Is The Bloom Dead?

[Jack Sparrow]

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.

[chem geek]

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

[Backglass]

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!

[Jack Sparrow]

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.

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.

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.

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%)

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.

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.

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.

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

[chem geek]

Joe,

My responses are below yours.

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.

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.

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.

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.

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

[Jack Sparrow]

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

[chem geek]

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

[Jack Sparrow]

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.

[chem geek]

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

[Jack Sparrow]

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

[chem geek]

Joe,

Understood. Though green algae is relatively easy to keep away with chlorine alone, yellow/mustard algae is much harder. Some pool users have done it with shocking to 60% of the CYA level (lowering the pH of the pool water to 7.2 before adding the chlorine to that level) and keeping it there for 2-3 days after there are no signs of algae, soaking pool poles, etc. Though this has worked for them, it's a royal pain and for some others the maintenance of 15% of the CYA level is also annoying. As you pointed out, it is a higher disinfecting chlorine level and is therefore more drying to skin, hair, etc. (though nowhere near as bad as indoor pools -- my wife can attest to that during the winter). It's also interesting that mustard/yellow algae seems to peak in August.

If you go the PolyQuat 60 algaecide or the Phosphate remover route, then you should be able to live with a rather low chlorine level. Keep us posted long term as it would be useful to know what that level is. Killing bacteria in the pool requires very, very low chlorine levels so it's really all about algae prevention. I'm guessing that an outdoor pool with the algaecide or phosphate remover probably needs around 2 ppm FC minimum just to have enough quantity in reserve to oxidize organics but that in practice with sunlight always breaking it down, you need to start with 3-4 ppm each day to end up with at least 2 and not run out even under bather load (but this depends on the size of the pool, number of bathers, etc.).

With the algaecide or phosphate remover, you could even raise your CYA level without causing harm and run at 3 ppm FC with 60-80 ppm CYA similar to most SWG pools. In theory, that should retain the chlorine longer so end up with less chlorine usage. Just make sure you catch and stop any algae that develops early as you've seen how even "dull" water or small amounts of visible algae can grow quickly if not inhibited or starved. Of course, it's not easy to reduce CYA once you've raised it.

We're all learning at this -- as far as what works best for each pool. Knowing the chemistry isn't the same as deciding what's best economically and practically. This thread on another pool forum is where I first picked up on mustard/yellow algae and with matt4x4 first figured out what it took to kill it and keep it away. Since then, other users have had similar experiences. Fortunately, not every pool gets this algae (unlike green algae which most pools will get if chlorine gets too low and an algaecide or phosphate remover isn't used).

Oh, one last thing. Though it sounds like your algae was truly algae, often yellow-green dust is actually pollen. So it will seem to frequently come back when it has nothing to do with chlorine levels or anything else. A definitive way to know is to take a sample and look under a microscope -- pollen is spherical, often with spikes, while algae looks like cells that are semi-transparent, sometimes in filaments. Usually, though, pollen is seen on the water surface and gets caught in skimmer socks. This is just FYI as your case sounded like algae.

Richard

[Jack Sparrow]

Richard,
I read through the entire thread you had linked to in your last post-- mine is definitely mustard algae. It's interesting though, some of those guys said it was only settling on the bottom while mine was clinging to the sides as well. But, like the description, it always starts on the shady side of the pool (the side that's shaded from afternoon sun) in patches and then progresses out from there leaving a film over the entire bottom with heavier, darker clumps in places. It's very easy to brush needing very little force bring it off the surface.
Here's the description for other readers:
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YELLOW ALGAE: A wall clinging variety, also called mustard algae, is usually found on the shady side of the pool. It is sheet forming, and can be difficult to eradicate completely. Once begun, a pool owner could spend the entire season fighting yellow algae; reinfection is common. This variety is resistant to normal chlorine levels and must be dealt with firmly. Hit it hard!

Yellow Algae Phaeophyta: (Also called Mustard Algae), It creates a slimy layer that guards it from sanitizers. When brushed, yellow algae is removed easily but returns quickly. Yellow Algae can set in on any pool or spa. Chlorine may slow its growth, but will not completely kill this strain of Algae. An algaecide must be used to effectively kill and prevent this Algae.
-------------------------------------------------------------------------------------

I'm concerned that my 16-20ppm didn't kick it since these guys in the other forum were upwards to 25-30ppm to kill this stuff. My water is chrystal clear with no CC and no overnight consumption now, but with this algae the big question is: is it really dead? and is it only time until a reinfection?

Sounds like the PolyQuat 60 is the way to go to fend this stuff off. I'll keep you posted.

Joe

[Jack Sparrow]

OK, it's been a week since my last post on this issue and I'm reporting back.

On Aug. 14, after a 36 hour shock at 20-22ppm, I added Leslies "Algae Control" which is their version of PolyQuat 60. I used their initial dose recommendations for a pool that had visable algae (although mine did not) just to be safe. I have since followed the recommendations for weekly dosage (they recommend every 5-7 days and I'm using the shorter 5 day period).

Anyway-- beautiful water free of any kind of algae. My numbers remain incredibly stable and I'm able to keep much lower FC levels-- 3ppm. I even, accidentally, dropped to 1.2ppm (my dog died that day) and still no problems:
FC- 3
pH- 7.5
Alk- 120
Hardness- 240
CYA- 35

So, I think I can safely say (at least to this point) that the introduction of PolyQuat 60 will really help in the ongoing algae battle. Yeah, it's not cheap, but I'd much rather spend the money and have more swim days, less work, and less headache.

Signing off for now until my next catasrophe!

Joe

[chem geek]

Joe, thanks for the report back. It's good to know that it seems that PolyQuat will be effective against yellow/mustard algae. We knew it was good against green algae but had no real user experiences with using PolyQuat 60 to prevent yellow/mustard algae. Thanks for (unwittingly) being the guinea pig on this one.

It's true that it's not cheap, but $2 per 10,000 gallons per week is insurance and apparently effective.

Richard

[gonefishin2]

OK, it's been a week since my last post on this issue and I'm reporting back.

On Aug. 14, after a 36 hour shock at 20-22ppm, I added Leslies "Algae Control" which is their version of PolyQuat 60. I used their initial dose recommendations for a pool that had visable algae (although mine did not) just to be safe. I have since followed the recommendations for weekly dosage (they recommend every 5-7 days and I'm using the shorter 5 day period).

Anyway-- beautiful water free of any kind of algae. My numbers remain incredibly stable and I'm able to keep much lower FC levels-- 3ppm. I even, accidentally, dropped to 1.2ppm (my dog died that day) and still no problems:
FC- 3
pH- 7.5
Alk- 120
Hardness- 240
CYA- 35

So, I think I can safely say (at least to this point) that the introduction of PolyQuat 60 will really help in the ongoing algae battle. Yeah, it's not cheap, but I'd much rather spend the money and have more swim days, less work, and less headache.

Signing off for now until my next catasrophe!

Joe

Hi Jack! I sure hope your battle is over...it sounds like it's been a vigorous fight.

I am looking for samples of mustard algae for comparison under a microscope with other samples. If your algae does come back...would you be interested in collecting a sample for me? I'd greatly appreciate any help you can give.

I tried to register here but it didn't work (hmmm...stop smiling chemgeek ) If your interested could you send me a private message over at troublefreepools?

thanks a bunch!

dan