewform?formkey=dHR6ZXlwVGY3ZGpkODZ0MThGWl9nYnc6M A)
Pool History Logsheet (https://docs.google.com/spreadsheet/ccc?key=0Ahjo2iDF0aJgdHR6ZXlwVGY3ZGpkODZ0MThGWl9nY nc)

That would make it MUCH easier to keep up with what's going on, and give an intelligent response. I'm going to go back and put in the first couple of test results you have, but if you'd do the rest, and any new ones. The short URL for your test results is http://goo.gl/6ok5j and I'm adding that to your signature.

Thanks!

[Kateyru]

I'll have to do this later/this evening as I'm at work today. thanks.

[PoolDoc]

I entered everything except today's.

If you would, test EVERYTHING except CYA, and post complete test results INCLUDING calcium hardness, but using the CYA levels you got earlier today. Also record salt and filter info.

[Kateyru]

I just tested and added results except for cya. tried to go back and add results from yesterday but couldn't. I turned on SWCG this am at 50% awaiting mustard algae shock guidance. Looks like I need to lower TA but will wait to hear from you.
Appreciate the CYA testing tip!
Thanks.