Is The Bloom Dead?

Algae problems in swimming pool water.
Green (cloudy) water or slimy pool walls.
Black algae. Mustard algae. Pink or white pool mold.
Jack Sparrow
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Is The Bloom Dead?

Postby Jack Sparrow » Tue 07 Aug, 2007 08:35

Ok, I've been shocking the snot out of this pool now for 4 days waiting for it to turn that beautiful aqua color of cloudiness. I have kept the FC levels anywhere between 16-20ppm (CYA 40ppm) during this entire period. My last FC reading last night was 15.5ppm and this morning it was 14.5. I did wake up this morning to a perfectly aqua colored pool with no green suspended algae. But, what concerns me is the very small patches of algae that are sitting on the bottom (they sort of look like a bloom when it first occurs). Yes there are the bigger clumps that need to get vacuumed, but are the smaller ones scattered throughout to be concerned with or are they just more that needs to be vacuumed? Incidently, I did brush the pool probably 6 times throughout the shock period.


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Postby chem geek » Tue 07 Aug, 2007 09:04

It does seem that your pool took longer to kill the algae than most. Did the sequence look like that in this link ? A few hours after the initial dosing of shock levels of chlorine, the algae should have settled (if there was a lot of it). You'll notice that the pool continues to have a green tinge, though is mostly cloudy, until the vacuuming is done. Other examples are shown here and here .

If you have a pool without a floor drain, such as most above-ground pools, then the circulation is poor near the bottom and you may need to use a flocculant, OMNI Liquid Floc Plus, which will help consolidate all suspended particles and allow you to vacuum to waste more efficiently.

Since your chlorine has mostly held overnight, it does appear that you have killed the bulk of the algae and are now at the stage of clearing the suspended particles. The chlorine will continue to break this down, but that can take a while so the floc can help speed that up via physical consolidation and removal. Also, be sure and check your filter and clean it (backwash if sand; clean if cartridge; clean or backwash as appropriate for DE) as there may be dead algae there as well.

I suggest vacuuming first (both large and small clumps) and see where you are at. If the water presists at cloudiness, then use a floc (per instructions, turn off the pump and wait overnight after adding the floc) and vacuum again.

What sort of test kit did you use to determine the 40 ppm CYA? I'm just wondering if that was an accurate number. It seems like the pool might have a somewhat higher CYA which might be why it took longer to clear. Either that, or the pool may be high in phosphates which makes algae grow faster (though chlorine can still kill the algae).

Richard
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Postby Backglass » Tue 07 Aug, 2007 09:44

Yup, you are almost home. Now, filter, filter filter. I always vacuum what I can off the bottom, then brush the entire pool so the filter can get the rest. The next morning it will have settled...and do it again. A few days of this and you will get it done. Keep your chlorine high and your filter running 24/7 until your clear...the end is near!
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Postby Jack Sparrow » Tue 07 Aug, 2007 10:28

chem geek wrote:It does seem that your pool took longer to kill the algae than most. Did the sequence look like that in this link ?

This algae bloom never turned the water green, it was predominantly on the bottom and the sides-- Not until I brushd it did it turn the water. This was a fast grower! 8am I had small patches, 4pm I had a deep end covered in algae.

chem geek wrote:A few hours after the initial dosing of shock levels of chlorine, the algae should have settled (if there was a lot of it). You'll notice that the pool continues to have a green tinge, though is mostly cloudy, until the vacuuming is done.

Actually, it isn't green at all, just cloudy now.

chem geek wrote:If you have a pool without a floor drain, such as most above-ground pools, then the circulation is poor near the bottom and you may need to use a flocculant,

This is an in-ground 16x32 but has no floor drain, just the typical skimmer and second side intake with two returns set to create a counter-clockwise current.

chem geek wrote:OMNI Liquid Floc Plus, which will help consolidate all suspended particles and allow you to vacuum to waste more efficiently.

I'm gonna wait another 24 hrs on the floc as it seems hour by hour it's clearing. I have one dose left of Super Floc (from Leslies) that I'll use if necessary. One thing that sucks is this floc requires the FC to be below 3ppm. There's no way I'm bringing my FC that low ever again (it was my target for a long time, but with this warmer weather proved to not keep the algae under control-- and the 11.5% rule tells me I should be at 4.6 and I'll shoot for 5%)

chem geek wrote:Also, be sure and check your filter and clean it (backwash if sand; clean if cartridge; clean or backwash as appropriate for DE) as there may be dead algae there as well.

Throughout the shock process I backwashed every 12 hours and I added my bleach through the skimmer just to hit the sand a little harder.

chem geek wrote:I suggest vacuuming first (both large and small clumps) and see where you are at. If the water presists at cloudiness, then use a floc (per instructions, turn off the pump and wait overnight after adding the floc) and vacuum again.

Good idea. I'll head out there after this post.

chem geek wrote:What sort of test kit did you use to determine the 40 ppm CYA? I'm just wondering if that was an accurate number. It seems like the pool might have a somewhat higher CYA which might be why it took longer to clear.

K-2006. But... the number I went by was a week old. I could have been a bit higher as I have been using trichlor-- maybe as high as fifty, but no more. Incidentally, I'm done with the tabs as I don't want this CYA to get any higher. I'm waiting on my CYA regeant refill from Taylor so I can test again.

chem geek wrote:Either that, or the pool may be high in phosphates which makes algae grow faster (though chlorine can still kill the algae).

This is one question that has consumed me lately-- phosphates. I think that's the culprit. But, I can't understand how I achieved such high levels (if indeed I have high levels) as I don't have leaves, etc. in the pool (Polaris to the rescue). Can heavy swimmer loads add phosphates (sunscreens, tanning lotions, probably urine (I never see these kids get out and go to the bathroom!), etc.)?
Seems like all the neighborhood kids want to swim here (which I have no problem with, that's what a pool's for!). I'm gonna buy a phosphate killer just to be safe.

Thanks,
Joe
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Postby chem geek » Tue 07 Aug, 2007 10:54

Joe,

My responses are below yours.

Jack Sparrow wrote:This algae bloom never turned the water green, it was predominantly on the bottom and the sides-- Not until I brushd it did it turn the water. This was a fast grower! 8am I had small patches, 4pm I had a deep end covered in algae.

If the patches were mustard/yellow/brown in color and were more like dust, then that could be mustard/yellow algae which takes more chlorine to kill and keep away than green algae.

Jack Sparrow wrote:This is an in-ground 16x32 but has no floor drain, just the typical skimmer and second side intake with two returns set to create a counter-clockwise current.

So the circulation near the bottom will be poor so brushing regularly or using a pool sweep will help get that bottom water up and into the skimmer. Pointing at least one return down and to the side (i.e. diagonal) will have the spiral current swirl more at the bottom, hopefully stirring it up.

Jack Sparrow wrote:I'm gonna wait another 24 hrs on the floc as it seems hour by hour it's clearing. I have one dose left of Super Floc (from Leslies) that I'll use if necessary. One thing that sucks is this floc requires the FC to be below 3ppm. There's no way I'm bringing my FC that low ever again (it was my target for a long time, but with this warmer weather proved to not keep the algae under control-- and the 11.5% rule tells me I should be at 4.6 and I'll shoot for 5%)

Not all flocs require low chlorine levels. OMNI Liquid Floc Plus actually works better at higher pH (7.5 - 8.0) that is typically seen at shock levels of chlorine.

Jack Sparrow wrote:K-2006. But... the number I went by was a week old. I could have been a bit higher as I have been using trichlor-- maybe as high as fifty, but no more. Incidentally, I'm done with the tabs as I don't want this CYA to get any higher. I'm waiting on my CYA regeant refill from Taylor so I can test again.

It probably didn't go up very much. For every 1 ppm FC added by Trichlor, it also adds 0.6 ppm to CYA.

Jack Sparrow wrote:This is one question that has consumed me lately-- phosphates. I think that's the culprit. But, I can't understand how I achieved such high levels (if indeed I have high levels) as I don't have leaves, etc. in the pool (Polaris to the rescue). Can heavy swimmer loads add phosphates (sunscreens, tanning lotions, probably urine (I never see these kids get out and go to the bathroom!), etc.)?
Seems like all the neighborhood kids want to swim here (which I have no problem with, that's what a pool's for!). I'm gonna buy a phosphate killer just to be safe.

Phosphate removers are expensive and should not be necessary. Phosphates and nitrates are in fertilizer so can get blown in from soil and nearby fields that get fertilized. The phosphates don't come from swimmers (some nitrates can, however, but not in large quantities) unless the kids played in fertilized dirt and then went into the pool. I think the problem was just that the chlorine level was on the low side relative to CYA, especially for mustard/yellow algae. If it's really mustard/yellow algae and if that gets frequently reintroduced (say, from swimsuits the kids wear and don't wash in soapy water) then an FC level of 15% of the CYA level may be needed to keep it away. If you had 3 ppm FC at 40 ppm CYA, then that's right at the bare minimum of 7.5% to keep away green algae so setting a target of 5 ppm will probably be OK -- if not, then a minimum of 6 ppm FC will keep away even mustard/yellow algae.

If you find you can't or don't want to maintain the higher FC level, then instead of using a phosphate remover, I would suggest (after the FC level has lowered to normal levels) using an initial dose and then a weekly maintenance dose of PolyQuat 60 algaecide. Though the phosphate treatment will also work, it may also need reapplication if more phosphates are introduced and as I said, it's expensive (so is currently the rage among pool stores). Chlorine alone will kill algae, even in the presence of phosphates, but the PolyQuat algaecide will let you use lower FC levels that are focussed on killing bacteria and viruses while the algaecide inhibits algae growth. This also lets you not worry as much about the CYA level. It's a cost/convenience tradeoff and is entirely up to you.

Richard
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Postby Jack Sparrow » Tue 07 Aug, 2007 11:53

It's interesting, the algae is on the greener side (maybe a bit yellow) but for all other intents and purposes it has the characteristics of mustard algae.

Yeah, I think I'm gonna buy a couple of eyeballs for my returns to get them working the bottom more. I'll keep running the Polaris as well.

I might be wise to not use the floc from Leslies and get my hands on the Omni. Like I said earlier, there's no way this chlorine is coming down to 3ppm!

Ok, this phosphate thing is interesting. It sounds almost like a CYA thing. Chlorine won't burn it off and it doesn't go away on it's own. So, I assume diluting the pool water with draining and refilling is the only way (other than phospahte removers)?

We do have a creek near the pool and I'm always kicking out wildlife ie ducks, frogs, snapping turtles, etc. Possibly they're introducing the algea spores? I don't know. I'm just gonna have to keep the FC higher. The health factor is my biggest issue. Is 5-6ppm still considered safe for swimmers? Maybe no one really knows the long-term health risks of chlorine, especially at higher levels.

Joe
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Postby chem geek » Tue 07 Aug, 2007 20:44

Joe,

Your 40 ppm CYA level is fine. That isn't considered high and will help protect the chlorine from breakdown from sunlight (UV rays). Yes, the only way to reduce CYA is through dilution of the water, but as I say you don't need to do that.

As for having a 5 ppm FC level with 40 ppm CYA level, this is absolutely positively safe. The recommendations that talk about FC levels are independent of CYA and are really from the days of no CYA in the pool. The disinfecting chlorine level, which is hypochlorous acid, is very, very low in the presence of CYA. 5 ppm FC with 40 ppm CYA is equivalent to having 0.12 ppm FC with no CYA. This is far lower than is found in indoor pools that do not have CYA.

My wife's swimsuits degrade in just one winter season of swimming at an indoor community pool that has 2 ppm FC and no CYA, but in our own pool with 3-6 ppm FC and 25 ppm CYA over multiple summers there is no evidence of any degradation. Essentially, the oxidation capability and the disinfection capability of the chlorine in a pool with CYA is very, very low so is not harmful to your skin nor does it produce very many disinfection by-products (the reaction rates are about 20 times slower than in indoor pools where all reports of asthma and respiratory problems with competitive swimmers and small children are reported). The only issue would be if you drank the water and even then the 5 ppm FC chlorine amount is very low -- drinking water used to have 1-2 ppm FC or sometimes more (now, monochloramine is typically used at around 1 ppm, but the reason wasn't any toxicity with chlorine, but rather a small risk with chlorine byproducts, again with drinking).

Richard
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Postby Jack Sparrow » Mon 13 Aug, 2007 09:47

Ok, this is nuts.
I shocked (15-20ppm) and brushed the $%#@ out of this pool for 4 days. The pool turned chrystal clear on the 4th day with my levels not dropping more than .5ppm over night. I then have been keeping my FC at 6ppm with it slipping to 5ppm once.

So everything was good... for 4 days. Sure enough, the mustard algae was back. A couple of small patches were seen on the bottom on Saturday. I immediately jumped on it and shocked (20-22ppm) for 36 hours. Because I caught it early, it was irradicated quickly, or was it?-- at this point I don't know anymore. Ya know, a horror flick could be made about pool algae: "Revenge of the Algae" with a sequel named "Revenge of the Algae: the Re-Bloom".

Anyway, the only thing I can think of is I didn't disinfect everything, especially the Polaris. I wasn't aware of the need to disinfect in reading on this forum until it was suggested to me in a post.

If I may make a suggestion to everyone, in offering instruction in the future on this topic, be sure to include the disinfecting part.

My final deduction... chlorine alone is not going to keep this away, unless we swim at 15ppm!, algaecide will be part of my weekly maintenance from now on.
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Postby chem geek » Mon 13 Aug, 2007 11:14

You are right that disinfection of all pool parts is required to avoid reintroduction. Some people find that the algae lurks behind the pool light(s) as well. The 15% of the CYA level (6 ppm for 40 ppm CYA in your case) was the minimum needed to keep away mustard/yellow algae based on several other pool users so it does appear that's a "hard" limit since just dipping to 5 once was apparently enough to bring it back (or perhaps even more than 15% is needed).

As you surmised, you can use PolyQuat 60 algaecide weekly to keep this away. Please report back how this works since there isn't a lot of good data on whether this algaecide is as effective for this algae. Buckman Labs says it should work and we know that the algaecide alone will keep away green algae even with no chlorine (at least for a while), but we don't know about mustard/yellow algae.

Leslie's algae control, which is PolyQuat 60, is on sale for $55 for 1 gallon so at 4 fluid ounces per 10,000 gallons per week for maintenance, that's $1.72 per week. The PhosFree product is $37 for 3 liters (some more powerful removers sell for around $30 for a quart or $80 for a gallon). Though concentrations vary, most phosphate removers remove about 250 ppb phosphates by using somewhat less than 1 quart in 10,000 gallons. Maintenance dosage recommendations vary, but some say 1 quart per 10,000 gallons per week which is obviously very expensive and probably unnecessary unless a lot of phosphates get blown in regularly (usually from fertilized soil). So using a phosphate remover is another option, but it's harder to figure on its true cost.

[EDIT]
I found that SeaKlear (see this link may be found for $29 per quart and claims that 1 quart removes 1000 ppb in 20,000 gallons so is more effective than the Leslie's product described above (perhaps it's more concentrated). SeaKlear recommends using 1 fluid ounce per week per 5,000 gallons so that's 2 fluid ounces per week per 10,000 gallons (which will remove an additional 125 ppb) or around $1.81 per week per 10,000 gallons.

So the maintenance costs for PolyQuat 60 algaecide and for phosphate remover seem comparable. I'm not clear if the phosphate maintenance is as critically required unless phosphates are constantly being reintroduced into a pool.
[END-EDIT]

It would be interesting to know the phosphate level in your pool. Have a pool store check it and let us know what it is (you can do that when you buy the algaecide). You can also buy AquaChek Residential Phosphate testing strips which cost around 90 cents per test (strip).

Richard
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Postby Jack Sparrow » Mon 13 Aug, 2007 12:16

Hey Richard,
I went yesterday to Leslies and bought their "Algae Control" (took advantage of the gallon sale) which is basically Poly 60. I was indeed going to get the phophate level checked and spaced it. I'll have to do it another time as it's a 25 minute drive for me.

But, getting back to the FC levels... if I can't even allow the FC to drop even 1 ppm (from 6 to 5) without running the risk of the mustard returning, that's crazy. I'm not willing to sit by the pool 24/7 making sure my chlorine stays in line and I don't want to get my FC up around 7-8 for a cushion, that's too high for swimming in my opinion. I noticed my skin drying out much more even at 6-7ppm and my kids are always opening their eyes under water.

As far as cost, I might see pools a little differently than others, but I believe that if you're a pool owner you accept the fact that it's going to cost you some money to keep maintained. The money I would spend on extra-curricular activities (as opposed to swimming) for my kids through the summer would be much more than what I spend in maintenance. Plus my kids have become excellent swimmers and you can't put a price on that. Don't get me wrong, I still watch my expenditures, but I won't choose one method over another because it saves me 22 cents a week. I just want the best method of taking care of a pool and minimizing major issues that take the pool down for 3-7 days at a time.

What I have learned this summer through this forum and my own flounderings will save me so much in summers to come. Just getting away from tri tablets AND pound after expensive pound of calcium hypochlorite shock has put a smile on my face. Over time I'll perfect all this.....
and then I'll move! lol

Joe

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