First Shock with BBB Method for mustard Algae

[geri]

We've been preoccupied with a pet emergency for the last couple weeks and the pool has been a little neglected. (One of our parrots broke his leg.) The pool went ten days without removal of the bubble cover and testing. Normally, I am pretty religious about maintaining the pool and keep the FC at or above the BBB recommended level relative to CYA (currently 4-6 PPM). Historically the chemistry in our pool remains exceptionally stable. Normally I test once or twice a week and this pool historically has a very low chlorine demand. [When we bought this house and I began maintaining the pool the CYA was over 120 and it has taken a rainy winter and a few short drain and fills to over more than a year to get it down to about 50. Next winter I will have it where I want it (Water here is very expensive.)]

Yesterday afternoon I tested and found the FC to be 1.0 ppm and PH @ 7.5. All I had time to do was add chlorine and test. Yesterday evening I did a basic test again and FC was at 6.2 and PH 8.0.

This morning I did a full battery of tests and removed the cover. The numbers are as follows:

FC 6.2
CC 0
PH 8.0
TA 100
CH 375
CYA 50
Temp 82 f.

So there was no chlorine loss overnight; there is no CC and the water looks clean and clear. Problem is that there is a big patch of Mustard / Yellow ? Algae on the North facing side and some small areas on the north facing risers of the the top two shallow end steps. From what I've read you guys say shocking is mandatory if there are signs of algae.

It seems kind of a shame to dump all that Chlorine in there, but I have come to trust you guys implicitly.

Anticipating a big bump in PH with the added ChIorine in the last hour I adjusted the PH down to 7.2 and my plan is to raise the FC to 20.

So, what is the minimum time I have to hold the pool at shock level?

I have done a good brush down and will repeat.
How aggressive should I be in cleaning? light housing? skimmer parts, drain?

Should I add something to my sand filter like "Fiber Clear" to increase its effectiveness?

I expect it will take quite some time for the FC to come down from shock level, because as I remarked above the FC seems to be holding at its current level and this pool has a historically low chlorine demand. I know this question gets answered frequently but is it really okay to swim at this high chlorine level?

I know you guys aren't crazy about polyquat but I am contemplating on using some as more of a "belt and suspenders approach. Are there any drawbacks to using this chemical other than cost? (Yes, I know "it's no substitute for proper chlorine sanitization.

THANKS IN ADVANCE FOR YOUR ANSWERS AND COMMENTS.

 

[Barbara C]

Hi! First off I want to let you know I've never had mustard algae but from what I've gathered from the pool school, I will give a few suggestions!
I am a bit confused that you can hold chlorine overnight.
Anyway....
As far as your question about polyquat based algaecides, they" can be used as a preventive measure, but are ineffective at fighting algae once you have it." That's straight from the pool school. I have no experience with them!

You said you plan to shock at 20. Chem Geek suggests in a CYA/Chlorine chart that your shock level should be at 29 for mustard algae.
CYA ........... Min FC³ ..... Target FC ...... Yel/Mstrd Min ...... Shock FC ..... Yel/MstrdShock
0 ................. 0.07¹ ........... 0.11¹ ................ 0.15¹ .................. 0.64¹ .............. 1.50¹
10 ............... 0.8¹ ............. 1.2¹ .................. 1.6¹ .................... 4.5 .................. 7.1
20 ............... 1.5¹ ............. 2.4 .................... 3.1 ..................... 8.3 ................ 12.7
30 ............... 2.2 ............... 3.5 .................... 4.6 ................... 12.2 ................ 18.2
40 ............... 2.9 ............... 4.6 .................... 6.1 ................... 16.0 ................ 23.8
50 ............... 3.7 ............... 5.7 .................... 7.5 ................... 19.8 ................ 29.4²
60 ............... 4.4 ............... 6.8 .................... 9.0 ................... 23.7 ................ 34.9²
70 ............... 5.1 ............... 8.0 .................. 10.5 ................... 27.5² ............... 40.5²
80 ............... 5.8 ............... 9.1 .................. 12.0 ................... 31.4² ............... 46.1²
90 ............... 6.6 ............. 10.2 .................. 13.5 ................... 35.2² ............... 51.7²
100 ............. 7.3 ............. 11.4 .................. 14.9 ................... 39.1² ............... 57.3²
120 ............. 8.7 ............. 13.6 .................. 17.9 ................... 46.7² ............... 68.4²[/size]
Sorry about bringing the whole chart here. I'm not very good at the computer thing!

You sound on target with brushing.
Normally, you would shock until you meet the three criteria for shocking, 1 clear water, 2 pass overnight chlorine test, 3 CC at 0.5 or less. What I'm saying is, I don't know since you seem to meet the criteria already.

I wouldn't swim at FC20. I think it's suggested that it's okay to swim at below regular shock levels but above that, I don't know. I suppose that's not much help.

Hope you can get things straightened out and hope your parrot is doing better. Hopefully someone with more knowledge will be along soon to help more!

 

[geri]

Thanks Barbara,

The 20ppm number came from the "pool school" chart. I guess it is just the "basic" chart. Who knew there were special values for Mustard/ Yellow Algae.

So now the question is should I raise the chlorine level to 29? Four hours ago I brought the level to 22ppm (overshot the original # just a bit.). I just tested again and it remains at 22. The pool is now about 2/3 shaded. I plan to check again at sunset and of course in the morning for an "overnight".

I gave it another thorough brush and everything still looks great.

My dilemma is that I will have guests who are going to want to swim on Saturday. I have seen many posts here that indicate you can swim up to shock level relative to CYA, but the 29 level sounds clearly too high for swimming. What to do? If we can swim and I can easily keep the level at 20 for the next couple days I'm thinking I will wait. If further advice is clear and 29 is the number then I will bump it up Saturday night and go from there.

 

[Barbara C]

Wish I could give you some definitive answers. You're right about the "up to shock level" being safe for swimming. I knew there was a good way to put it but just couldn't come up with it! You can always try keeping your FC at 20 until after Saturday and then really go hard at it. Does the algae come off the wall when you brush and then show back up again?? Like I said, I have no first hand experience with MA.

It seems we're a little low on moderators today, but I'm sure someone with some real knowledge will be along.

 

[257WbyMag]

It seems we're a little low on moderators today, but I'm sure someone with some real knowledge will be along.

:-D

Actually Barbara, you are doing just fine!

Geri, most people who think they have mustard algae generally do not. It is usually dust or plain ol' regular algae. As Barbara mentioned, if you brush it away and it returns to the same spot, it probably is algae and you need to treat it as such by shocking and brushing and all that stuff. The key is bringing the FC of your pool to shock level and holding it there until you algae symptoms are gone. For MA, 29 is your shock FC.

Swimming when shocking is not recommended. Not only because it isn't good for you, but also because it hampers your efforts to clear your pool. Adding a bunch of human bodies into a pool that you are trying to eliminate biological debris from makes it that much tougher. And in the case of mustard algae, you really don't want anyone or anything in there until the algae is gone. This is because mustard algae likes to hide out on pool toys and bathing suits, only to reintroduce itself into a clean pool environment once again after the problem has been fixed.

Pleas read Defeating Algae for further information.

 

[Barbara C]

"Swimming when shocking is not recommended. Not only because it isn't good for you, but also because it hampers your efforts to clear your pool."

I learned something new today! It never occurred to me that bodies in the pool will slow things down! I also didn't know about mustard algae being sneaky and hiding on bathing suits and all. I think I'll go add some bleach to my pool now just to make sure we don't get it!

 

[geri]

Geri, most people who think they have mustard algae generally do not. It is usually dust or plain ol' regular algae. As Barbara mentioned, if you brush it away and it returns to the same spot, it probably is algae and you need to treat it as such by shocking and brushing and all that stuff. The key is bringing the FC of your pool to shock level and holding it there until you algae symptoms are gone. For MA, 29 is your shock FC.

Swimming when shocking is not recommended. Not only because it isn't good for you, but also because it hampers your efforts to clear your pool. Adding a bunch of human bodies into a pool that you are trying to eliminate biological debris from makes it that much tougher. And in the case of mustard algae, you really don't want anyone or anything in there until the algae is gone. This is because mustard algae likes to hide out on pool toys and bathing suits, only to reintroduce itself into a clean pool environment once again after the problem has been fixed.

Pleas read Defeating Algae for further information.

Yes, Thank you, I have read defeating Algae.

What do you mean by "Dust?" Like the algae in an aquarium? Haven't had an aquarium in a long time but isn't that really green? "Regular algae"? What's that look like? After brushing how long before I would expect to see it return? If brushing is what I am supposed to do to get rid of it why wait to see if it comes back. Either way it sounds like shocking is the thing to do, and you appear to be saying that any algae should be treated as Mustard Algae.

I understand that swimming while shocking is not helpful to the process but what is unclear in my case is when do I consider the shocking finished? The water in my pool looks clean and clear. The only symptom was the yellow patches I described that I easily brushed off. There is no measurable CC and the FC has held all day today at 22PPM. If anything the latest test (about half an hour ago) indicates a value slightly higher (there has to be a higher error rate with the smaller water sample and so many drops of reagent.) It is very difficult to see but there may the tiniest bit of cloudiness stirred up at the bottom in a few areas when brushing. Dead Algae?

I have decided not to raise the chlorine any more tonight. If I test in the morning and the FC is holding it sounds like you think I should still raise it to 29. So the question is how long should I hold it there given everything else looks fine.

Oh one other thing. What about my bubble cover? I figure I will leave it off tonight, but couldn't I sanitize it by leaving it in contact with the highly chlorinated water? Otherwise, what should I do with it? Won't it just reintroduce algae back into the pool?

Finally, given what I am looking at I am still unclear on when the shocking is over and the swimming can resume. There are posts all over this board saying that it is safe to swim at shock levels. I didn't think this meant that you should swim while shocking, but it seems pretty clear that I needn't wait until FC has dropped to the "target level" on the chart, or do you disagree?

 

[257WbyMag]

What makes MA different is its tenacity to remain present in your pool and its resistance to high levels of chlorine. This is why we recommend being more aggressive with it than with green algae (higher FC to shock). It also looks like dust or dirt that has settled in areas. If it feels slimy or not gritty, it's algae. If it brushes away, only to reappear in the same spot again really quickly, it's algae. If it is present on the vertical surfaces of the pool, then I would suspect algae and treat accordingly. You did mention that they easily brush off but what you didn't mention was if the spots you brushed returned or not.

You know that you are done shocking when...
1.) Your CC is 0.5 or less
2.) Your FC holds to within 1 ppm of loss or less overnight
3.) There is no more algae and your water is clear

Pool covers should be left off during shocking.

Swimming while shocking....we get asked this at least a couple of times a day. Have people gone swimming while shocking? Yes. Did they live to tell about it later? Yes. Is it a good idea? We think that it isn't and we will just leave it at that. Whatever you choose to do is up to you.

 

[geri]

If it brushes away, only to reappear in the same spot again really quickly, it's algae. If it is present on the vertical surfaces of the pool, then I would suspect algae and treat accordingly. You did mention that they easily brush off but what you didn't mention was if the spots you brushed returned or not.

I am convinced that it was algae, so this may be academic, but what does "reappear..... really quickly" mean. Minutes? Hours? Overnight? I brushed the pool twice yesterday and once again this morning. There have been no signs of reappearance.

The only bad news is that the FC did not hold overnight. It dropped from 22 to 18.5. So I have gone to 29 and plan on holding it into the evening for another overnight test. Pool still looks great and there is no measurable CC.

Again this may be academic but you didn't comment on my suggestion that your earlier argument appears to suggest that for the purpose of determining a shock value any algae should be treated is if it were Yellow / Mustard Algae.

Finally, the concerns about reintroducing algae to a clean pool have me thinking about the bubble cover. Should I clean and disinfect it somehow? Any suggestions on how to do this? What about other stuff.

 

[257WbyMag]

I am convinced that it was algae, so this may be academic, but what does "reappear..... really quickly" mean. Minutes? Hours? Overnight? I brushed the pool twice yesterday and once again this morning. There have been no signs of reappearance.

Hours.

The only bad news is that the FC did not hold overnight. It dropped from 22 to 18.5. So I have gone to 29 and plan on holding it into the evening for another overnight test. Pool still looks great and there is no measurable CC.

Sounds like a good idea. You want 1 ppm or less FC loss overnight.

Again this may be academic but you didn't comment on my suggestion that your earlier argument appears to suggest that for the purpose of determining a shock value any algae should be treated is if it were Yellow / Mustard Algae.

If you wish, for all intents and purposes, you can treat any algae as mustard algae and not be wrong in your approach.

Finally, the concerns about reintroducing algae to a clean pool have me thinking about the bubble cover. Should I clean and disinfect it somehow? Any suggestions on how to do this? What about other stuff.

I don't have any suggestions for cleaning your cover. Perhaps someone else might. Pool toys can be cleaned with a dilute bleach solution and all towels and suits should be laundered well.

 

[Barbara C]

Geri,
Sounds like you've been given great advice. About the cover, over in the baquacil conversion section, it's recommended that everything be cleaned with a 10:1 bleach solution. That at least gives you a starting point. Spread the cover out somewhere that doesn't have grass or at least grass that you don't care about if it dies. Douse the cover on one side with your solution and scrub it around, somewhat gently. You don't want to break the bubbles. They can then become algae traps. Rinse and repeat on the other side. I

If you're still at shock levels you also can just put the cover on and leave it for an hour or so towards the end of the process. I would make sure water gets on the top side too or maybe turn it over and repeat that way.

Hope that helps!

 

[geri]

Thanks Barbara for the advice on cleaning the cover. All the toys and floaties will get the same treatment.

Chlorine dipped last night only 2 ppm from 30 to 28 and I have been successful all day keeping it at 29 plus or minus 1 ppm. I am going to test once more before bed tonight and we will see what it looks like in the morning. In the mean time I have done two two very thorough scrub downs today and there is no hint of the algae returning.

I am hopeful that tomorrow will bring a good test result.

 

[geri]

Success!

Just as I was starting to get discouraged.

It took yet another day at shock level but this morning the FC loss was only 1 PPM overnight. The most frustrating thing about this experience was that I started with a clear and apparently clean pool. It seems very odd to be dumping all that chlorine into good looking water.

It took almost 10 gallons of 12.5% chlorine and nearly 2 ounces of 0871 reagent over 4 days to maintain the level at about 29ppm. Cost was about $50 including sales tax.

So shocking is concluded. Now there is the waiting for the Chlorine to come down to a point I can adjust the PH. Luckily I've lost some water to evaporation over the last couple weeks so topping off should get me started.

Hopefully I won't have to do this again for some time.

 

[kal2002]

Congratulations. Sounds like I am about ready to go through what you went through. I am not looking forward to it. If it takes 10 gallons of 12.5% chlorine, I will probably have to buy that much or more chlorine before I attempt to shock my pool since mine is a little bigger. I don't have a way to get 12.5% chlorine. I was going to get the 10% Kem Tek chlorine from Home Depot. Thanks for the heads up.

 

[Melt In The Sun]

kal, check the prices on that Kem-tek; near me it is quite a bit more expensive than using regular bleach from the grocery store.

 

[257WbyMag]

Good job Geri!

 

[kal2002]

Thanks for the reminder in pricing. In this area, a 2-gal box of Kem Tek 10% chlorine costs $6.76 or someting like that. Walmart sells their 182 oz 6% for $2.54. Because I will be buying a small quantity, it is easier to me to deal with less gals even if it costs a bit more. For regular use, I will go with Walmart's bleach. It is cheaper, I think. Additionally, the Walmarts around here do not always have their shelves stocked so I can't rely on them when I am trying to shock the pool.

 

[Barbara C]

I'm so happy to hear you're done. Way to hang in there! Just think what you may have spent if you had been advised by a pool store. I shudder to think about it!

 

[geri]

I'm so happy to hear you're done. Way to hang in there! Just think what you may have spent if you had been advised by a pool store. I shudder to think about it!

Barbara, a special thank you to you because you were there for me at the beginning! [BTW our parrot is doing much better. Last Friday the vet gave him a smaller cast and he's getting the use of his toes back.]

Not exactly all done. I still have to clean the bubble cover. Luckily my driveway is large enough. Now I just have to find some old clothes that I don't mind ruining with splashed beach/water.

Your comment about the pool store is interesting. Their reaction to my purchase of 12 gallons of Chlorine was that THEY could have saved me money. They recommended $12.00 worth of bromide and an extra gallon or two of Chlorine. I did a lot of reading during this process and I think that if my CYA was still at 120+ I would have done the bromide. Otherwise, I think it's pretty clearly inappropriate.

By the way the a fore mentioned pool store sells gallons of HASA Sani-chlor @ 12.5% for $3.00, and they have recently had $5.00 off coupons on 4 gallon case lots. That's way cheaper than store bleach or the Home-cheapo. This is in super expensive Marin County. Of course the sales tax is 9.25%.

Is there a board policy on mentioning particular pool store businesses? The people at our local outfit are very pleasant and well meaning. Of course they are not BBB but some of the management have taken a look at TFP. Over the last year I've got some interesting responses from them. Perhaps I will make another post relating my experiences with them. They're not that typical of of other exchanges I have seen described here.

 

[kal2002]

By the way the a fore mentioned pool store sells gallons of HASA Sani-chlor @ 12.5% for $3.00, and they have recently had $5.00 off coupons on 4 gallon case lots. That's way cheaper than store bleach or the Home-cheapo. This is in super expensive Marin County. Of course the sales tax is 9.25%.

I wish I can get a deal in chlorine like geri's but there are no sales here for that. I went to HD to buy Kem Tek's 10% chlorine. They have a sign that says $6.16 each if buy 6 so I did. It is not as cheap as geri's store and it is almost as good as Walmart's in terms of pricing except less pitchers to carry around.