Cold water & algae

Wayno

LifeTime Supporter
Aug 4, 2010
8
Central Fl
Morning all! Got a question for the forum experts. I am pretty convinced that I have been struggling with mustard algae for a while. It just looks like a stain on the walls. I've been maintaining a FC level of 10 - 12 with a CYA of 60. As long as the FC level stays up there, the stains are barely noticeable. However, when I get rain, I get a lot of organics washed down out of the oak tree above the pool, FC drops and the stains get darker.

My plan back in the summer was to wait until the water was too cold for swimming and take it up to MA shock level to try and get rid of it once and for all.

Now for the question. Will the combination of cold water (currently 62 degs) and FC level of 10-12 kill the algae over time? Or will it just go dormant and come back with a vengeance once the water warms back up?

As always, Thanks so much for this site and the helpful advice I've received!

Wayne
 

bk406

Well-known member
Dec 3, 2009
2,690
Central Massachusetts
The cold water will slow down the growth of the algea, but it wont kill it completely. At 60 ppm CYA, you MA shock level is 34 ppm. So even at 10-12 ppm FC, your not killing the algea. The cold water is most likely keeping the rate of algea growth low, but you still need to follow the CYA/shock level relationship regardless of water temp.
 

Ranger987

In The Industry
Nov 3, 2010
152
Does the stain brush off the walls? Mustard algae will brush off the wall pretty easily even though it's not dead and you will see a small cloud of it coming up as you brush. If it doesn't brush off, it may not be algae.
 

Wayno

LifeTime Supporter
Aug 4, 2010
8
Central Fl
Yeah, it brushes off. It's a diamond brite finish so I think the algae is imbedded in the rough texture. What prompted this question is that as the water has gotten colder, the "stain" has become less and less noticeable. As a matter of fact, I can't really detect it at all now. I guess I could let the CL level drop and see what happens.

Or, I could just go ahead with the MA shock procedure and hopefully be done with it. If that's the ultimate answer, is it better to do it now with the water cold, or wait until it warms up some?
 

Richard320

TFP Expert
LifeTime Supporter
Jan 6, 2010
22,069
San Dimas, CA (LA County)
If there's any chance it is algae, I'd shock it now. Shock it and then some, since nobody's swimming right now anyway. As soon as things warm up to some magic temperature, the algae's going to grow exponentially, and you'll need to buy exponentially larger amounts of bleach to kill it.

Forget the "until FC holds..." for now; just run it up to mustard shock level and a little beyond and keep it there for a couple weeks. Start the New Year off with a super clean pool. Then resume the usual maintenance. You'll know if it's gone, and still have enough time to try again before you want to actually go in the thing.

Just my opinion.
 

Wayno

LifeTime Supporter
Aug 4, 2010
8
Central Fl
Thanks, Richard. Thought I remembered someone stating that cold water would inhibit the killing potential of chlorine, but I tend to agree with you. Since if it is algae, and its compromised now, time to put my foot on its throat!!

FWIW, I've been monitoring the boards for a while now, and your opinion is one of the one's I would tend to pay attention to. Probably due to a shared affinity for a cold adult beverage :cheers:
 

paulsimmons

New member
Nov 30, 2010
4
I'd shock and throw in a bit of algaecide. Having dealt with algae that slowly grows through the winter months and then EXPLODES in the spring - I go with Richard and say do what you can to take care of it now. The headache on the other end will be huge!

I am curious about just "shocking" to kill the algae? I've never had success with killing any real amount of algae without using some other forms of algaecide like those. If that's common I'd appreciate a link to some information on it. I'll also be checking in the pool school.

Good Luck
 

257WbyMag

TFP Expert
LifeTime Supporter
Feb 23, 2008
5,061
Denton, TX
paulsimmons said:
I'd shock and throw in a bit of algaecide. Having dealt with algae that slowly grows through the winter months and then EXPLODES in the spring - I go with Richard and say do what you can to take care of it now. The headache on the other end will be huge!

I am curious about just "shocking" to kill the algae? I've never had success with killing any real amount of algae without using some other forms of algaecide like those. If that's common I'd appreciate a link to some information on it. I'll also be checking in the pool school.

Good Luck
Algaecide is never needed in a properly sanitized pool. It can also cause one to end up with more problems than they originally started with too. Depending on the type used, you can run into problems with metals such as copper which can stain pool surfaces and cause blond hair to turn green.

Whether you are choosing to shock now or shock later, the treatment will be the same regardless. Bring your FC to shock level based on the Chlorine CYA Chart and follow the instructions in Defeating Algae and you will remedy the situation completely and efficiently. It works every time.
 

chem geek

TFP Expert
LifeTime Supporter
Mar 28, 2007
12,083
San Rafael, CA USA
paulsimmons said:
I am curious about just "shocking" to kill the algae? I've never had success with killing any real amount of algae without using some other forms of algaecide like those. If that's common I'd appreciate a link to some information on it. I'll also be checking in the pool school.
Just shocking to kill algae works, but if your Cyanuric Acid (CYA) level is sky high it can take extraordinary amounts of chlorine so one is better off doing a partial drain/refill first in that case. See this link for an example of a pool with lots of algae upon spring opening (that was obviously "let go" over the winter) and how it got cleaned up using chlorine alone. We have dozens of examples of pools like this, mostly from new users who let their pools go, and they don't use or need algaecide to kill the algae. No algaecide will oxidize existing algae so even if some of them stop the algae from growing, you still need to get rid of the algae itself in some way.
 
G

Guest

Richard320 said:
Wayno said:
FWIW, I've been monitoring the boards for a while now, and your opinion is one of the one's I would tend to pay attention to. Probably due to a shared affinity for a cold adult beverage :cheers:
I think you're confusing me with Bruce...
Man, Bruce is getting a reputation, what a booze hound!
 

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