Halve sample when doing SLAM

[simonoaks]

So, as with other tests, it seems you can change the sample size and adjust the relationship between drops and counts for expected high numbers - such as CH test.

Does this mean, during SLAM, you could use 5ml sample instead of 10 (get exact measure using medical syringe) and make each drop count worth 10ppm instead of 5ppm.

Seem logical as you do have the option to do 25ml and have 2ppm count.

So , any reason why this would not work, if measured correctly?

thx

 

[singingpond]

Yes, this works, but will reduce accuracy somewhat. I definitely have used this approach during the early part of a SLAM, to save reagents during the frequent early tests when you are keeping your FC levels up. Later, when you get close to the end and want to have more precise results for OCLT, definitely go to larger sample sizes.

 

[DaninFLA]

I used 5ml sample size for FC during the SLAM when I was getting low on reagent. instead of 0.5ppm per drop it was 1ppm. but the accuracy is not as good as noted above. its fine when you are measure high FC, but for regular testing and I would say less than 15ppm, I would do the regular 0.5ppm (10ml)

 

[duraleigh]

DaninFla has got it right.

1 ppm resolution is not good enough to finish your SLAM but you can use it at the start.

Personally, I would find that confusing so I would never suggest it......it just adds one more complication to a test procedure.

That said, if you are comfortable doing that and can keep up when you have to change over to .5 ppm resolution.

Honestly, I doubt you would save enough to make it worthwhile so it's more of a personal thing.

Besides, I still have one in college and need the refill business!!

 

[DaninFLA]

DaninFla has got it right.

1 ppm resolution is not good enough to finish your SLAM but you can use it at the start.

Personally, I would find that confusing so I would never suggest it......it just adds one more complication to a test procedure.

That said, if you are comfortable doing that and can keep up when you have to change over to .5 ppm resolution.

Honestly, I doubt you would save enough to make it worthwhile so it's more of a personal thing.

Besides, I still have one in college and need the refill business!!

sorry Dave, not trying to take food off the table

for me, sometimes I would forget my count when I was at 50 or so, so doing the 5ml made it easier. big numbers are confusing

and don't worry, I have been buying plenty of refills from you!

 

[duraleigh]

I had not really thought about that long drop count.......that's a good point.

 

[simonoaks]

Right, thanks. It is not about saving the reagent - I bought a 26oz bottle of it during my last SLAM, it is just reducing the time and amount of drops.

 

[singingpond]

Yes, it is simpler to think of one drop = one ppm. No further math required, which is nice if you happen to be testing for chlorine while half asleep (which can occur during a SLAM, unfortunately).