adjust cya before or after shocking

[Watermom]

lease test FC, CC, and pH add bleach if FC is below 15 and get a FC reading at dusk so we can see how we're doing at dawn.

Dave, she reports in her post above that her CC was 0 and she had no chlorine loss overnight.

Katey, if tomorrow morning you still show no more than a 1ppm drop and still no CC, then go ahead and let the cl drift down and you can bump up your CYA if you wish.

[Kateyru]

H2O Ma, you're back...so if I have more than a 1 ppm drop or more than .5 CC, I'll need to add bleach, right? Just trying to make sure I'll know how to proceed.

and do I turn SWG back on in the morning?

[Watermom]

Yes, If more than a 1ppm drop or CC greater than 0.5ppm, then you're not done and you'll need to add bleach. Otherwise, let the cl drift down. Keep your SWCG off until your cl drifts down. No reason to waste your cell life.

[Kateyru]

got it, thanks!

[BigDave]

If you have no more than 1 ppm FC loss overnight (with the SWCG off), your CC is at or near 0 and the water looks clear; you can let FC drift down. The complicating factor here is that we lost no FC last night but the SWCG was on so... we lost as much FC as the SWCG produced overnight.
If your FC is 14.5 or higher in the morning then we're done with the algae battle and you can let the FC drift down.
If you can't watch it tomorrow and your FC in the morning is 14.5 or below, add some bleach to get above 15 and turn on your SWCG. Run another FC / CC test when you get home and let's take it from there.

[Watermom]

Good catch, Dave. With the SWCG running, you can't tell if there was no chlorine loss overnight or if the SWCG made up the difference.

[Kateyru]

Yesterday morning (6 am) FC was 14 and CC = 0. I did not add bleach (sorry--too early and too much of a hurry to check Dave's post)). Pump is running 24/7 but SWG is still off. Test results this morning were FC = 10 and CC = 0. Water looks good. Do I need to add bleach and get back over 15 again?

[BigDave]

Not necessarily. Test FC tonight when the sun is off the pool, and again early tomorrow morning before the sun is on the pool.

If FC is the same or within 1 ppm then you're done!
If FC drops by 1+, we'll need to get back to shock level.

Do you still have a supply of dichlor?
Pump / filter on - SWCG off.
How's your filter pressure?

[Kateyru]

I have 3 1/4 lbs. of dichlor. Filter pressure remains steady. Do I need to leave pump on 24/7 till tomorrow am?

[BigDave]

Is filter pressure steady at the same pressure as clean or higher than clean but not high enough to backwash yet?
Let's leave the pump on.

[Kateyru]

pressure is same as clean

[BigDave]

Great! Looking forward to hearing that tomorrow morning's FC level is the same as tonight's.

[Kateyru]

fingers crossed...will email you in the am!

Morning! 7 am test results are FC = 7 and CC = 0. Pump is on but SWG is off. Let me know next steps.
Thanks!!
================
Just realized that I didn't give you results from late yesterday afternoon. They were FC = 8 and CC was <.5 but not quite 0.

[BigDave]

Sorry I didn't check in sooner, been busy - beautiful day.
So ... you're right on the edge. 1 ppm FC lost overnight and .5 ppm CC yesterday.
I'd backwash even if the pressure hasn't risen to get rid of the stuff that's been filtered out. I'd also do the evening and morning FC check again tonight - just to be sure.
Next, you need to decide how to raise your CYA. I presume you want to get it to 70-80 for your SWCG.
If you're willing, you can manually chlorinate with dichlor for a while - each pound of dichlor should raise your FC by 3 ppm and your CYA by 2.7 ppm and drop your pH by 0.11.
Or you can use CYA, each pound should raise your CYA by 5.4 and lower pH by 0.1 and turn your SWCG back on.
Let us know how you want to proceed and we'll be here to help.
What's your pH? you'll need to keep an eye on it as you raise the CYA.

[aylad]

I'd backwash even if the pressure hasn't risen to get rid of the stuff that's been filtered out.

Keep in mind that a dirty filter will filter better than a clean one--if the pool has been clear since the last backwash, there's really no reason to waste the water if your pressure isn't up...

Janet

[BigDave]

My concern here is that pool may have come down from shock a little early, we had 0.5 ppm CC yesterday and 1 ppm FC loss overnight. I'm thinking that the stuff in the filter is contributing to that 1 ppm FC loss.

[Kateyru]

Sunday 7 am test results were FC = 7 and CC = 0. I haven't backwashed today. If/when we are ready to increase the CYA--yes, I want to get to 70 - 80--I have dichlor and stabilizer/cya so can go either way. Before you suggested the dichlor, I was planning to use CYA. Dichlor has not been on my radar previously. Plus CYA seems more efficient based on the ratios you gave.
So, should I backwash first? then test cya, pH and TA at the same time then increase the cya then the TA then the pH???????

[BigDave]

FC was 7 this morning as well as yesterday morning? Is the SWCG on? The pool covered? Did you add chlorine? Was it really cloudy yesterday?
If your FC is holding overnight and you have no CC then ignore my suggestion about backwashing early - no need at all.
The dichlor adds both FC and CYA, If you're willing to manually dose the dichlor for a few days to keep your FC in range(SWCG off), you'll save a little of your cell life, get closer to your CYA goal and use up your supply of dichlor.
- or - if manually adding the dichlor sounds like a pain, turn on the SWCG, put some stabilizer in a sock(start with half of what you think you'll need) and hang it in front of a return.
Either way test FC an pH daily add Borax if pH drops. Keep FC above the minimum on Ben's Best Guess Chart (http://poolsolutions.com/gd/best-guess-swimming-pool-chlorine-chart.html). Remember: As you approach your CYA goal, your minimum FC will go from 3 to 5.
Give it a week before you test your CYA - no need to waste the reagent. The granular stabillizer disolves very slowly and you'll only be adding a portion of your CYA goal with each dose if you choose dichlor.
I wouldn't worry about the TA, 80 seems pretty good, lower TA helps reduce pH rise cause by SWCG use. If you find your pH too unstable, look around these forums for establishing a Borate buffer.
Let us know what you decide and how it's going.

[Kateyru]

FC was 7 this morning as well as yesterday morning? Is the SWCG on? The pool covered? Did you add chlorine? Was it really cloudy yesterday?
If your FC is holding overnight and you have no CC then ignore my suggestion about backwashing early - no need at all.
The dichlor adds both FC and CYA, If you're willing to manually dose the dichlor for a few days to keep your FC in range(SWCG off), you'll save a little of your cell life, get closer to your CYA goal and use up your supply of dichlor.
- or - if manually adding the dichlor sounds like a pain, turn on the SWCG, put some stabilizer in a sock(start with half of what you think you'll need) and hang it in front of a return.
Either way test FC an pH daily add Borax if pH drops. Keep FC above the minimum on Ben's Best Guess Chart (http://poolsolutions.com/gd/best-guess-swimming-pool-chlorine-chart.html). Remember: As you approach your CYA goal, your minimum FC will go from 3 to 5.
Give it a week before you test your CYA - no need to waste the reagent. The granular stabillizer disolves very slowly and you'll only be adding a portion of your CYA goal with each dose if you choose dichlor.
I wouldn't worry about the TA, 80 seems pretty good, lower TA helps reduce pH rise cause by SWCG use. If you find your pH too unstable, look around these forums for establishing a Borate buffer.
Let us know what you decide and how it's going.

[Kateyru]

Yes, FC = 7 yesterday morning and this morning. SWG is still off. Pool is not covered. I did not add chlorine but did add some salt. Yes, it was very cloudy yesterday (the explanation for unchanged FC of course).

Using dichlor is fine. The CYA (per K2006 test kit) is 30. It's going to take alot of dichlor, to go up 40ppm, isn't it?

CONFESSION: the TA = 80 may not be accurate as I have not tested it with K2006 kit. (Don't ask.) Do I need to test it now?

Do I need to keep filter/pump running 24/7 as I work with the CYA?

"Let you know how it's going" makes me laugh. You can't get rid of me this easily or quickly.
I LOVE my pool. Thanks for helping me become better at maintaining it.

[BigDave]

I'm sorry if that sounded dissmissive - not intentional.
As far as the pump, it depends. Are you planning to dose the dichlor into the skimmer and let it dissolve on top of the sand? How often and for how long do you run it on timer? Could you divide the run time into two or three periods a day?
When you have a chance run the FC CC pH and TA so we can see where we are.
Use up the dichlor you have on hand to maintain FC. When it's gone, put on the SWCG, wait a few days and test CYA then figure the plan to bring your CYA up to desired level using Granular CYA.

[Kateyru]

No apologies needed, you didn't sound dismissive...I just know I'll need a little more handholding.
I must have been testing while you were posting. Results are FC = 4.5 (sunny day), pH = 7.3, TA = 80 (bright pink color, I wouldn't call it red)
Dissolve on top of sand??? not sure what that means...dose the dichlor in the skimmer basket at the pump versus in skimmer at the pool? Wherever I put it, does all go in at one time?
I run the timer about 8 hours a day. It would be somewhat difficult to divide the run time for the next couple of days (due to work schedule).
re: sock for granular cya...a real sock or is there a pool sock?

[BigDave]

When the TA test changes (in one or two drops) from green to Red / intense pink you're there. 80 sounds pretty good.
I meant puttng it in the pool skimmer - it then goes through the pipe, through the pump then onto the sand. As far "as all at once" - slowly into the skimmer, you don't want a big chunk to clog your pipes or pump.
if you've only one run period a day, best to add the dichlor at the beginning of the pump run. I wouldn't pour it in the skimmer if the pump is not running and neither should you.
I've used a nylon stocking doubled over - some people use tube socks.
So... FC 4.5 on a sunny day - loss of 2.5 today. Another 2.5 puts you below your minimum. I'd dose with a pound of dichlor. You'll need to add Borax after that to lift pH.

[Kateyru]

Ok, I'll put in a lb. of dichlor 1st thing tomorrow morning then check FC and pH later in the day.
thanks.

[Kateyru]

I have a question. I'm at the point where I am adding CYA (granular) to pool water. It's in a stocking and hanging in front of a return as of late yesterday afternoon. Do I need to run the filter/pump 24/7 while CYA dissolves or just run the usual 8 hours? Btw, water is looking good, and FC = 5 and pH = 7.6 per most recent test.
Thanks.

[BigDave]

Hey, happy to hear from you, I'd been wondering how the algea battle finished up. Glad to hear it's looking good.
Run your pump on it's regular schedule. Give the sock a squeeze now and again to help it along.

[Kateyru]

Good, glad I can cut back on pump time, and I'll squeeze prn. Many thanks again for all the help!!

[Kateyru]

Well, I'm back with another question...I just tested (5:45 pm) and got FC = 11.5 and pH = 7.6 (holding steady). My FC is up from 5 in 48 hours. I added salt and may have gotten a little heavy-handed. Hayward recs 2700-3400 and I'm at 3900. I'd set SWG at 45%. Is the FC up because of too much salt or is % too high? Other thoughts?
Thanks.

[BigDave]

I don't know if extra salt makes extra chlorine - I doubt it, but if your chlorine is climbing, you may want to consider reducing the on time of the salt cell or the % on the salt cell.

[PoolDoc]

I just tested (5:45 pm) and got FC = 11.5 and pH = 7.6 (holding steady). My FC is up from 5 in 48 hours. I added salt and may have gotten a little heavy-handed. Hayward recs 2700-3400 and I'm at 3900. I'd set SWG at 45%. Is the FC up because of too much salt or is % too high? Other thoughts?

I don't think the salt is a problem. But, what is your CYA level, and how are you testing. I saw mention of an OTO kit; do you have a K2006 yet?

FC = 10+ is too high, if your CYA is below 40 ppm, unless you are having algae problems.

[Kateyru]

sorry to report that I am back with algae problems. My test results at 6:30 pm today were FC= 6, CC = .5, pH = 7.4 and TA = 70. I've been adding CYA through stocking since the time I thought I had previous algae problem resolved. I was out of town for a week but tested on 5/4 and pH was 7.6. I starting dosing again with CYA on 5/5. I'd turned my SWG on again when I thought algae problem was taken care of but FC had stayed high 11, 10, then 9 on 5/5 so I turned SWG off. So,without SWG, FC was coming down and was at 6 today. But now I have algae again): What caused it? Is it because I forgot to test pH and keep it at 7.5-7.6? Should I have left SWG on? Trying to figure out where I went wrong. Also, do I need to raise pH before I shock again? I plan to use bleach to shock.
Thanks.

[aylad]

If you have algae again, it's because you either 1) let the chlorine get too low, or 2) never killed it off completely before allowing your chlorine to come back down. It has nothing to do with your pH. Your pH is fine where it is--you just need to raise your chlorine back up to shock level (best to do that with bleach instead of your SWCG). How high shock level is depends on your current CYA level. Do you have the test kit yet so you can test your CYA?

[Kateyru]

The chlorine has not been below 6 in at least a month so I guess the algae wasn't completely dead...tho I tested and went back and forth with the forum experts till we thought it was.
So, I will test CYA in the morning then check pool calculator to find amount of bleach needed to shock then test and keep at shock levels and test and on and on. Does that sound right?
Thanks.

[Watermom]

Yes. That is the correct plan. Don't test CYA too often, though, or you'll waste the reagents. Did you get the K-2006 kit yet?

[BigDave]

You ( and Watermom of course ) are right. Is the algae in the water or on the walls and floor? Brushing the pool will help get the chlorine to the algae stuck on pool surfaces.
So, the recipie is:
Bring your FC up to shock level for your CYA and keep it there as best as you can by testing and dosing as often as you can.
Shut off the SWCG and run the pump 24/7.
Backwash the filter when pressure climbs 8-10psi over clean pressure.
Brush the pool, especially where algae is visible.
When you have less than 1 ppm FC loss overnight and minimal CC (less than 0.5 if using the 10ml sample size), keep the FC at shock for one more day.
Please use the "Edit your signature" link in Watermom's sig to add your pool's particulars to your signature.

Be patient.
Don't worry, you'll get this under control.
Keep us up to date.

[PoolDoc]

I scanned through this thread, and could not find a reported CYA level . . . .

[BigDave]

On 04-15-2012 at 05:02 PM on page 7 of this thread OP posted CYA of 30, since then has been adding CYA in a stocking.

[Kateyru]

CYA = 40 this morning so according to "Best Guess" I need to shock at FC = 15 and stay there or above.
Dave, algae is mostly on the bottom and lower sides of pool. Thanks for recapping the steps.
I'll edit signature.
Thanks!

[BigDave]

Do you still have the dichlor? You can use that to move toward your shock level and your CYA goal but remember as CYA goes up so does your FC goal for shock and normal operation.
How much dichlor do you have on hand?
Is there still CYA in the stocking?
Do you bleach / Liquid chlorine on hand? How much?

[Kateyru]

No more dichlor on hand. There is still CYA in stocking but I have removed it from the pool. I don't have any bleach on hand so was heading to the store. Should I use dichlor or bleach? I haven't done a cost analysis. If I use dichlor, do I need to raise pH to 7.6 before I start?

[BigDave]

Use bleach, it'll be eaiser, unless toting it around is an issue.

[PoolDoc]

CYA = 40 this morning so according to "Best Guess" I need to shock at FC = 15 and stay there or above.

Yes! And, brush all the algae spots AFTER adding a chlorine dose.

(Thanks, Dave!)

[Kateyru]

no problem toting bleach...easier than toting 40 lbs. bags of salt. yes, brush, brush, brush! My new mantra: Yes I can...defeat algae!!!
Thanks!

[aylad]

Your pH is fine where it is. Don't bother with adjusting it until it needs to be. If you get down to 7.0, then just adjust it up with Borax.

In a 22K gallon pool, 5.5 gallons of 6% bleach will get you up to 15 ppm. After that, each 1.5 quarts will raise your FC by 1 ppm, so you can use that as a guide. With your SWCG off, raise your chlorine to 15 ppm, (I would do this in the evening), then test in the morning and sometime during the day, adding whatever amount of bleach necessary to get back over the 15 ppm mark. Brush the pool daily, ( I would do this in conjuction with your bleach additions) so that you're knocking all the algae loose, getting better exposure to the chlorine. Hold that 15 ppm until you're not losing any chlorine from night time til in the morning, and then you can let it drift back down. Keep the pump running (but not the SWCG) and keep an eye on your filter pressure, so you can backwash it as needed (when the pressure rises 8-10 psi over your clean pressure).


This procedure is not difficult; but it does take persistence on your part to get it cleared up. If you don't fully get rid of the algae before you let the Cl levels come back down, or if you aren't consistent about maintaining your Cl levels, then you're going to be fighting algae all summer.

[Kateyru]

Okay, I think I've got it. Added 5.5 gallons of 6% bleach this evening then brushed all the sides and as much of the bottom as I could reach. SWG is off and pump set to run. I'm going to look back over the posts from my last attempt to shock and try to figure out where I went wrong. Maybe I didn't go long enough with FC at 15 and not losing any chlorine from pm till am.
Thanks.

[Kateyru]

It's clear to me now that I didn't keep FC at or above 15 (shock level) long enough even though I got to the point where I didn't lose more than 1 ppm and CC was < .5 from evening till morning. The FC was just too low to kill all algae. Once FC got down to 6, the algae was obvious. Thanks, Aylad.
Question for Aylad--why are the chlorine amounts you said are needed to shock different than what I calculated with the Pool Calculator?
Thanks.

[PoolDoc]

Question for Aylad--why are the chlorine amounts you said are needed to shock different than what I calculated with the Pool Calculator?

I'll answer that:

(1) The Poolcalculator is NOT ours, but it is based on Chem_Geek's chlorine spreadsheet, which laid out the analytical basis for my Best Guess chart, which was partly analytical, but partly based on my field experience.
(2) Both the calculator, and Chem_Geek's spreadsheet attempt to be EXACT. We don't, and not by accident. Pool volume calculations, test kit errors, and dosing errors all come together to make the sort of exactness suggested by those tools, unreachable in practice.
(3) So . . . we try to give estimated doses, that are calibrated to avoid problems. In practice, this means we estimate CHLORINE doses HIGH, and everything else LOW.

What Janet did was give you a dose for 15 ppm MORE chlorine -- in practice, that's the right thing to do, since she didn't know how much chlorine you'd have in your pool, when you added your dose. But, when you used the pool calculator, you probably took the chlorine level from your LAST test -- even though that value was unlikely to be correct by the time you added more chlorine -- and entered that into the calculator. So, the calculator told you how much MORE chlorine you should add to get there.

Mathematically, that's correct. But, practically that's wrong.

Richard (Chem_Geek) doesn't agree with me on this point. But, I think that's partly personal error. Richard is EXTREMELY careful and meticulous in his personal habits, and tends to assume others will be, too. He recently told me he'd NEVER had even a drip when using muriatic acid, as we discussed how we should tell people to add acid to pools. If anyone else had told me that, I'd assume they were exaggerating or outright lying. But, I'm pretty confident that he may be the only pool person who is that precise.

So, the pool calculator and his spread sheet work out for HIM, as exactly as they imply. Of course, if there's another pool owner in the USA as exacting and precise as he is, I'd be surprised.

My view is that the pool calculator is more exact in theory (apart from a few errors it has embedded), our approach is more correct in actual practice.

[Kateyru]

Thank you so much for taking the time to explain that. Makes perfect sense!

I kinda screwed up as I ran out of titrating reagent this morning BEFORE I could test. Should have been paying attention to that... I ran to the store and got distilled water to test that way. My best guesstimate using distilled water testing is that FC is at least 15. I actually did test FC before I added bleach last night so I could be fairly accurate with Pool Calculator calculations but then ended up adding a total of 5.5 gallons of 6% because that's what Janet said to do (and now I understand why). So, last night, FC should have been at about 21.5. All that to say that I think FC is at least 15 now. So, should I add more bleach now for insurance? If so, how much? Should I be testing pH when I test FC?
Thanks!!!

[aylad]

Leave the pH alone and don't worry about it. With the chlorine level that high, the pH result won't be accurate anyway, but if you're just using bleach, the pH is not going to change enough to be an issue. Focus on your chlorine and forget about the rest for awhile.

If you "add more bleach for insurance", then you may just be wasting bleach, so I wouldn't do that. Test your water again, estimate the level, then add bleach if you're under the 15 ppm mark. (And if you did get to 21 ppm last night, it won't hurt the pool--it would just be more available chlorine to work on the algae).

[Kateyru]

Ignore previous post as I think I am muddling through. Here's another related question. I reviewed the thread about my previous efforts to get rid of algae. Quick recap: in process of shocking, and after turning off SWG, FC test results were:

4/11/12, 5PM, FC =15.5
4/12/12, 6AM, FC =14
4/13/12, 7AM, FC =10
4/13/12, PM, FC = 8
4/14/12, AM, FC = 7
4/14/12, PM, FC = 7
4/15/12, AM, FC = 7
4/15/12, PM, FC = 4.5
4/16/12, PM, FC = 7.5
4/17/12, PM, FC = 9.5
4/18/12, PM, FC = 8
4/19/12, FC = 10.5
4/20/12, PM, FC = 8.5
4/21/12 PM, FC = 7
4/22/12, PM, FC = 4.5 (I turned SWG back on at this point)
4/23/12, PM, FC = 5 (I added 48 oz. of CYA, don't know if I added bleach)
4/25/12, PM, FC = 11.5 LEFT TOWN
5/4/12, PM, FC =10
5/5/12, PM, FC =9 (added 48 oz. of CYA)
5/6/12, Am, FC = 8
5/7/12, AM, FC = 6.5
5/7/12, PM, FC = 6
5/8/12 I"VE GOT ALGAE FOR SURE!
5/8/12, PM, FC = 6.5 and shocking starts

Also, re: test results, just fyi, when tested during shock period, CC was always .05, < .05, or 0.

As I said in previous post, it is clear to me now that I didn't keep FC > 15 long enough.
So, here's my thought/question:

**** 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 am not a chemist (obviously) and have never had much interest in chemistry but am somewhat fascinated by all of this.
An aside, it seems like there could be some really interesting science projects out of pool water study. I'll have to remember that when my grands are a little older :)