couple questions from a newbie about CYA, chlorine, leaf stain

[Mdragger88]

That is dichlor- its not even 99% because its filled with “blue” stuff -aka- copper & “other” mystery ingredients.
You don’t want copper in your water.
You don’t want mystery ingredients.
You don’t need cya.
It adds 1ppm of cya for each ppm of fc.
I wouldn’t use that.
It is not stronger or cheaper than bleach when you compare gallon to pound it also has other affects on cya & ph

Keep in mind that poolmath assumes 99% dichlor not 60% or whatever that is so you may not even get that much fc increase.

 

[generessler]

All the drop tests depend on (duh... ) accuracy of drops. I've found technique does make a difference. You want them as big and fat as possible every time. Hold the bottle exactly upright and let the drop grow gradually over a second or two until it finally falls. If you have a shaky hand like mine, try using two and/or resting elbows on the table. Of course sample size matters, too. And for a 5ml sample the chance of error is greater than 10 or 25.

 

[PoolStored]

QUESTION 1 -
is this normal for the error on 5ml to be this much? between 20 and 23 is a 15% error? im being careful, using dropper vertically.

Yes, error on all the drop tests are 1 drop, when vial is clean, vertical bottle and you are squeezing SLOOOWLY and letting drops drop under their own weight. That means 21, 22 and 23 are within margin of the test at 5ml. At 10ml, error is +/-.5 FC. At 25ml the error is +/- .2. The rest of your error is testing error...

If you want to get accurate, get one of these!

Smart Stir Magnetic Stirring Device

tftestkits.net

QUESTION 2 -
i see i have extra POOL TIME SHOCK MAX BLUE in a cabinet and was wondering what this is. it looks like the strenght is 72%, which is alot stronger than liquid chlorine. is this just a way to get chlorine levels way up? and does it increase CYA?

this is the product.

Avoid adding anything to your pool with Blue, Blu, Bloo or anything that sounds like BLUE, and avoid anything that is 3in1, 4in1, 6in1 or any Xin1.

 

[PoolStored]

And for a 5ml sample the chance of error is greater than 10 or 25.

Taylor tests are accurate to +/- 1 drop. With 5ml sample, error is +/- 1 drop. At 5FC the test error would be +/-20%. At 10 FC the test error would be 10%. At 20FC error would be 5%.

 

[generessler]

Taylor tests are accurate to +/- 1 drop. With 5ml sample, error is +/- 1 drop. At 5FC the test error would be +/-20%. At 10 FC the test error would be 10%. At 20FC error would be 5%.

All good and true. When I said "5ml sample the chance of error is greater than 10 or 25," I was actually thinking about getting the meniscus to hit the respective line of the vial. 1mm off for a 5ml sample causes 5 times as much error as for a 25ml sample, same as you're saying for drop size. I think it's roughly 2mm per ml, so that 1mm error is 10% of a 5ml sample. Combining +-1 drop error and sample measurement error can make for pretty big variance.

 

[eugchen]

ok makes sense on the error.

i wont use that shock stuff. thanks