Question regarding Mustard/Yellow Algae

[garyengr]

A little over a week ago I began using the TFP methodology. Prior to this I was using 3" tablets and shocking approx every 2 weeks. I would get mustard/yellow algae occasionally on the walls, predominately the north facing wall but sometimes west and a little on the south. About 1 1/2 months ago I treated the pool with Yellow out. Since converting to TFP methodology, my pool water has been clearer. However a couple days ago as I was working on lowering my TA from 130 to 80 and as my FC approached 6.5 - 7 (CYA 70), I began seeing some mustard/yellow algae on the sides again. I have raised my FC to 13 to be above the 10.5 mustard/yellow algae target in the expanded table and after one day, I have not noticed any mustard/yellow algae on the walls. My overnight FC loss is < 1ppm, my CC is 0.5 and my pool is clear.

My questions:

(1) Should I do a mustard/yellow algae shock? If so, do I perform the algae shock before since I already pass the criteria for stopping.

(2) If I just keep my FC at or above the mustard/yellow algae target, will this prevent mustard/yellow algae returning? After a period of time at the mustard/yellow algae target, will I be able to lower my FC to the normal targets w/o mustard/yellow algae returning?

Current pool chemistry is:

FC: 11.5
CC: <0.5
CH: 200
TA: 115
CYA: 70
PH: 7.5

Thanks,

Gary

 

[Richard320]

Actually, shock level for 70 CYA is 28 FC. Mustard shock level is 39

I'd suggest you raise FC to 28 or a little better, let it mix a while, then test it before bed and run the overnight loss test again in the morning. If it still passes, then add the rest of the bleach to take it up to Mustard level. Don't neglect to brush everything and toss the toys in as well, as mentioned in http://www.troublefreepool.com/content/148-mustard-algae

 

[garyengr]

Actually, shock level for 70 CYA is 28 FC. Mustard shock level is 39

I'd suggest you raise FC to 28 or a little better, let it mix a while, then test it before bed and run the overnight loss test again in the morning. If it still passes, then add the rest of the bleach to take it up to Mustard level. Don't neglect to brush everything and toss the toys in as well, as mentioned in http://www.troublefreepool.com/content/148-mustard-algae

The 10.5 I referred to was the Mustard/Yellow algae min FC in Chemgeek's table. Was hoping that was sufficient. However, will perform the SLAM per your recommendation.

That said, what is the Mustard/Yellow algae min in Chemgeek's table for?


Thanks

Gary

 

[Richard320]

The 10.5 I referred to was the Mustard/Yellow algae min FC in Chemgeek's table. Was hoping that was sufficient. However, will perform the SLAM per your recommendation.

That said, what is the Mustard/Yellow algae min in Chemgeek's table for?


Thanks

Gary

I'm not sure!

I suppose you could always PM him and ask, This chart, right? http://www.troublefreepool.com/threads/2177-Chlorine-CYA-Chart

 

[garyengr]

I'm not sure!

I suppose you could always PM him and ask, This chart, right? http://www.troublefreepool.com/threads/2177-Chlorine-CYA-Chart

That's the one. BTW - use to live in Alta Loma. Talked to an old friend in Upland - boy you guys have it tough with the water situation. When we live in Cal. use to get 20" of rain. My friend told me they haven't gotten 5" in Upland - we will beat that in the desert here in Tucson.

 

[garyengr]

Took it to 33 at 6:00pm, it was still at 33 at 6:30 am with CCs at <0.5. Brush sides (noted slight yellow cloud at some spots on first brushing) and vacuumed the pool several times.

Raised FC to 45 (40.5 + some margin) at 7:15am. Brushed the sides (noted nothing came off the wall). Tried to remove light fixture. Was able to get the screw out but haven't been able to get the fixture out. Should the fixture tilt out or is it necessary to rotate to remove?

 

[Richard320]

Took it to 33 at 6:00pm, it was still at 33 at 6:30 am with CCs at <0.5. Brush sides (noted slight yellow cloud at some spots on first brushing) and vacuumed the pool several times.

Raised FC to 45 (40.5 + some margin) at 7:15am. Brushed the sides (noted nothing came off the wall). Tried to remove light fixture. Was able to get the screw out but haven't been able to get the fixture out. Should the fixture tilt out or is it necessary to rotate to remove?

Yes.

Sorry, can't tell exactly how yours comes out without looking at it. Typically, it tilts out wherever the screw was holding it.

 

[garyengr]

Yes.

Sorry, can't tell exactly how yours comes out without looking at it. Typically, it tilts out wherever the screw was holding it.

Finished Mustard/Yellow algae shock and passed all three criteria this morning. Have not been able to remove light fixture - have screw removed but tried prying and rotating to no avail (hesitant to put too much for and might bend the stainless steel ring). Working from above is awkward as I have to stretch to reach. Plan to continue one more day of Mustard/Algae level shock (FC>40.5) and have injected Chlorine into the crack and holes in the fixture as best I can. Here is a picture of the light if that helps:

 

[duraleigh]

That ring is normally held on with a single brass screw at the dead center top hole......it's pretty small. Once that screw is out you should be able to pry a little back and forth and it should come right off........unless someone has decided to give it "extra" security.

 

[garyengr]

That ring is normally held on with a single brass screw at the dead center top hole......it's pretty small. Once that screw is out you should be able to pry a little back and forth and it should come right off........unless someone has decided to give it "extra" security.

Thanks. The screw was about 10 to 15 degrees to the right of top dead center (you can see the hole in the picture) and was stainless steel. You would think they should be able to put the niche in better than that or they did something screwy when they installed it. I will need to be in the pool to exert any force on the ring. I'm almost falling in when I reach from above and I am 6' 1'' tall. I will get in and work it when the pool warms up - been running 70 degrees due to our cold front that moved through here - was nearly 76 a week ago.

 

[chem geek]

That said, what is the Mustard/Yellow algae min in Chemgeek's table for?

That is the minimum FC required at the associated CYA level to prevent yellow/mustard algae from growing. Yellow/mustard algae is more resistant to chlorine than green or black algae. Because that minimum FC/CYA ratio is about double the normal ratio, it would be more expensive to maintain the pool to prevent this algae growth. This is why it is generally better to try and eradicate this algae completely, but that is not always possible because it can get reintroduced if you are near an area (such as a lake) with this algae.

If you are unable to eradicate the algae, then there are last resort methods that will prevent the algae growth and let you maintain more normal FC/CYA levels. Keep us posted with your progress.