Killing mustard algae

[FlpoolRob]

I'll start off with my stats:

FC: 45ppm
TA: 75ppm
CYA: 70ppm
pH: 7.2
CA: 300ppm

So I started by slamming the pool and held it until it passed the OCLT. Then I raised it up to the mustard algae level. It's been at that level for well over 24 hours and its not passing the OCLT. Does this mean I'm still killing algae? Or is there some other mechanism that can cause chlorine levels to drop when at a high concentration?

I'll also say it is definitely mustard algae. It was a yellow orange color. It was inside the covers to my pool lights and along the floor on the south side of the pool.

Also, it's a SWCG pool and I have no CC.

 

[RobbieH]

If you are performing the OCLT properly, you should be able to pass. It is important that the first and second tests are taken when the sun is not out.

How much are you losing on the OCLT?

 

[FlpoolRob]

I lost about 4.5ppm last night. The 2 measurements were taken at 11:30PM and 7AM. The sun was coming up, but the pool was not in direct sunlight yet. Does that matter?

 

[imwarren]

for you to loose 4.5 you have to be killing something. Keep at it. make sure any non-human/ animal objects that will be going in the pool are put in while it as at the mustard levels. Solar covers floats toys hoses lights dive sticks snorkles gogles you name it,
get it in there or do a seperate chlorine bath on it.

 

[jblizzle]

While in the SLAM process, did you pass all 3 criteria prior to raising to mustard algae SLAM level?

 

[FlpoolRob]

While in the SLAM process, did you pass all 3 criteria prior to raising to mustard algae SLAM level?

Yes

 

[jblizzle]

I do not recall seeing this reported before ... wonder if you got a "false" OCLT pass before

Solution is just to continue to maintain until you pass at least once more.

 

[imwarren]

This is normal for mustard algea the regular slam level will not be affected by it so you will pass the regular onclt but once you raise to mustard levels it gets used so keep at it this is tgeonly way to get it all

 

[foobert]

I had the same thing happen when I took mine up to full mustard strength. Keep at it till it passes.

Be thorough and diligent, and you'll get it. Keeping my fingers crossed that I never see it again...

 

[FlpoolRob]

Thanks for all the help. I was starting to worry I was leaving it at high CL concentration for too long, as I am going into my 4th day at 45ppm. Hopefully it will get there tonight.

 

[FlpoolRob]

Dang. Failed again this morning. I lost 9ppm FC last night. I've gone through 14 gallons of CL for a 12,000 gallon pool so far and I'm on day 5 of this. I HATE mustard algae.

 

[chem geek]

If your filter is dirty, it could contribute unnecessarily to the overnight chlorine loss, though usually wouldn't be seen unless your pump was running at least part of the time overnight. You might take a look at it. If you have your lights out to expose the light niche or other areas that you've newly exposed to direct high chlorine levels, you might physically clean them out to accelerate the process.

 

[FlpoolRob]

I have been running the pump 24 hours a day during the process. Should I not be running it? I also cleaned the filter right before I started slamming. I did scrub around the lights, cleaned the light covers, put all the pool toys and floats in the pool yesterday around 5PM. Maybe that extended it. I've gone through about 14 gallons of chlorine so far and it looks like probably a couple more today to cover sunlight loss. Hopefully tonight's OCLT passes.

 

[DorsalSpine]

I have been running the pump 24 hours a day during the process. Should I not be running it? I also cleaned the filter right before I started slamming. I did scrub around the lights, cleaned the light covers, put all the pool toys and floats in the pool yesterday around 5PM. Maybe that extended it. I've gone through about 14 gallons of chlorine so far and it looks like probably a couple more today to cover sunlight loss. Hopefully tonight's OCLT passes.

Yes you should be running the pump 24/7. You need to keep an eye on filter pressure. If it jumps up you need to clean the filter. Some people dump to waste so they don't have to kill the algae trapped in the filter. If your filter is full of algae your water may be clear but you don't pass the OCLT because you are still killing the algae trapped in the filter.

 

[FlpoolRob]

Alright. I think it passed this morning. My first test didn't, but I always do it twice for sanity. It seems you can not put enough dpd powder in the sample or something. Anyway, second test showed a 1ppm difference and less than .5 CC. I'm going to clean the filter again this morning as insurance just in case. Thanks for all the help.

 

[imwarren]

If you lost 1 ppm I would keep it up one more day likely try to get it close to 0. Mustard algea suck I tried 2 years before I finally unnderstood how tough it is and made sure I followed throiugh until at Mustard slam level It passed each of the 3 criteria perfectly not just withing recommendations. I was crystal clear 0 fc loss and 0 CC till I quit and now I havent had mustard algea for over 2 years It took me 5 days a mustard levels to get there but it is the only way.

 

[Butterfly]

I did scrub around the lights, cleaned the light covers,......

Did you remove the light from the niche and check/brush inside?

If you did not, I suggest now is the time to do it while it can be exposed to the high FC.
Turn off power/breaker first.

 

[FlpoolRob]

My lights don't come out of there niches. I have LED lights. They are screwed in with an oring to protect it. I would have to drop the pool level to open them up.