Alternate testing formulas to use less reagents?

[JamieP]

It has been brought to my attention through my bicarbonate startup thread that some tests can be adjusted to use less reagents. Is there a place to find a summary of these, or perhaps by listing the alternate methods for each test here, it would help others too. I don't know if there are times when using the full sample amount vs the lesser sample size is more appropriate, so if this matters, please include that too.

Thanks!

 

[Texas Splash]

The Extended Test Kit Directions gives a few. Make sure you look down in the "notes".

Here's just one example (FC):
FC REAGENT VARIATIONS
5ml sample, multiply drop count by 1 (used to save on reagent; not as precise)
10ml sample, multiply drop count by .5 (standard method)
25ml sample, multiply drop count by .2 (used for extreme precision)

 

[JamieP]

The Extended Test Kit Directions gives a few. Make sure you look down in the "notes".

Here's just one example (FC):
FC REAGENT VARIATIONS
5ml sample, multiply drop count by 1 (used to save on reagent; not as precise)
10ml sample, multiply drop count by .5 (standard method)
25ml sample, multiply drop count by .2 (used for extreme precision)

Thanks! I thought maybe I was just missing something. I'll have to write all of these down.

 

[Schorschi]

With the CYA test in the TF-100 test kit it helps to save on reagent if you know your result to be 50 ppm or above and reduce your sample and reagent amounts accordingly (and proportionally).

For instance, 15 ml will fill the test tube just above the 50 ppm mark, so you need 7.5 ml of pool water and 7.5 ml of R-0013 reagent, which is about half of the amounts used compared to the test kit instructions. I use an oral syringe from Walmart (True Easy Syringe) and a bottle adapter to draw the right amount of reagent directly from the 8 oz. bottle of R-0013 that comes in the test kit, and another syringe (to avoid contamination) to draw pool water.

The True Easy Syringe has the added advantage that it uses "lockable" amount settings of 2.5, 5, 7.5 and 10 ml. So, once I dial-in the desired amount, I just draw the plunger until it stops at the preset setting and I only have to worry about getting rid of air bubbles. It's an extremely convenient, quick and accurate way of drawing the right amount of reagent or pool water.

The bottle adapter allows for sticking the syringe into the reagent bottle, inverting both bottle and syringe without spilling anything and drawing the reagent into the syringe.

So, if your CYA level is 50 ppm or above you can double the number of tests the TF-100 kit provides using the above method.

 

[Patrick_B]

Just for good measure Jamie, you always give up some accuracy when you dilute, or use smaller samples. One half dilution of the Cya test isn't so bad, but when you consider how infrequently you'll run it....well....it's not saving that much money in the long run. When things are normal again, it's best to go back to full sample sizes for the best numbers. On the FC TEST, it's with a lot of experince from my work that it's the worst test to skimp on. Unless the FC is extremely high, it's really not worth using the smallest sample size.

 

[JamieP]

Just for good measure Jamie, you always give up some accuracy when you dilute, or use smaller samples. One half dilution of the Cya test isn't so bad, but when you consider how infrequently you'll run it....well....it's not saving that much money in the long run. When things are normal again, it's best to go back to full sample sizes for the best numbers. On the FC TEST, it's with a lot of experince from my work that it's the worst test to skimp on. Unless the FC is extremely high, it's really not worth using the smallest sample size.

Thanks Patrick. This is good to know. This mostly came up because initially I was blowing through the TA reagents with the Bicarbonate startup because I didn't know you could use a 10 ml sample instead of the 25 ml sample, and we were testing every 2 hours! Brian got me straightened out on that though, and helped improve my accuracy!

 

[Patrick_B]

I've seen your thread here and there, but just enough to know how much help he's been to you. Good guy that Brian.

 

[JamieP]

I've seen your thread here and there, but just enough to know how much help he's been to you. Good guy that Brian.

I can't agree enough about Brian! He's the epitome of the kind of generous and selfless help TFP prides itself on. I am very grateful for his, and everyone else's guidance.