Mustard algae not much affected by shock

[Noorm]

Every day, when I brush, I see small clouds come off the wall, leaving the stains behind. Even though FC is at 33, and Ph at 7.2 it keeps coming back. The stains are kinda scaly looking, and I suspect they will not ever go away.
Also I'm uncertain about testing with the K-2006 kit:
The disappearing black spot is sort of imprecise. When I perceive it to be gone, tube is below the 100 line, so I'm guessing about 110. When I test with strips I get 50-100.
Also for the alkalinity test it says count drops til it turns from green to red, but it only gets to a yellow tint, and after that no change when additional drops are added, if I just base reading on when the green fades to yellow, alkalinity is around 90. Are Taylor's instructions for color change a bit inexact?
Any insights will be appreciated. I just started taking after the pool when the chemical service I've used for 25 years lost control of the algae.

Thanks,
Noorm

 

[jblizzle]

Welcome to TFP!!!

First, forget the test strips. Second, with the CYA test below the line, that means the CYA could be VERY high ... it is logarithmic. Try the diluted version of the test described in the Extended Test Instructions.

BTW, if you CYA is 110ppm (doubtful), then shock level is a FC of 39ppm ... and for mustard (which I would not assume at this point) the FC level is 54ppm This is why your first step should be to replace water to get the CYA to a reasonable level.

The TA colors get skewed at high FC levels ... that is why you see yellow. This is also described in the link above.

 

[Noorm]

Thanks for the help Jason. Can you elaborate on your comment "and for mustard (which I would not assume at this point) "?

 

[JasonLion]

Your description does not really fit the standard mustard algae description. Plus you whole problem is explained by the very high CYA level. So it is very doubtful that you will need to follow the special procedure for getting rid of mustard algae.

 

[Noorm]

Your description does not really fit the standard mustard algae description. Plus you whole problem is explained by the very high CYA level. So it is very doubtful that you will need to follow the special procedure for getting rid of mustard algae.

OK, rechecked CYA with alternative test and got a reading of 60, so I added chlorine to raise ppm to 30. The stuff on the wall looks better , but still seems to be "growing" between brushing.
If this isn't mustard algae, what else could it be? The FC reading today was 24, so I added 3 gal liquid CL to raise it to about 35.
Am I on the right track? Also, are the stains on the pool walls gonna require draining and acid wash to remove?

 

[duraleigh]

OK, rechecked CYA with alternative test

The Taylor CYA test is the most accurate on the market......what alternative did you use?

 

[Noorm]

The Taylor booklet suggested diluting sample with tap water, then doubling the multiplier.

 

[tim5055]

That is the correct method for checking high CYA. 30ppm FC is still too low for 120 CYA.

Using THIS CHART because your CYA is above 100 you find your shock level is a whopping 47 (46.7, but who is quibbling over a little)

The pool service probably used pucks and "shocked" the pool once a week with a powerded shock, thus your current CYA level.

I assume you have read the directions on SLAMing your pool in the How To section of Pool School.

The problem with high CYA is the insane amount of chlorine you need to kill algae once it gets a foothold. You may need to do something about the CYA first.

 

[Noorm]

That is the correct method for checking high CYA. 30ppm FC is still too low for 120 CYA.

Using THIS CHART because your CYA is above 100 you find your shock level is a whopping 47 (46.7, but who is quibbling over a little)

The pool service probably used pucks and "shocked" the pool once a week with a powerded shock, thus your current CYA level.

I assume you have read the directions on SLAMing your pool in the How To section of Pool School.

The problem with high CYA is the insane amount of chlorine you need to kill algae once it gets a foothold. You may need to do something about the CYA first.

Okay, I see where I failed to read the test correctly. Got the dilution part, but forgot to double the reading, so apparently I am actually at 120 ppm. So now my only solution is to start replacing water, right? Any figures on how much water needs to be replaced to cut the CYA in half? With the drought we are experiencing, that may be a problem. (Dang, I've used up most of the CYA reagent in the test kit.)
Actually my pool is crystal clear, and the stuff is not forming nearly as much on the sides, but it is still there. Also, I'm still wondering if the staining will ever go away. No matter how hard and long I go at it with the wire brush, the underlying splotchy stains remain.

 

[kimkats]

Replace some of your water. use this link to see how much. http://www.troublefreepool.com/calc.html

Once you have your cys down to 50 or so you will have a much easier time killing what is causing the yellow.

Kim

 

[Patrick_B]

Cya reduction is linear to water replacement. 50% drain and refill would give you the same reduction. The Taylor 2006 is a wonderful kit, but this reagent shortcoming is why we suggest the TF100 kit like we do. Same reagents but in higher quantity.

 

[Noorm]

Cya reduction is linear to water replacement. 50% drain and refill would give you the same reduction. The Taylor 2006 is a wonderful kit, but this reagent shortcoming is why we suggest the TF100 kit like we do. Same reagents but in higher quantity.

Thanks. I now must decide whether to go against my water company's restrictions on drain and fill.

 

[tim5055]

Before you go out and get the water police all riled up, check out the ongoing threads on the new bio-active cya reducer on the market. Several folks an the board are testing it so we don't have an opinion yet, but it may be something to look at. The current folks were starting at CYA levels in the 4 - 600 range. It seem sslow going for them, but you may be a good candidate for a more "normal" high CYA test.

Just and idea/option.

 

[Noorm]

Before you go out and get the water police all riled up, check out the ongoing threads on the new bio-active cya reducer on the market. Several folks an the board are testing it so we don't have an opinion yet, but it may be something to look at. The current folks were starting at CYA levels in the 4 - 600 range. It seem sslow going for them, but you may be a good candidate for a more "normal" high CYA test.

Just and idea/option.

Thanks, looks promising. My concern is that I have to lower FC before using the BioACtive product, and how long will it have to remain reduced, during which the algae will proliferate.