Suspecting mustard algae.

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Jennica

Jennica

0
May 24, 2012
98
NJ
I did a SLAM last week because water was cloudy and there was some visible algae on the shady side of the bottom and on the ladder steps which are also shaded. I SLAMmed it for a few days with no improvement so I bumped it up to Mustard Algae SLAM level. The water instantly cleared, the filter cartridge was clean, I passed the overnight test and I thought I was home free so I let the FC drift down.

Today the water looked a tiny bit cloudy again so I checked the filter cartridge and sure enough, it was full of bright green algae. Does bright green algae indicate mustard algae? Might be worth noting that at no time during either SLAM did I have significant chlorine loss. I was basically topping it off a few times per day to bring it back up to SLAM/MA level. I had .5 or less CC the whole time and never lost more than 1ppm per night. Most nights I lost zero.

I have brushed daily, removed the solar cover, and checked everywhere for hidden algae. There aren't many places for it to hide, although if the consensus is that it's not mustard algae, I will remove the ladder and see if there is any hiding inside. This is a last resort because I have the outside steps of the ladder dug into the ground a few inches and am dreading taking it out. I will if I have to though.

FC - 12 (Have since brought it back up to MA level of 24)
CC - .5
PH - 7.2 (Been keeping it low because I did the Metal Stain Removal thing a few weeks ago.)
TA - 100
CYA - 40

Thanks!

*Edited to add another potential clue. This situation has happened to me two times before and in all three instances the algae started after returning from being away for a few days. While I was away the FC never got down below minimum level. In fact, it was well above.
 
I copied this directly from the article on mustard algae:

It tends to grow in clumps on surfaces at normal chlorine levels, and varies from a true "mustard" yellow to green with hints of yellow. It can also grow free floating in the water if the chlorine level is low enough.

Most people who think they have mustard algae don't actually have mustard algae. Pollen is often mistaken for mustard algae, since it often collects in very similar looking patches. Mustard algae tends to grow on the walls and floor of the pool on the shaded side. Pollen can look very much like mustard algae, but it will only settle on the bottom of the pool, not the walls, and appears everywhere, not just on the shaded side. Another way to distinguish between the two is that when you go up to shock level and brush the pool, mustard algae won't come back as long as you stay at shock level.

If you suspect it, go ahead and SLAM at mustard algae level...if it is MA you have to get rid of it, if it is not MA, you will get through your SLAM a little quicker. Make sure you pass all criteria for SLAM 1) crystal clear water 2) pass OCLT 3) no CC's
 
Thanks for the reply.

My problem is that I passed all the criteria and thought I was done with the SLAM. It was when the FC drifted back down that the algae came back. Water was crystal clear, I passed OCLT, mostly had zero cc (never more than .5). I had it at MA level for 48 hours. Should I hold it there for a few days after passing all the criteria?

Does the fact that the algae in the cartridge is bright green mean anything? It's pretty bright. Much brighter than any algae I've ever had before.
 
It means you have algae, regardless of the color and you need to SLAM it hard. You have done well understanding the SLAM process. SLAM it at mustard level and you will either get done with the SLAM quicker if it is regular old algae or you will have taken care of the mustard algae if it proves to be that. People freak out over mustard algae...algae is still algae and you have to attack it. The only kind of algae I get is mustard algae because my pool likes it and I just have to SLAM at that level. Good luck! SLAM hard, brush often and keep us posted!
 
Also be aware that if you are reading your CYA incorrectly, you may be keeping your FC too low for your CYA and letting regular algae return. I know this from experience since I thought my CYA=50 when it was actually CYA=70. See post:

https://www.troublefreepool.com/threads/146104-CYA-50-Standard-Go-Bad

I highly recommend purchasing the CYA Standard from TFTestkits (if you haven't already), just so you can see what the end results of the CYA test should look like. I was surprised to find that the end result was not that the dot was no longer visible, but that the dot was barely visible. That was a difference of 20ppm!

Just a thought...
 
OTPirate said:
It took me 3 full days to pass my SLAM with MA, and I did keep my CL at MA level. Every SLAM is different as every pool is different. Post pics if you can.
Click to expand...

Good to know. I'll keep at it. ;)

Holydoc said:
Also be aware that if you are reading your CYA incorrectly, you may be keeping your FC too low for your CYA and letting regular algae return. I know this from experience since I thought my CYA=50 when it was actually CYA=70. See post:

https://www.troublefreepool.com/threads/146104-CYA-50-Standard-Go-Bad

I highly recommend purchasing the CYA Standard from TFTestkits (if you haven't already), just so you can see what the end results of the CYA test should look like. I was surprised to find that the end result was not that the dot was no longer visible, but that the dot was barely visible. That was a difference of 20ppm!

Just a thought...
Click to expand...

Interesting. I have been using up last year's CYA reagent, consistently got reading of 40. I just cracked open a new bottle and got a reading of 50. Thanks so much!

I bumped the chlorine up to MA level for 50 CYA. I'm still thinking it's mustard algae because I've been keeping chlorine at 24 for a few days now, which should have been high enough to kill regular algae. I'm a little worried about my liner, but I'm so ready for this SLAM to be over.
 
Found my algae hiding spot. The styrofoam on my weir flap was falling apart so I took it off to replace it and there's was bright green algae under it. And this was after finishing a SLAM. I bet the algae would have come right back again once the FC level drifted down. I never would have thought to look there if the styrofoam wasn't breaking down.
 
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