Mustard Algae - Nope it is scale instead (I think)!

[solardad]

(EDIT: So i updated the thread to better reflect the research and info from @zea3 in helping me diagnose this issue. still on going at the moment and I thought it would be helpful for others that may have a similar scenario.)

So a long time TFP fan and have 'adopted' the simple approach to pool management but I have crossed to the dark side a couple of times and this last time I think I have been caught. Sorry in advance for the length.

Background - Original owner of a 29k SWG pool for almost 11 years and for the 1st 4 years no issues. Year 5 or 6 had a bad algae bloom not sure if it was just green or combo with mustard but ended up using Yellow Gone with good success. Shortly there after found this site and started adopting the BBB method and eliminated all the 'extra' products with good success. Fast forward to this year's opening and disaster.

Now - Had my opening 7 days ago with the usual medium green sludge and did my opening steps to vacuum, balance and shock and the green water and junk was gone within 24-36 hours. Water clear and even some sparkle BUT I had stains, wire brush scrubbing didn't touch them. I'll call them stains but that might not be the best label but they are predominately in the deep end corners where there is shade for portions of the day and the shallow end for the most part is clear but still has some light staining. Since it is mostly concentrated in these shady areas my 1st thought is mustard/yellow algae (see pics).

My 1st step is to shock again, 20-25ppm for 24 hrs. no change and I soon confirm that my CYA is too high, 70-80. even after brushing there is no noticeable difference. Confirm that SLAM requires a lower CYA, 30ish, so I start lowering it with water replacement and then also realize that the kill level for mustard algae is 10-15 ppm higher than a normal shock so I decide to bit the bullet and load up on liquid bleach (10% concentrate) and shock at night to 50ppm. By then for this 3rd shock I had the following numbers prior to adding the bleach:

FC: 20
CC: 0
pH: 7.6
TA: 90
CYA: 50-60 (range since I am never 100% certain with the black dot just disappearing)
CH: 350
Salt: 3800

After this 3rd shock (get rid of mustard algae effort) I checked my FC levels the next AM, 12 hrs later, and my FC only dropped by 6-8 to 42-44ppm. Which is making me question my original thought that this is really mustard algae OR am I too eager in wanting a result?

(In the meantime my filter band broke and had to order a replacement so 2 days down - I know insult to injury going on here)

A couple days later I come across this video and think, "hey this is my issue and I'll follow this guy".

and use Yellowtrine. (When I did the application my numbers were the same except pH was: 7.4-7.6 and FC was 24.)

Now 24 hours later the stains appear to be the same and the pool has a slight green color and of course I now have bromine in the water, reflected in my pH test, coming up with a blue reading.

EDIT: I used 3 lbs. of Yellowtrine (1 bottle) and since my FC was already high 20+ I only used 9 gals of bleach vs 12 (package calls for 1 gal of bleach per 4 oz).

After all that I am looking for advice on what to do.

My 1st thought is to do another SLAM but get my CYA down and under 30 but I wasn't sure if I should try to get the bromine down which I think the only way is with water replacement. Would I be able to get it down enough while I worked on my CYA reduction efforts with water replacement?

Note - notice if the last picture from the deep end the leaf outlines where there is no algae growth. does that seem normal for mustard to not grow under a leaf or could that be a sign of something else like iron?

Thoughts..?

Thanks!

 

[zea3]

Hi, welcome to TFP! Yellow algae grows in shady areas and will brush off with normal effort. Have you at anytime in the past had a higher calcium level and pH over 7.6? I don't think you are looking at mustard algae problem. I am thinking you may have some calcium scale. As far at the Yellowtrine goes, the bromine content means you have converted your chlorine pool into a bromine pool. The only way to go back is to remove all the bromine contaminated water. You can run it as a bromine pool if you wish but we won't be much help to you in that case.
If you decide to drain and refill the pool we can determine if you have a scale issue and how to resolve it. Before draining the pool you need to determine how high the water table is in your area, what is your best choice for water to fill the pool (tap water if you have municipal supply, water delivery if you use well water) and how much you can safely drain without damaging the pool. We can help you determine the best course of action should you choose to drain/refill.

 

[solardad]

Thanks for the feedback.

In the past years pH yes but CH no, the highest it has been is the 400 range, but not this year for either pH or CH.

So when I look for calcium scale examples I am having a hard time finding similar pictures that match my scenario, most are crusty white along the tile line. Any examples that you can share?

Note - this is a seasonal pool that is drained roughly 50% every fall and then freezes over winter and is opened in May.

Edit - came across this thread and the issue sounds similar but no pictures to confirm. The poster though reported that it wasn’t until day 7 for results to start showing... Unable to get rid of Mustard Algae
Now wondering if I just didn’t wait long enough.. can mustard be that tough to remove..?


Thanks

 

[zea3]

Mustard algae brushes off. You said you have stains that a wire brush can't touch. Calcium scale on plaster looks mottled, and can be algae stained due to an algae bloom while calcium was falling out of solution and depositing on pool surfaces. I assume you drop your water level below the skimmer when you winterize? If so then the water was not high enough to deposit calcium scale on the tile over the winter when this probably occurred. I'll ask a couple of experts to look at your problem.

@JamesW, @jimmythegreek

 

[solardad]

@zea3 correct, I drop the level roughly 24” before I close. So hearing your explanation I think makes sense to me now after I did another test this afternoon.

I took a small pvc pipe and centered it over an easy to reach area that had a dark green spot amongst a general area of discoloration. I poured roughly 1/4 gal. of liquid shock (10%) down the pipe and waited roughly a min.. I removed the pipe from the floor and there was no change. After reading your info that result would now make sense to me since if the algae is covered by the scale then the shock has no way to reach it.

 

[zea3]

The problem I see is that you likely have calcium scale in a bromine pool. In a chlorine pool we would recommend you drop the pH to 7.0 so that the calcium will go back into solution. I'm not as familiar with bromine so I don't know if that will further complicate things. I'll try to get an answer. If you can move the calcium back into solution, then drain and refill that pool, we could get rid of your bromine and excess calcium at the same time.

 

[solardad]

@zea3 Thanks for your feedback here. I think I am resigned to the fact that I will need to swap out the water to truly get rid of the Bromine that I introduced.

I was thinking the same course of action that you mentioned above especially after coming across last night a number of posts on the site about the the 'no drain acid treatment' options. Seems like a happy medium to at least get rid of the scale without the time required to drain and refill. I'd be interested if others have feedback on the course of action.

As of now I am just waiting out the FC/Br levels to drop via the sun and have turned off the SWG. Water is mostly clear and I did do a small exchange last night to try and help out the effort.

The other thing that I wonder about is until I can set aside some time for the drain and refill can I just run the pool with my regular methods but with smaller amounts of FC given the Bromide Bank that I have there (my thought is that the triggering of the Bromide by the chlorine would assist with sanitizing and as a result you wouldn't need as much chlorine?). I know this is not an ideal setup but I am wondering how others dealt with this temporary scenario?

(Just thought I should try and update the title of this thread since mustard algae for the most part has been ruled out.)

 

[zea3]

You can give it a try, maybe look in the spa forum to see if there is any helpful info on running a bromine pool.

 

[JamesW]

Looks like copper, iron and scale.

The only thing that might get it clean is sulfamic acid (Jack's #2 copper and scale stuff) or a Zero TA treatment.

If you do either treatment, take the system offline during the treatment.

If it works, the copper and iron will still be in the water and they will eventually drop out as stains again.

The new stains might not happen for a year or they might happen in a week.

Draining and refilling would be the best way to permanently get rid of the metals as long as the fill water is not high in metal.

Draining can float a pool. So, consult a local professional to advise if draining can be done safely.

Do not drain without making sure that it is safe to do so.

Zero TA has some risks and you need to thoroughly investigate the process and risks to decide if the risks are worth the possible improvement.

The bromine and chlorine should be zero before beginning a zero TA treatment.