FC not reading properly?

DougFL

Active member
May 31, 2024
26
Milton, FL
Hi all,

I am in the midst of attempting a Mustard algae SLAM but am not able to even get through the initial SLAM because I am not able to get a proper reading on my FC. My test results are below before I get into this:

FC: 11.5
CYA: 70
TA: 80
PH: 7.5
CC: 0
Calcium: 90

So, my wife and are are in our 2nd season with our pool and have been correcting major chemistry issues from the first season due to our lack of knowledge during our first season (feeding the pool trichlor pucks, not maintaining chlorine well, not cleaning enough etc) and this is why some of our numbers are a little high. We have slowly been draining and refilling and balancing chemicals using the TFP method. Things seems to be coming into balance but a few weeks ago we noticed what we thought was dirt and have now realized is mustard algae. Without doing a mustard SLAM yet we have mitigated it some by using skimmer socks, backwashing the filter and creating a vacuum with our hose using gravity so when we suck out the mustard algae the water just flows into the yard. That has helped actually quite a bit but we are not able to do a proper SLAM because I am not getting a clear FC reading with my Taylor 2006C kit. Our water is crystal clear, CC is 0 but it seems that when I test FC I cannot get a clear reading when the FC is above 17 or so. When the level is 17 or lower and I am adding my 0871 I can get the test water perfectly clear but when the levels go above 17 it always has a slight pink tint to it and I cannot interpret it properly. I have went as high as using 100 drops of 0871 to see if that pink tint would go away and it does not and so I cannot tell what my FC is. I store my test kit indoors at 73 degrees and none of my chemicals are expired. I am a little confused and would appreciate and feedback you may have.

Also, my high FC reading of 17 is because I have attempted a SLAM and realized I am not able to get a good reading so I have let the FC level drop so I can get a reading and then raise it back up to attempt another reading and this is when I figured out I can only seem to get accurate readings under 17ppm and not above that. I have since tested with these levels 4 more times and have come to the same conclusion each time.

Thank you- Doug
 
I forgot to add that I had initially brought my PH down with MA to 7.2 before attempting the SLAM but it has since crawled back up with having higher FC levels.
Got a picture of what the sample looks like after adding the 34 drops that equate to 17ppm FC?
 
I see the instructions can have you test using either 25ml or 10ml of water, depending on the precision you want. But then they say to add "2 dippers R-0870". Others with more knowledge can chime in, but I wonder if using the 10ml amount, you should only use "1 dipper". That's what my TF-100 Pro calls for, which I believe is basically the same kit.
 
I don't. It is hard to capture the subtleness of the pink enough to highlight it. It is most noticeable when viewed from the top but it isn't there when FC is under 17ppm.
Ive been here for a few years and thats the first Ive heard of that problem. Do you have speedstir? A picture would help.
 
I am sure this is a redundant question here in the forums but I am just looking for a little reassurance. I live in NW Florida, just outside of Pensacola and it has been a hot year. About one month ago spots appeared on the bottom of my pool. I assumed algae as it turned into a light green cloud when I would brush it or even pass near it underwater. It seemed to accumulate quickly when I did not brush the pool for a few days and then I figured it was mustard algae based on posts I read in TFP forums. My skimmer socks were yellow, which reinforced the idea of mustard algae, but I noticed that the presumed mustard algae was only on horizontal surfaces and not vertical surfaces like my pool walls or the vertical parts of my pool stairs. I scrubbed and vacuumed the pool, cleaned ALOT of yellow out of my filter cartridge and made sure my FC was in range and the dusty mustard algae appears less but still appears. My water is crystal clear, my CC is 0 and I passed an OCLT so I am wondering if it is possible if this really is just pollen, and this late in the year?

Any thoughts are appreciated,

Doug
 
There always seems to be a fine layer of either dust or pollen on our deck and furniture but nothing like the yellow pollen of spring. I am just confused by passing the 3 criteria of clear water, no CC and passing an OCLT, as well as the TFP article that states mustard algae likes growing up walls and I have not had that.
 

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This is mustard algae.

You can pass an OCLT with mustard algae.

There are two types of mustard algae.

You have the common yellow mustard (French's) and the much less common Grey Poupon mustard, which is more of a green/brown/yellow color.

The common type gets on all surfaces.

The uncommon type sits on the floor like sand.

1723434845743.png
 
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Please do not make new threads on the same issue because you lose continuity.
 
I'll take pictures in the morning and post them. Regarding what you just said about passing an OCLT with mustard algae, is it worth it for me to bother taking my morning FC reading as I was attempting another OCLT?
 

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Thank you James. I couldn't get a clear picture today so while cleaning this morning I put on my goggles and went down to the spots on the bottom and they were clearly sand. I felt them and they were grainy and when disturbed you can clearly see the sand grains floating off. I have not actually seen the mustard algae in about 3 days now since starting the SLAM. All 3 criteria have been met for completing a SLAM as we passed the OCLT last night with no FC loss.
 
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Hi James, I attached 3 images of the stuff I am seeing in my pool and was hoping you could give me your feedback. The spots often appear in the crevices as I am sure you know, and I also collected some in a jar and took a close up. To me it looks like grains of sand but who knows. I will see if it grows tomorrow and go from there. Please let me know your thoughts. Thank you - Doug
 

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I can't really tell exactly what it is.

It does not look like mustard algae, but it might be.

Mustard usually is an olive green with hints of yellow, green and brown.
 
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