Mustard Algae?

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AimeeH

AimeeH

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TFP Guide
Apr 2, 2012
2,021
Columbia SC
I fear I may have mustard algae. I have this spot on the floor where it meets the wall on the side of the pool that gets afternoon shade (west). It is yellowish green. The first time I noticed it I brushed/vacuumed etc. and it went away. Now approximately a week or two later it is back in two spots on the same area of floor. My chlorine has remained between 4.5-7.5 (varied because trying to adjust SWG)since opening this season. After the first time I noticed this spot I did OCLT and have never lost even 1 ppm chlorine overnight. Last OCLT was 0 loss (last weekend). Water has been clear all season (still is) Could this mean Mustard algae? If it is I know I will need to raise chlorine to mustard algae shock level. I've never used any chemicals besides salt/MA/CYA/Borax since the pool was installed and initial treatment by builder in 2011. It seems like this would be ALOT of bleach to raise to mustard algae shock level so my question is if I should use cal-hypo instead since CYA is good(I have no experience with these pool chemicals). I have only tested CH once since it is a vinyl lined pool and I tested 30 (I will double check this).

Todays numbers (tf-100)
FC-7.5
CC-0
PH-7.3/7.4 (hard to tell exactly)
Borate-30
TA-77
CYA-70(ish...cloudy day but consistently dot has disappeared between 60-75 since 5/24/2013)
Salt 2980
CH-30 (5/27/2013 will check this again)

I know everything that I know about pool care from this site so will follow advice given (sorry if I left out any detail). Found this site shortly after install in 2011 and have never had a pool store test my water or sell me chemicals........but now my worst fear is mustard algae :cry: All advice welcome.
 

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With a SWG the FC should stay at 3 unless your are completing the shock process. Since you have been higher than that I am thinking the algae is growing in an area of poor circulation. Even though you are passing the overnight test, you should go ahead and complete the shock process.
 
Thank you. I have seen sort of conflicting information on chlorine levels with SWG. I know it is ok to stay lower than with regular chlorine pool but chlorine/cya chart says target should be 5 with my cya of around 70 so I guess I've been error ing on the high side.

Also from all my reading about mustard algae it sounds like a nightmare to defeat and I have no idea how to remove and clean lights. And considering clear water and passing OCLT should I just immediately go to mustard shock level? What would be easiest to use chemical to get it there since lugging that much bleach is very unappealing to me.

Anyone else know if these look/sound like symptoms of mustard algae?
 
Any chemical advice that may be easier than bleach before I head 20 miles into town? Am I correct in thinking I can use cal-hypo since my ch is so low? Are there any other adverse affects of that product?
 
AimeeH said:
Thank you. I have seen sort of conflicting information on chlorine levels with SWG. I know it is ok to stay lower than with regular chlorine pool but chlorine/cya chart says target should be 5 with my cya of around 70 so I guess I've been error ing on the high side.
You are correct that 5 is the target for CYA of 70 with SWG. 3 is the dead low minimum.
Also from all my reading about mustard algae it sounds like a nightmare to defeat and I have no idea how to remove and clean lights. And considering clear water and passing OCLT should I just immediately go to mustard shock level? What would be easiest to use chemical to get it there since lugging that much bleach is very unappealing to me.


Anyone else know if these look/sound like symptoms of mustard algae?
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Mustard Algae disappears at normal shock levels only to reappear when FC drops back down to normal range. You should follow the Shock Process in Pool School. That is the FIRST step. After you are done shocking, (passing the three tests) you can then take it to mustard algae level for 24 hours. In the meantime, check every nook and cranny for algae hiding.

Liquid chlorine/bleach is the best for the job. That is a lot to haul, given the size of the pool and the CYA level. You might shop around for higher % liquid chlorine. Also, if price was no object, there is always Lithium Hypo - A convenient powdered form of chlorine. Like liquid chlorine, it doesn't add anything that will cause problems to the water. However, it is generally far more expensive than any other form of chlorine.
 
If it is yellow/mustard algae, then you'll need to look in other places in the pool it can hide out such as behind light niches, under removable ladders, etc. Otherwise the shocking may not completely kill it off and it will come back. Be sure to put in poles and other equipment you use into the pool while you are shocking it. With this sort of algae, it's all or nothing.
 
First off I want to thank those for responding, I love this site.

I have never shocked my pool since finding this site shortly after build so this "possible" mustard algae has me in a panic. I've read pool school probably 100+ times since 2011. I've been maintaining my pool with SWG and BBB pretty much since the beginning. In this climate we run the SWG and pump all winter but less hours in a day.

The first time I discovered this stuff (same area as now) I brushed and vacuumed. I did OCLT at that time (water always clear and cc was zero) and I showed 0 chlorine loss overnight so I figured I was fine. Now a week and a half later the greenish yellowish stuff has reappeared. I was thinking that I could go straight to mustard shock since essentially all three tests have passed?.....just not today. As of today water is still crystal clear and cc 0.

1.Could it even be mustard algae if I passed OCLT? after vacuuming the area last week?
2.Should I do OCLT again tonight before going through shock process (since cc is 0 and water is clear)
3. I suppose this could be pollen?but we are way past our horrible pine pollen season so I'm not sure what kind of pollen

I'm frightened that it could be mustard algae.
 

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chem geek said:
If it is yellow/mustard algae, then you'll need to look in other places in the pool it can hide out such as behind light niches, under removable ladders, etc. Otherwise the shocking may not completely kill it off and it will come back. Be sure to put in poles and other equipment you use into the pool while you are shocking it. With this sort of algae, it's all or nothing.
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yes.....I've read all the instructions many times and will follow to a "T" but I fear all of this because I don't know how to remove and clean light niches? we have two lights one in the deep end and one in the shallow end. We have no ladders so I wasn't worried about that.
 
Before you go through all this trouble, you should make sure it isn't something simple like pollen. Usually though pollen will settle in seams or where circulation tends to deposit dirt and other physical material. It won't usually congregate just on the shady side of the pool unless that's where circulation tends to dump things.

As for the light niches, I'll let others walk you through that -- I just had my lights replaced as they had burned out, but had an electrician do it and I have a plaster pool so different than yours (I'm not sure how lights are done in vinyl pools -- I would guess with a similar niche, but there must be some seal of the vinyl and the light or niche).
 
Thanks Chem Geek.

How do I determine if it is just pollen?

OCLT again?

when we touch it it doesn't feel like anything at all (not slimy not gritty according to hubby). Previously wiped it with a white t-shirt and it was pretty green out of the water. When wiped with a hand it disappears. It is in an area of poor circulation as far as I can tell since this would also be where sandy dirt collects. By appearance it "looks" to me above the water that it "may" be a tiny tiny bit up the side.....maybe I need to get in with my goggles and double check that?

Obviously I'm in a bit of a panic here. I made the cal-hypo purchase and am standing by (cal-hypo because it was easiest to find and didn't want to deal with 2000 oz of bleach and my ch is about 20)
 
Just went out and looked again and it definitively appears to me to have gone slightly above just the horizontal floor (as in creeping up) which would indicate algae correct? Again CC is 0 and water is clear.

tried to upload photos but named files wrong
 
Pics....hopefully the correct ones this time. This stuff does not seem to be evenly distributed like our spring pollen is :(
 

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Thanks Butterfly. I just checked again and FC is 6 and CC is still zero (water does not turn pink when 5 drops of r0003 is added) was 7.5 this morning when SWG is running. I will proceed to shock level. Should I run pump then for 24 hours and wait until tomorrow night for OCLT?
 
I have added 112 oz of cal-hyp to bring FC up to 20 and turned off SWG. Will brush and running pump will check FC in an hour or so. I'm happy to have this place holding my hand as in 2.5 years I've never had to shock before. I have turned off SWG so I can check OCLT tonight.
 
I have some questions. What size pump do you have? What type filter do you have? How forceful does the flow feel from the returns? When was the last time you cleaned the pump strainer pot? When was the last time you cleaned the filter?
 
zea3 said:
I have some questions. What size pump do you have? What type filter do you have? How forceful does the flow feel from the returns? When was the last time you cleaned the pump strainer pot? When was the last time you cleaned the filter?
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ok....I think I have this correct. pump is Hayward 1.5 hp. filter is sand. I have never cleaned the sand. Build was done in late July 2011. SWG is pentair. Pump pressure is 12 psi at all times. I backwash often (maybe too often?). We have had to remove (backwash) water a bunch this year with so much rain. Because of rain I've stayed on top (I thought) of my water balence......bumping up chlorine output before storm etc.

I have two skimmers and 8 returns. Two of the eight returns are 1.5 inch threaded pvc. The other 6 are "eyes". The flow is forceful (seemingly same as it was right after build) out of all returns. There are two "eyes/jets" at the deep end swimout steps.....visible in pic posted of "clear water"......although pump was not running at time of photo.

edit.....filter pressure not pump pressure is 12 psi

This area where I think there is algae has the poorest circulation.....I know because that is where there is always dirt build up settling.

We clean out the basket at the pump on a regular basis (weekly?) when there is visible debris.
 

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