Mustard Algae in salt system pool

[karla]

Hey Guys,
My husband and I travel for work most of the time. We were home two weeks ago to find our pool water (30,000) looking green. I took in a water sample and was given instructions for mustard algae. We added 12oz of Shock & Clear and then 4 lbs. of shock granules. The next AM I cleaned and backwashed the pool and added 4 additional lbs. of shock. I repeated the process again the next AM. The water was very clear by the 4th day. I then took a sample in and added salt and chemicals per their instruction. We left on the 5th day to go back out of town. I have a college age son who is in and out of our house and had him check salt level and let me know how the water looked each time he stopped by. Yesterday he was at the house and called to tell me the water looked green again. It has only been two weeks since I was home and thought I had the problem corrected. I am going to be gone another two weeks. My first question is will it make my situation worse if I don't do anything until I get back and can be there to monitor the process? My second questions is did I not get rid of it the first time and what should I do now? I appreciate any help you can give me.
Please Help!!!!!
Karla

[PoolDoc]

Karla,

I don't know if you have time to fix it before you leave again -- think in terms of at least 5 days.

The simplest thing for you to do might be this:
#1 - Buy a cheap OTO / phenol red test kit AND 30 gallons of plain 6% household bleach.
#2 - Get your stabilizer level tested OR, if you can find a testkit that tests stabilizer with a liquid (no 'goofy-strips'!), buy and use that.
#3 - Test your pool water, and report chlorine, stabilizer and pH results back here ASAP.
#4 - After testing, add 6 gallons of bleach this evening.
#5 - Retest tomorrow AM and brush the pool if possible. If the chlorine level (OTO) is not DARK yellow, add another 6 gallons.
#6 - Read the "Best Guess" page, so you'll have an understanding of how your CYA (stabilizer) level determines the CORRECT chlorine level.
#7 - When you write back, include info on what type of pool (vinyl or concrete), when you are leaving, and how often your son can check the pool (every day, every other day, etc.)

Good luck!

[karla]

Ben,
I am actually gone right now. My son called and told me that it was green again. He will be there for awhile tomorrow. Will I cause damage to the pool if I don't do anything to it until I get home in about two weeks? Should I turn off the pump or leave it running. It will be hard for my son to follow the above steps because he is in the military and works 24 hr. shifts. He is not there on a consistant basis. My husband is worried we are ruining the pump, etc. The pool is a 16 x 32 vinyl pool. I sincerely appreciate any help you can give me.
Thanks,
Karla

[PoolDoc]

Damage? Probably not. As long as even a trickle of water flows through your pump and filter, it will be fine. Centrifugal pumps are overloaded by high flow, not low flow. (No flow will boil the water and cause other problems, though.)

Huge mess? Yeah.

If your son can't be there consistently, you are pretty limited in options.

Given your schedule, once you get back you can start working on it. It would help if you have a K2006 testkit (Amazon link in sig) and, if you have a cartridge filter, a new filter cartridge both waiting on you.

Do NOT use more algaecides and stuff -- it will just make it harder.

If your son can dump 6 - 8 gallons of PLAIN 6% household bleach in, every time he comes over, that will lessen the problem when you return. But, tell him NOT to wear his expensive uniform when doing so -- bleach seems to jump out and touch you, anytime you wear anything nice.

Good luck.

[karla]

Thank you so much for you help. You don't know how much we appreciate it. Should we leave the pump running while he is putting the bleach in until we return?
Thanks,
Karla

[PoolDoc]

Yes, the pump needs to be on when he adds bleach, and for a couple of hours after.

[karla]

Will the bleach discolor the vinyl liner?
Thanks,
Karla

[aylad]

Not at the doseage that Ben has given you, as long as it doesn't splash on the sides during the addition. The algae in the water will consume the chlorine pretty quickly, so you're not going to have that much bleach in the pool for very long. And I don't know if you ever got a good stabilizer level or not, but if there's any CYA in the water, the amount of bleach Ben is having you add will probably not even do much to clear up the pool--rather, it will help the situation not get any worse until you get back.

Just make sure that he either pours it in through the skimmer (as long as there is no other chemical in the lines) or pours it slowly, without splashing, into the return stream. Either way will help disperse it through the pool quicker. As a caution, tell him to wear old clothes--I've been putting bleach in my pool for 9 years, and I STILL ruin at least one new shirt each season.

Janet

[karla]

Janet,
Thanks for your help. Will we notice anything after the bleach is put in the pool. My son isn't there but my neighbors are doing what they can.
Thanks,
Karla

[PoolDoc]

Bleach want "discolor" it, but it might 'de-color' it, ie. remove some of the print.

It's not really a function of 'bleach' per se, but rather of how high the chlorine + CYA is, AND whether you have a chlorine bleaching resistant print or not.

There's no way to know whether you do -- Plastimayd seems to have mostly resistant liners but NONE of the liner makers will tell you who printed the sheet, or who made the vinyl sheeting, and without that info, you can't tell.