Recurring Mustard Algae And Fed Up!

by Anita
(Lakewood Ranch, FL)

We are renting a house with an 10,000 gallon in ground saltwater pool with a cartridge filter. For the third time in a little over a year we have mustard algae. The guy that was taking care of the pool said that all the chemicals are fine but occasionally the phosphates increase causing the algae.

It's getting very frustrating when we can't use the pool for a few days at a time while it's being treated let alone the increase in our power bill due to the continues run of the filter. He shocked the pool and also added a phosphate remover and in a 2-3 days the pool is swimmable but has a VERY strong chlorine smell.

It upsets me to add liquid chlorine to a salt water pool although I understand that the chlorinator turns the salt into chlorine already just minus the smell. Is there a way to control the phosphates before they get to the point of producing algae and having to spend $44 on a quart of phosphate remover plus not being able to use our pool?

We are now taking care of the pool ourselves due to an increase in rent if we didn't. Again we have an algae issue. I'm hoping that maybe Phosfree or some other product will help to keep the phosphates at a minimum. I can see several of our neighbors pools and none of them seem to be having any problems. The pool store tested the water on July 2nd

Chlorine 1.0
PH 78
Alkalinity 110
Phosphates 1000+
They said to do and 8hr boost and add 1pt of sulphuric acid

They tested the water again on July 7th

Chlorine 1.0
PH 78
Alkalinity 110
Phosphates 1000+

They said to do a 12hr boost and add 1qt sulphuric acid and needed phosphate remover which I couldn't do until I got back from out of town on the 11th. They tested again on July 11th

Chlorine 0
PH 78
Alkalinity 80
Phosphates 1000+

They said to brush pool down and add 1 jug of liquid chlorine and 1qt sulphuric acid. Today add 1qt Phosphate Remover
Clean filter daily
Take water sample in tomorrow July 13th

Today the water is very cloudy and has a blue tint. Loads of little winged bugs and a film on the water surface. This is getting very frustrating since we can't swim in it. We're due to have company this Friday and hoping the pool clears up by then. What are your thoughts on this problem and is the pool store telling us correctly?

I'd like to prevent this issue in the future if possible. Any help is greatly appreciated

Thanks for the great question Anita

And I hope you get this reply because it seems you didn't leave any email address. There's nothing on my end to say that you'll get an email from me saying your post has been answered. First, thanks for the readings because it makes the process go faster. I'd like you to read these recent posts:

High Phosphates Over 1000 & Cloudy Water

High Phosphate Levels And Low Chlorine Issue...

I hope many people read your question and my answer. Here it is: It doesn't matter the phosphate level in the pool. I don't care what the "guy at the pool store" says. Phosphates are food for algae. The chlorine kills the algae. If you keep the chlorine level between 2 - 4ppm and the cyanuric acid (CYA) between 30 - 50ppm, there's no algae because the chlorine kills it. Phosphates are safe to swim in. It doesn't matter the level of phosphates.

You're wasting your money on phosphate removers because it doesn't matter the phosphate level because the chlorine kills the algae, and so if there's no algae in the pool (and that's what you want) because you're keeping the chlorine level between 2 - 4ppm and your CYA between 30 - 50ppm, then there's no reason to worry about phosphates because the chlorine kills the algae.

No, that's not a typo. Yes I repeated myself, purposely. Anyone who has a phosphate "problem", take the following post to your pool guy and have him answer the questions, out loud, to you:

High Phosphates Over 1000 & Cloudy Water

Your alkalinity is fine, so don't touch that. I'd like to have your CYA. I'm hesitant to tell you to shock the pool with Dichlor because that's a stabilized form of chlorine. If the CYA range is between 30 - 50ppm, shock with regular liquid chlorine as per the yellow algae treatment found here:

Yellow Algae

The above link has a chlorine chart for your size pool. To raise a 10,000 gallons pool 10ppm, you'd use 3 1/4 qts. I'd go up to a gallon. It's better to go a little over than under. Keep the cartridges cleaned out the best you can. Once per day if you have the time. Lay off the phosphate remover. This cannot be emphasized enough. The chlorine kills the algae, and phosphate removers, only in extreme conditions, do nothing.

To post a reply, or if you have a similar question, you can see your post (Recurring Mustard Algae And Fed Up!) on the Q&A page in the "Yellow Algae" category.

Swimming Pool Questions and Answers

Check back to this post for answers.

Hope this helps and have a great Summer.


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Spa Has Algae But Pool Is Clear
by: Joan

I have had the same problem and spent 100's of $$ on algae treatment, phosphate removers, etc. I was told, if I used Phosfree, I would never have algae again. Lies!!! I have fought this for the past 3 years. Drained most of the water and re-filled the pool, shocked, chlorinated, etc. over and over. How do I control the stabilizer level? I noticed that most chlorine tabs have stabilizer. Is this something to avoid when using tablets? (I have a chlorine pool). I have a raised spa and it is yellow with algae but the pool is clean. Why does this happen? Thank you for your help!

Hello Joan. It sounds like your chemicals are messed up due to much misinformation that most pool owners get from the pool store. I need your complete chemical readings, the actual numbers:

Chlorine, CYA (cyanuric acid/stabilizer), pH, Alkalinity, Calcium Hardness, and Metals (iron and copper) and names of any algaecides you may have used along with clarifiers, phosphate removers, and/or flocs. It makes troubleshooting much easier and the process of clearing up your pool will go much faster. Green water is a symptom of the problem, not the problem itself. I also need the kind of filter you have and if it's working properly. If it's not working it must be fixed in order to clear up the pool.

What's happening is that you're being sold products that are marketed as "X" but actually do "Y". This causes bad results which ends up costing you hundreds, which you've already experienced. I've uploaded several detailed videos on my site and YouTube on clearing up and balancing green/cloudy pools. The normal time frame is about 3 - 5 days and $20 in chemical use per 10k gallons. If you're skimmer/pump baskets are clogged and the filter is nasty there's no amount of phosphate removers or floccs that will compensate for that. Let's get your readings and we'll go from there.

If you feel your situation is more complex than this, I do phone and/or SKYPE consultations. It makes things go much faster and many people have
found it extremely beneficial, saving them time and money in the long run. All your questions will be answered. I have nothing to sell you so you

know I'm not bias. If you purchase a personal phone consult you'll get all 3 eBooks for free.

Pool Consultation

Clear Blue Pool eBook

How To Clear Up A Green Pool eBook

Swimming Pool Resources


No More Money On A Swimming Pool
by: Robert

Thank Robert for you very quick reply.
What you're saying makes complete sense to me.

I was hoping that because I was using a local family owned pool store that I was getting honest answers. Very disappointing indeed. I can't afford to spend money on useless things.

I was trying to figure out what you meant by CYA and after reading into it a little more I see that it means stabilizer. Our pool tested at 50 which seems on the high side of what you said it should be.

The landlord said that they had $600 worth of work done on the salt generator before we moved in. The guy that was previously taking care of our pool said that he thinks it's not producing the chlorine that it should on a regular basis.

I'm going to contact the landlord and have him send someone out to take a look at it. Thanks again for all of your helpful information. You make pool care so much easier for us that are pool care challenged.

Thanks for stopping by and for the compliment Anita. I'm glad I could help and keep me informed. Best of luck with your pool.


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