fighting mustard algae

[Kateyru]

I'm starting a new thread as my old, long one seems to have gotten lost in the shuffle.
I'm pretty sure I have mustard algae, thanks to info from you guys. My most recent test results were on 6/5 as follows:
FC =17, CC = 0, pH = 7.6, TA = 90, salt = 3400. A problem is the CYA. I thought that CYA = 65 on 5/30 but tested again on 6/4 and got 50. Test results per K-2006. About the FC = 17, I was in the process of shocking so I could do mustard algae shock.
On 6/5, I added muriatic acid (per Pool Calculator specs) to lower pH to 7.2.
On 6/6 in the AM, overnight FC loss was < 1 ppm and CC = 0 so I started mustard algae shock treatment. FC that morning was 27.5 and I added 21 qts of bleach to add 14 ppm so I would be at 48.5 ppm (over mustard algae shock level) AND turned on SWG as I had to be gone all day. At 7 pm, I turned SWG off and tested FC = 31. I added bleach = 8 ppm.
On 6/7 early am test results were FC = 37. I added bleach = 12 ppm and turned SWG on again as I was gone most of the day again. At 12:30 pm, FC = 35.5 and I added bleach = 2 ppm. At 7:15 pm, FC = 29.5. I turned SWG off and added bleach = 16 ppm.
I have brushed walls, sides, ladder, etc, ever time I've added bleach.
I have not been able to keep FC at or above mustard algae shock level for 24 consecutive hours so far. Tomorrow (Fri, 6/8) I can be at home all day if needed. Please advise.
thanks.
Am I way off track on this?

[Kateyru]

Correction for last addition of bleach, it was 14 ppm. Estimate FC was then 43.5 This morning at 6:30, FC = 36.5. Big drop! Added bleach = +6 ppm so estimate FC = 42.5.

[chem geek]

The last I recall from the other thread is that you have a light in the pool but didn't remove it to get into the light niche. There may very well be a lot of yellow/mustard algae lurking there which means that even if you kill it off in the bulk pool, it will re-introduce itself as soon as the chlorine level drops down below around 15% of the CYA level. It's one of those choices you have to make -- either find and kill the last of the yellow/mustard algae in all dark places it hangs out in the pool or deal with having to inhibit it with one or more of 1) a higher than normal FC that is 15% of the CYA level or 2) use an algicide (such as Polyquat 60 weekly) or phosphate remover at extra cost.

[Kateyru]

Thanks, very helpful. I'm glad to have options tho there is a definite best (get the darn light out). One more question...if we can get the light out after FC is much lower and we can try to remove while we are in the pool, I'm guessing that I would have to do the mustard algae shock treatment all over again, correct?

Also, based on additional reading, I think the stuff I see around the bottom edges of the pool is probably stains rather than mustard algae.

Many thanks again!

[BigDave]

You probably can get in the pool (CYA 50+ppm FC 30+ppm). Wear an old suit(you don't care about), cover your hair, work quick, take a shower. maybe better than letting it drop, doing the work and then starting again. Your choice.

[Kateyru]

I didn't remember correctly about the light. My husband got in the pool before I started shocking. The screw was so rusted that he was afraid it would break off and cause more serious problems. any suggestions about that?
I'd also thought I get our pool guy to try to remove the light as he likely has more experience....tho a service call is $75.
Thanks!

[Kateyru]

Update: Pool guy wasn't willing to try to remove pool light. Hope no lurking algae back there but time will tell. I removed the treads on ladder the other day while still shocking.

I'm now letting FC drift down. Water looks great, very clear. FC = 7.5 this morning. On Thursday, CYA wasn't showing up when tested (not sure what happened) so I added 3 lbs. through a sock. That being 1/2 the amount needed to get CYA to 70. I am leaving town in the morning for 2 weeks. So, I won't get an accurate read on CYA until next Thursday???? What do you suggest about adding more CYA? I'm checking FC and pH daily.
Thanks.

[aylad]

If you're planning to run your SWCG, you need to add whatever amount of CYA the manual for your unit calls for, and that' usually around 80 ppm. If you are not running your SWCG, do you have somebody to take care of the pool while you're gone for 2 weeks, so you don't have to start over when you get back?

[Kateyru]

Yes, I'll run SWG on regular schedule. My manual says CYA should be 60 to 80. So I should go ahead and add enough CYA NOW to get to 80 ppm? My husband will be at home but he is not overly helpful with the pool. If I go ahead and add CYA, the FC and pH should be tested everyday for several days? Hope I can convince him (the husband) to test...
Thanks.

[aylad]

Yes, go ahead and add whatever amount you need for your SWCG. The FC will definitely need to be tested (and adjusted if necessary) on a daily basis. The pH should be okay if he tests it every few days....

[Kateyru]

Thanks!

[Kateyru]

Hi Guys, I'm back home and pool looks good...not visible algae but high FC may be compensating. So, here are current results:
FC = 10.5
pH = 7.7
CYA = 50
TA = 90
I know that CYA needs to be higher. Do I lower pH and TA first or raise CYA?
SWG was running at 65% so have turned it down to 35% to lower FC. In the past, running it at 50% has kept FC steady.
Thanks!!!!

[aylad]

Leave pH and TA alone and add CYA.

Janet

[Kateyru]

Thanks so much!
Happy 4th!!!!!!!!!!

[BigDave]

I wouldn't drop the pH just yet, let it get closer to 8.0. When you do lower it, bring it down to 7.5/7.6. This will drop your TA. When the SWCG brings it back near 8.0, lower it again. You will be performing the TA reducing procedure but slowly.

Go ahead and bring up the CYA and good luck with the yellow algae.

[aylad]

Uhh, I just said that!! :)

Janet

[BigDave]

Yep, sorry. Me post real slow. OTOH I'm glad we're saying the same thing

[Kateyru]

Hi again,
I added CYA on 7/6. FC = 8 on 7/6 at 6:30 am and FC = 7 this morning and SWG has been off since yesterday morning. Slow drop with sufficient CYA, huh?
My pH = 7.7 today. I'm trying to let FC drift down to 5. Should I work on pH yet?
Mustard algae is still gone...yea!!!
Thank you, thank you!!

[aylad]

I wouldn't drop the pH just yet, let it get closer to 8.0. When you do lower it, bring it down to 7.5/7.6. This will drop your TA. When the SWCG brings it back near 8.0, lower it again. You will be performing the TA reducing procedure but slowly.

.

[Kateyru]

Hi Team,
I'm back again...after being gone for 3 weeks. A 2-week vacation, 1 week at home and another 3-week vacation is great for me but not so good for the pool.

test results on 7/4 were as follows:

FC = 10.5
pH = 7.7
CYA = 50
TA = 90
I added stabilizer before I left town trying to get level to 70. I asked husband to check FC and pH daily and to let me know if FC got to 5 and when pH got to 7.8 so he could add acid to lower and get TA down. He says that he checked every few days and FC never got down to 5 and pH never got up to 7.8. He only added salt while I was gone. We had lots of rain and high temps of 100 for many days.

Test results yesterday:
FC = 8
pH = 8
TA = 48
CYA = 60 to 70
and, natch, I have algae again.

I am now shocking again (at 20 since CYA is 60-70).

What made TA go down like that...rain, debris in pool????

FC stayed high (somewhere between 7 and 8) so what made algae return? pH too high?

After I shock, what is next step? Raise TA? Raise CYA?

Thanks.

[BigDave]

Mustard algae? I don't think you ever killed it all. You'll need to take the FC way higher than 20 and keep it there for a long time and brush everywhere it might hide. Please don't raise your CYA at this point.

[Kateyru]

I really thought I'd gotten it...the last test results before I left town were taken on 7/10 rather than the 7/4 results I posted in yesterday's post. On 7/10 results were:
FC = 5
pH = 7.8
CYA = 60-70
TA = 90
and the water looked great. Previously, the algae would show up when FC got down to 8.
Sigh...I'll do the mustard algae shock routine...regular shock till FC loss is less than 1ppm overnight then move to mustard algae shock levels.
Thanks.

[BigDave]

As I recall, you weren't able to open the light niche. It could be lurking in there. I believe ChemGeek advised that you'll need to keep FC above 15% of CYA to keep the yellow algae at bay if you can't get rid of it all.

[Watermom]

No need to do 'regular' shocking and then move to 'mustard algae' shock levels. Just start with the higher shock levels.

[Kateyru]

Will do! I just reviewed "mustard algae" section on TFP website. Rec is to lower pH before shocking. Do I need to do that or just shock at higher level for mustard algae? I need to maintain mustard algae shock level for 24 hours, correct?
Thanks.

[chem geek]

The pH rises when you increase the FC levels and for yellow/mustard algae you raise the FC A LOT. Lowering the pH first helps to lessen how far the pH rises and has the active chlorine level be higher as well. Ironically, having CYA in the water has the pH go even higher when you add chlorine compared to no CYA. For example, using a TA of 80, CYA of 70 ppm I get the following pH changes from raising the FC by the amounts indicated when using a hypochlorite source of chlorine.

Regular Shocking (from 5 ppm to 28 ppm FC so increasing 23 ppm FC)
pH goes from 7.5 to 8.7 (active chlorine 0.21)
pH goes from 7.2 to 8.2 (active chlorine 0.26)
pH goes from 7.1 to 7.9 (active chlorine 0.28)
pH goes from 7.0 to 7.5 (active chlorine 0.31)

Yellow/Mustard Shocking (from 5 ppm to 42 ppm FC so increasing 37 ppm FC)
pH goes from 7.5 to 9.0 (active chlorine 0.35)
pH goes from 7.2 to 8.7 (active chlorine 0.45)
pH goes from 7.1 to 8.5 (active chlorine 0.51)
pH goes from 7.0 to 8.3 (active chlorine 0.59)

The pH should drop back down at least part of the way as the FC drops, but during the shock treatment it would be better to not have the pH rise quite so much. Note that the main reason for the higher shock level is to get the level higher even in areas of poor circulation and to kill algae that has been established so has more protective layers (or is thicker). Technically, if you were able to access the algae wherever it hides and break it up, it wouldn't take so high a chlorine level.

If there were no CYA in the water, then adding 37 ppm FC with a starting pH of 7.5 would go to a pH of 8.0 instead of 9.0 shown above. Of course, with no CYA in the water one wouldn't need to shock so high (but chlorine would break down from sunlight quickly).

As for the advice about going to a regular shock level first, that's for pools that have a mixture of algae problems or where the overnight chlorine demand is high. The regular shock level gets rid of any green algae and chlorine demand without losing so much during the day from sunlight. After that stage, then shocking at the higher yellow/mustard alage level is done. In your case, you don't have other problems or chlorine demand so can start off right with the higher yellow/mustard algae shock level. This is the problem with trying to codify these sorts of things into rules -- there are too many unique situations to have a "one instruction for everyone" so posted instructions need to be seen more as guidelines while the forum experts can guide more specifically. Nevertheless, Ben's instructions are very thorough and work well in most cases; the TFP ones tend to be shorter and simpler and hence have more exceptions. Also, some things I've recommended (such as lowering the pH before shocking) don't get into such rules.

[Kateyru]

I'm a little confused about...
1) whether I should lower the pH now. Most recent test results on 7/31 before I started shocking:
FC = 8
pH = 8
TA = 48
CYA = 60 to 70

At this point, I'm only testing FC as I know that pH test won't be accurate. So, should I lower pH based on it being 8 (before shocking)?

2) what is mustard algae shock level for CYA of 60 to 70? 35 to 40 ppm per TFP chart or 42 per your message? How long do I maintain that level?
Thanks.

[chem geek]

Yes I would lower the pH now. From what we have more recently learned, the pH test is actually not inaccurate at first even at higher FC levels when there is CYA in the water. At high FC what you will find with the pH test is that it initially gives the correct reading and then over about a minute or so it turns the purple color caused by the high FC oxidizing the indicator dye. Apparently, the lower active chlorine level from the presence of CYA slows down the rate of the FC interference in the pH test. So your pH reading of 8 is likely correct and you should lower the pH quite a bit (at least to 7.2 if not 7.0) before shocking.

As for the yellow/mustard algae shock level, you don't have to be exact about this. 35-40 ppm FC is fine. It isn't like there's a magic number where it works -- higher just goes faster.

[Kateyru]

pH = 8 was before I started shocking...which I'm doing now. I'll add acid to lower pH now.
I'm such a "rule-follower" that I try very hard to do exactly the right number...glad to know it's not that exact. How long do I maintain mustard algae shock level?
Final, for now, question...previously you said that I could either keep FC at 15% of CYA, use polyquat 60 weekly or use phosphorus cleaner weekly re: mustard algae (and possibility/likelihood of not getting rid of all of it since I couldn't remove my light and clean the niche). Will any of those options actually get rid of the mustard algae or just keep it out of sight?
Thanks so much!!!

a few minutes later...
Hmmmmm...I just tested FC. This am at 7, FC = 41.5. I had to be away most of the day so turned SWG on at 50%. Just tested at 4:15 pm, and FC = 23.5. Quite a drop, considering SWG was running. So, do I start all over re: shocking? Just added acid to lower pH. How long before I add bleach?

[chem geek]

The chlorine will drop during the day. What's more important is how much it is dropping at night. Just add more chlorine to raise the FC again. Shocking is a process, not a one-time dose. You'll maintain the shock level until all the visible yellow/mustard algae is gone and your overnight chlorine loss is normal (usually < 1 ppm FC but at the higher shock level it might be OK to be a little higher than that) and then to be sure you'll keep it at shock level for another day or two.

As for those other methods of maintenance with higher FC or polyquat, etc., those may not be necessary. Let's see if we can completely get rid of this so you won't have to use other maintenance methods. Those methods just keep any yellow/mustard algae in check and they don't completely get rid of it.

[Kateyru]

Ok, I think I've got the plan. Shock at higher levels till no visible algae and overnight chlorine loss is normal...just like regular shock process.
I wasn't sure it was possible to get rid of all the mustard algae since I can't get pool light out.
I think this will take awhile and lots of bleach. I added 4 jugs of bleach (182 oz. jugs) last night to get FC = 40. This morning at 8:30, FC = 33.
Off to Dollar General (best price on bleach there and at Costco, btw) to get lots of bleach...should have bought stock :)
Important question, would you swim in this, FC = 40? It is hot as hades in Alabama!!
Thanks so much!!!!!!!

[Kateyru]

At 12:30 pm, FC = 37 so I added 2 more jugs (182oz. each) of bleach then measured pH. I added 50 oz. of acid last night based on pH of 8 BEFORE I started mustard algae shock. The pH is currently over 8. Do I add more acid?
Thanks.

[PoolDoc]

You need to keep your chlorine high -- I haven't re-read the thread, so I don't know how high -- but you ALSO need to keep your pH in range. Add some acid, until it's below 7.8!

[Kateyru]

Okay. What about TA which was 48 on 7/31?
Thanks.

[PoolDoc]

TA is related to pH, but not the same: you can have hi TA and low pH, hi TA and hi pH, lo TA and lo pH, and lo TA and hi pH!

You need to lower your pH! Once you do, you need to re-test your TA. If your TA is excessively low, you'll need to add bicarbonate, and THEN probably lower pH some again.

[Kateyru]

I added muriatic acid when I was at home for lunch. Will re-check pH this afternoon and get it down < 7.8 then test TA. I'm continuing to shock at mustard algae level. Pool water seems to have gotten way out of whack...
thanks much!

[PoolDoc]

Did you sign up for the Pool Log? (I haven't matched email addresses with user names yet -- we'll do that in the next few days, and set up all the forms and spreadsheets.)

If not, you need to do so. (Did you get an email about it?)

[Kateyru]

Is the Log the same as Pool Chart Entry and Results forms or Pool History entry or logsheet? If so, those were set up and have some info. I will update if that's where my info needs to be. I have not received an email about the log.
thanks.

[Kateyru]

Help!!!!!!! I added 20 oz acid at 12:30 today to lower ph. Tested again at 5 and added another 6 oz. Per Pool Calculator, this should get my pH to 7.6. I was heading to store for more bleach (for mustard algae shock) and decided to test TA so I could pick up some baking soda too. I thought my TA was 48 on 7/31. I just tested (6pm) and TA is basically off the chart on the high side. I used K-2006 kit and tried using the regular test of filling tube to 25 ml. I quickly realized that I was putting in too many drops trying to turn water red so started off and used 10 ml sample. I quit after adding 22 drops of R-0009 and still hadn't turned sample red...it was green, then blue, then yellow and heading darker/to red but, YIKES, that is some high TA.
Do I lower pH to 7.2 and aerate pH to 7.6 then lower again???????

[PoolDoc]

I quit after adding 22 drops of R-0009 and still hadn't turned sample red...it was green, then blue, then yellow and heading darker/to red but, YIKES, that is some high TA.

Watch this video, and retest: http://www.youtube.com/watch?v=gmpS--VsNrY&feature=youtu.be

The rest of the videos are here: http://www.poolforum.com/pf2/showthread.php?17157

[Kateyru]

THANKS!!!! That was really weirding me out!!!

[Kateyru]

Hi Team,
An update and questions...test results from earlier this morning are:
pH = 7.2
TA = 90
CYA = 35
FC has been drifting down since mustard algae shock attack. My estimate of FC is 15. I had to use dilution test as I am out of reagent to use with K-2206 test.

Questions:
1) is there a way/procedure to use fewer drops of R-0871 when repeatedly testing FC at mustard algae shock levels?
2) should I continue to lower TA (by adding acid to lower pH then aerating then repeating)
3) When should I add CYA to raise it? I've added several times this summer and am surprised it is as low as 35 but I triple- checked it today

I'm hoping that I have successfully removed the mustard algae but time will tell. No more extended trips away from home/pool should help.
thanks for your continued assistance!

[BigDave]

1) is there a way/procedure to use fewer drops of R-0871 when repeatedly testing FC at mustard algae shock levels? You can use a 5ml sample and multiply drop count by 1ppm. If you have a way to measure 5ml.



2) should I continue to lower TA (by adding acid to lower pH then aerating then repeating)I see no reason to move your TA.



3) When should I add CYA to raise it? I've added several times this summer and am surprised it is as low as 35 but I triple- checked it today Whenever you want to. How do you get 35ppm? Halfway between 30ppm and 40ppm?

[PoolDoc]

1) is there a way/procedure to use fewer drops of R-0871 when repeatedly testing FC at mustard algae shock levels?
If you are using the 10 ml sample, then there's no further improvment. However, you can (with practice) learn to eyeball an OTO tester, so you can use it instead. To do so, you'll need to practice by testing with BOTH the FAS-DPD and an OTO kit at the same time.


2) should I continue to lower TA (by adding acid to lower pH then aerating then repeating)
It's low enough . . . unless you want to do borates, which will make your pool significantly more resistant to algae. Info here:
http://www.poolforum.com/pf2/showthread.php?18597


3) When should I add CYA to raise it? I've added several times this summer and am surprised it is as low as 35 but I triple- checked it today
35 is pretty low -- if you can get a box of PoolBrand dichlor bags at Sams Club, I'd do that. If not, I've posted links below for Amazon. It's very hard to buy un-gooped-up dichlor otherwise. But the big question is, does your pool leak? That, or excessive backwashing, would be the only reason for dropping CYA levels. (You know you should ONLY backwash when your filter pressure increases at least 5 psi over clean pressure, right? Your pressure gauge DOES work, right?)

I emailed you links to your Pool History Chart.

Ben
================================================== ==========

+ If you need stabilizer, and have access to a Sams Club, buy their 24 pack of 1# bags of dichlor shock (www.samsclub.com/sams/shop/product.jsp?productId=108822). Each bag will add about 7 ppm of chlorine, and about 6 ppm of stabilizer, per 10K gallons of water. Otherwise, order dichlor from Amazon:
Kem-Tek Dichlor 22 lbs (http://www.amazon.com/exec/obidos/ASIN/B0030BEHZA/poolbooks)We do NOT recommend buying dichlor locally, otherwise, at least until you are an EXPERT reader of chemical labels. The chlorinating pool chemicals sold at Walmart, Kmart, Costco, and most other local stores are diluted blends, sometimes with copper and other products with bad side-effects.

[PoolDoc]

Ahh-h.

Simul-responders . . .

BigDave, I don't think there's a 5 ml marked point on the tester, is there? I'll have to go look.

[Charlie_R]

There is a 5mL mark on the tube you get with the HTH 6 way, so is it ok to use that, and have a 1ppm resolution?

[PoolDoc]

Yeah, if you can see the color change (pink to clear) that would be fine.

[Kateyru]

My head is spinning...

okay, I use K-2006 kit and no 5ml marker so I might could TRY to guess at 5ml...or use a measuring cup or spoon. I also have a basic OTO test kit, just fyi. My Walmart doesn't have that HTH test kit.

will leave TA alone for now...would love to do the borate thing but want to make sure algae is really gone.

CYA at 35 was my eyeball estimate. If I add Sam's dichlor, I'm sending FC back up, correct? Do I need to?
I don't think pool leaks but we add water regularly/daily. I live in summer hell, oh, I mean Montgomery, Ala where it is very hot and very humid. I don't backwash often, pressure rarely moves much. Great thought about the gauge, how would I know if it works correctly?????
Ben, I just saw email with pool hx in inbox and will get on that.
Would one of you guys please move to Montgomery :)
Thanks, thanks!

[PoolDoc]

will leave TA alone for now...would love to do the borate thing but want to make sure algae is really gone.

Actually, borates would help with that.

But . . .


I don't think pool leaks but we add water regularly/daily.

Sounds like a leak. You need to do a bucket test, to find out:
http://www.poolforum.com/pf2/showthread.php?11252

[Kateyru]

ok, will do test. Should pump be on overnight for the test?
thx