CYA over 100 with yellow/mustard algae

[PoolDoc]

Interesting. That pretty much rules out borates as having much impact on mustard algae. It's also amazing that you're having recurrent algae with FC=20 and CYA only 30 ppm.

I have to say, that while I'm sorry for your problems, I'm glad for the opportunity to test this out. The fact that you have no phosphates in your tap water certainly makes things easier. You will need to practice extreme vigilance in what chemicals you use, and avoid using ANY products made by United Chemicals, as well as most stain/scale products. You probably want to avoid clarifiers, flocs and any other 'enhancement' products.

But even there it will be interesting to track your phosphates, to see what makes them rise, after you lower them.

Thanks so much!

[BigDave]

Big Dave's Mustard Algae Experiment contribution:
I took the cover off March 26 and topped up.
After adding water, the FC was 10.5, CC 0.0, CYA < 30, and pH 7.4; temp. 64 F. No sign of mustard algae.
Over the next three weeks, I chlorinated with a total of 5lbs of dichlor keeping the FC at 15-20.
The pool collected quite a bit of debris during this period that I vacuumed into the filter; Backwashed on June 15.
June 16, FC 8.0, CC 0.0, CYA 70, pH 7.4, TA 80, CH 11, borates 30; temp. 78 F. No sign of mustard algae.
June 17, FC 7.0, CC 0.0, pH 7.4; temp. 83 F. No sign of mustard algae. We took our first swim - Yay!
June 18, FC 5.0, CC 0.0, pH 7.4; temp. 88 F. No sign of mustard algae, Kids swim. Added Bleach.

I'm not sure If I'll be a good case - time will tell. I've disposed of our old solar blanket that I suspect was harborage for the algae.
With the K-1106, I measure > 1000 ppb phosphate in my pool and 500 ppb phosphate in my fill water.
I have 2 quarts of Kem-Tek phosphate remover on hand and plan to bring the phosphate to 100 ppb.
I also plan to buy a new solar cover in July - We'll see if that brings the yellow back.

[MikeM]

Hi all. OP here, with an update. As posted before, my phosphate was quite high, in the 800-1000+ range. I ordered 2 quarts of the Clorox phosphate remover as suggested, and added it slowly over a couple weeks. No problem with the filter or clouding. But zero impact on phosphate level also. Still very dark blue using the K-1106 kit. I waited 2 weeks after treatment to re-measure. Very disappointed in that product.

Needless to say, I still have the mustard algae. It comes back every 1-2 days after brushing. With the very hot temps here in North Texas, it's been a little worse than usual.

Anyway, I'm looking for new suggestions on a phosphate remover that actually works, so we can continue this experiment. My local pool store has several products, but I'll defer to the experts here.

Thanks,
Mike

P.S. I've been maintaining FC in the 6-10 range. Here are the latest numbers:

FC=9.4
CC=0
pH=7.7
TA=75
CYA=37
CH=230
Borates=50

[chem geek]

The Orenda PR10,000 is one effective product and reasonably priced for the amount of phosphate it removes. A pint is around $25 and will remove 5000 ppb per 10,000 gallons so should be more than enough for your pool.

[MikeM]

Thanks chem geek. If those numbers are right, I would only need about an ounce of that product for my situation. Sounds like it may be too concentrated for normal residential pool use.

[chem geek]

You need to remove 1000 ppb from 18,000 gallons and for their product one quart (32 fluid ounces) removes 10,000 ppb from 10,000 gallons so you need (32 fluid ounces) * (1000 ppb / 10,000 ppb) * (18,000 gallons / 10,000 gallons) = 5.76 fluid ounces, NOT one ounce. Their pint has 16 fluid ounces so has more than you need, but it's not extraordinary and I don't think you'll find a less expensive bottle of another product.

[MikeM]

OK, my mistake. I reversed the 18/10 in my quick calculation. A couple quick questions: does this product contain a clarifier? Or will I need to buy a separate product for that? Where can I actually buy it? The orendatech.com site does not appear to have any sales functionality. I checked Amazon but they only sell 5 and 15 gallon sizes (a wee bit more than I need). A few pool sites appear to offer the smaller sizes, but not at the price you mentioned. Thanks.

[Pappy]

If you enter "orenda pr 10000" (including the quotes) YourTown, TX into google, example - "orenda pr 10000" Plano, TX - you might find it right around the corner from you.

Good luck!

Pappy