Is The Bloom Dead?

[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.
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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