Mustard Algae? Or chemical stain?

[polyvue]

Hi Vtattebury,

Sorry for your troubles. I'd strongly suggest that you "suffer through" whatever you have to do to reduce CYA before you attempt to shock. I just noticed from your initial post that you have an AG pool... how about half the water, all at once? Be sure to test CYA so you'll know if you're done draining. 30-40 ppm is probably good but no higher.

Then, increase TA by adding baking soda up to 70-80 ppm. Set pH somewhere between 7 and 7.5. The sweet spot is just a little lower than what you reported: 7.2-7.4

Find the most economical price you can for liquid chorine or plain bleach. I'd been using grocery store bleach 8.25% but lately switched to Wall Mart "Pool Essentials Chlorinating Liquid" because it has a prominent date code (fresh is best) and contains 10% sodium hypochlorite.

You will need a lot! You can use Ben's Best Guess chart or an on-line calculator (poolcalculator dot com) to figure out how much to start with. I recommend using the suggested level for Shock Mustard Algae. There are instructions somewhere on this site and also at the place I love to hate: TFP (they use the term 'slamming' instead of 'shocking').

I think the pool calculator recommended FC 22 ppm for the amount of CYA I had in my pool so I dumped in enough chlorine to get it to 25-28 ppm and kept it above 22 ppm for several days. Brushed, doubled the run time on my filter pump, did every thing I could think of ... added bleach usually at night to reduce the amount sacrificed to the sun. After a few days the mustard/brown color had faded significantly. Then I allowed the chlorine to come down so I could swim.

Thanks for posting the links to the pictures.

For what it's worth, it looks exactly like the algae that affected my pool earlier this summer. The brushing was only marginally helpful with the algae in my pool but I would still recommend that you do it once a day while shocking. I've kept my FC level quite high (20-30% of CYA) since shocking for three days last month. I'm still not finished and there is residual algae baked into the strangest places! When it gets a bit cooler I will resume shocking and finish the job.

I visit this forum only every couple of days or so but if you need help I know there are others who can assist. Good luck to you.

[FormerBromineUser]

Yea, I don't like you using pucks with your CYA that high

Did you try using a vitamin C tablet on those stains? I might have missed it...

[Vtattebury]

Vitamin C? Never heard of that. The same pills we eat? Does it matter if chewable or not? I'm serious. Really never heard of that technique, but I guess you're just rubbing citric acid into it, huh?

[FormerBromineUser]

Yup. Actually ascorbic acid. Just the pills you get at the pharmacy. Get the tablets. And yes, half the water to dilute by half.

My liner cost many thousands but I have an inground 27K pool. Don't know about the cost for AG. You could probably get a quick quote for AG.

[Vtattebury]

Great, thanks for the info. I guess since I have about 90, of have to get rid of half my water to even get to 45, right?

Good to know that brushing didn't do much, because I've been brushing and there's literally no change.

Here's a random question-- anyone know how expensive a new pool liner installed is? Many thousands?