Mustard algae treatment without chlorine?

[Jaywalker]

I'm starting to see indications of mustard algae on the sides of the pool. What are some ways to get rid of it with inadequate chlorine supplies?

Answers that increase the CYA will be okay as I'll drain/refill as necessary.

I'm not quite ready to treat for mustard. The overnight chlorine drop test shows 0.5ppm drop, so I might be wrong about it, but it pays to think ahead so I'd like advice on treatment if I need it. So far, I'm keeping the pH lower than normal to allow the chlorine I do have to work more efficiently, and I'm running the sheer falls a little more than normal to have aeration assist, also, along with more frequent brushing.

Alternatives to chlorine shock?

 

[HermanTX]

You would want to use Liquid Chlorine to bring your FC levels up quickly. You do not need granular shock or tablets.
If your OCLT was only 0.5, then do you have visible algae on the walls?

Keeping your pH low but running the sheers more will actually increase your pH so not sure why you are doing that.
What is your CYA as that will dictate how much rise in FC you will need to do. Normal SLAM requires your FC to be 40% of CYA and Mustard Algae requires your FC to be 60% of CYA. This are estimates and best to consult with the FC/CYA Levels

 

[Jaywalker]

Thanks. I'm aware liquid chlorine is preferred, but as I mentioned chlorine is unavailable and I'm looking for alternatives. Also as I mentioned, "aeration" is a well-known way to help treat water, and since I don't have a fountain, the sheers must serve, even though they increase the pH. Muriatic acid is available, so I add more of that to counteract the waterfall effect.

Are there any alternatives to liquid chlorine?

 

[Newdude]

Are there any alternatives to liquid chlorine

In short, no. You can buy stabilized chlorine (granular/pucks) which are bound by either Calcium or CYA. Either of those options will raise your levels and you must keep a close eye on how quickly they do. Both also seem to be in short supply this year.

If you were to have an Ozone system, it would treat the water passing though the unit but leave the 99.99999% of the pool untreated. You cannot replicate this process with return jets or waterfalls, etc. you need the actual unit and you’ll still need full residual chlorine added with liquid or pucks/granuals.

The only way to add residual sanitizer without physically/literally adding a form of chlorine yourself is to convert to Salt and get a SWG. The SWG will convert the salt content to chlorine gas to treat the water. Ironically here you’d still be adding chlorine, but the unit would be doing the leg work for you as you sipped lemonade and otherwise enjoyed your day doing other things.

 

[Jaywalker]

Thanks. I have considered a SWG and may do that, but I've had long reservations about using it with sandstone coping, given out really hard water.

 

[Newdude]

but I've had long reservations about using it with sandstone coping, given out really hard water.

Again. A total misconception. If any materials used outside are not of durable quality, they will not last due to moisture. A liquid chlorine dosed pool will be around 5% of seawater and a ‘salt pool’ is 10% of seawater. Some members have even had to drain when they switched as their salt level was too high already. But if they had stone erosion it would have been blamed on the salt. It’s the stones fault and it will happen either way.

 

[Jaywalker]

Nice to hear. Would it be advantageous to have the sandstone coping sealed every year or so? BTW, I'm brushing and vacuuming sandstone off the bottom, anyway.

Then all I have to worry about is SWG shortages...

 

[Newdude]

Would it be advantageous to have the sandstone coping sealed every year or so?

Yes. But it’s usually expensive so many folks don’t and just let the weathered stones run their course before replacing it all.