Help newbie with Mustard Algae

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G

Galun

0
Apr 14, 2011
45
I had put in an automated pump to pump bleach into the pool. Well, the "downside" to the convenience factor is that I totally forgot about refilling the tank. Weather had been cold so we hadn't been using the pool. We were thinking about using the pool this weekend. Pulled off the solar cover and I was greeted with a slimy film like yellowish substance that can be easily brushed off, only on the shady side of the pool. Sounds like the dreded mustard algae. And I only have myself to blame for letting my perfectly balanced water get out of control. Checked FC, it's zero.

It will be my first time fighting algae after I fired the pool guy / store, so I would like a little guidance.

Stats this evening:
pH = 7.8
FC = 0
CC = 0
TA = 60
CH = 180
CYA = 40

Pool size is 20k gallons. I was in a hurry so I called up leslies for their recommendation. They said take pH down to 7.5 and put in 4lbs of 73% cal hypo, which I did. After checking the forums tonight, I have a feeling that my 4lbs may have been lost.

So, tomorrow, if I have to start over and do it right, it sounds like I should
1) Take pH to 7.2
2) Should I take TA higher? To 80 - 100?
3) Take FC to 24 (based on my CYA of 40 and 20k pool)
4) Keep it at 24 until it drops less than 1 overnight.
5) In the mean time brush pool like crazy

Sounds about right?

Thanks!
 
Your plan sounds good. I would stop any use of cal-hypo and use bleach or liquid chlorine to do your shocking.

Don't worry about TA right now. Concentrate on keeping the FC at mustard levels if you are sure its mustard algae.

You are done shocking when you can pass all 3 of the three criteria:
1. pool looks clean
2. overnight loss of FC is less than 1ppm
3. CC's are 0.5 or less

Good luck and keep us updated with your progress.
 
It sounds like it might be mustard algae, but for sure you have something growing. What is your pool surface? Here are my comments:
Galun said:
So, tomorrow, if I have to start over and do it right, it sounds like I should
1) Take pH to 7.2
2) Should I take TA higher? To 80 - 100?I wouldn't worry about this right now.
3) Take FC to 24 (based on my CYA of 40 and 20k pool)No, normal shock level is above 15 ppm FC for 40 ppm CYA (from poolcalculator.com), see my notes below
4) Keep it at 24 until it drops less than 1 overnight.Same as above, keep it at 15 or above
5) In the mean time brush pool like crazy
When passing the finished shocking criteria (see my sig), then go to mustard shock level for 24 hours and follow the instructions in the link below.

Sounds about right?
Click to expand...
Make sure you read: http://www.troublefreepool.com/pool-school/mustard_algae You only want to be a mustard shock level for 24 hours. Before that you do the normal shocking process. Being at high FC levels too long can damage surfaces. I would not use cal hypo, just bleach/liquid chlorine.
 
Day 1

By my calculation, 4 lbs of 73% cal hypo yesterday should take my 20k gal pool up to around 18 FC. I didn't check last night because it would be inaccurate anyways since there wasn't enough time to throughly dissolve and mix. This morning the measurement was FC 14, CC <0.5 (very very faint pink on the first drop of the second drop test solution), and pool turned slighly cloudy. So the chlorine is doing its job. pH is back up to around 7.7, probably due to the Cal Hypo, so I added a bit more acid.

I scrubbed the pool this morning and bumped up the pool pump to full speed. Tonight I will bump it up to 16 and hopefully I will pass the overnight drop test.

If I do pass the overnight drop test, then the plan tomorrow is to bump FC to 24 to really kill off the mustard algae. Scrub everything hard, wash filter, throw everything in touch with "contaminated water" into the pool.

Sounds about right?

Thanks.
 
I dont see why you cant use some Cal-hypo now as your calcium isnt too high, just watch it long term. I would pre-dissolve some in a bucket, and test as soon as you've given time for distribution. I like bleach as much as anyone, but it is Chlorine you have at your disposal. Might as well use some and save a little bleach. You're on the right track, and don't sound like a novice so keep after it. Keep your pH down and your chlorine up, you'll make it through pretty soon. It may take a little while to beat it it, but you will.
 
Day 2

Passed OCLT! FC dropped maybe 0.5, CC 0, water looked clear.

I noticed white sediment in the deep end of the pool. Since that is where I dumped in the cal hypo I thought it might be undissolved cal hypo. (used 8lbs so far). Now on second thought, can this be dead algae?

Filter pressure only went up by like 2psi so I think I will backwash after the entire treatment. I will take FC up to 24 and hopefully it will all be done tomorrow.

Is it safe to swim in FC 24 CYA 40 water? I want to go in later today to give it a good scrub everywhere.

Thanks!
 
I noticed white sediment in the deep end of the pool. Since that is where I dumped in the cal hypo I thought it might be undissolved cal hypo. (used 8lbs so far). Now on second thought, can this be dead algae?
Click to expand...
If it's white it's not dead algae but it is likely undissolved Cal Hypo if you "dumped it" like you say without first pre-dissolving. I assume your pool is plaster so there is no harm but I would brush it around and get it dissolved and into the main drain if you have one.
 
Day 3

Shock level maintained overnight at FC 24 with no CC.

I did get into the pool yesterday (day 2) to give everything a good scrub, but I kept the kids out. (They got into a rubber boat and had me push it around the pool instead). Water got more clear over time.

Hopefully this is it.
 

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