Doing the FC test with the Taylor kit

[ddas]

I have the Taylor K-2006 kit.

For measuring FC, the instructions say to put "2 dippers" of the DPD powder in.

Sorry to be a stickler about this, but what does that mean? The dipper stick is flat, so I can go in and scoop it, but how big of a scoop? A flat scoop? A heap? As full a heap as fits on the dipper stick?

The only reason I ask is because I'm assuming I'd probably get vastly different chlorine measurements whether I scoop generously or scoop conservatively. I can easily justify "1 dipper" as being +/- 50% of another dipper, depending on your definition of dipper.

So how much DPD powder are you REALLY supposed to put in?

 

[JohnT]

Enough to make the water turn pink. Usually one scoop will do, but the exact amount isn't critical. One end of the dipper is a scoop, albeit a very small one.

 

[jblizzle]

You are supposed to hold the flat side and use the little cup on the other side.

You can not use too much powder, but too little can sometime be a problem. As long as the sample starts out with a nice pink color, you have used enough. One scoop is likely plenty, you may only need a 2nd scoop if you are SLAMing at high FC levels.

 

[ddas]

Thanks a lot -- that info helps.

I was worried that too much/little powder could skew the results by a magnitude of 2x or 3x, but it sounds like that's not really the case. I always put in enough to turn the water bright pink. So at worst, I might have been using a bit too much.

 

[bdex]

I put in 2 level scoops. As close to level as I can get.


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[hAltonJones]

In the chemistry labs, a "scoop" was always a "level" spoon or scoop. Off the top of my head, adding much more would skew the results, but I'm just a newbie myself. I'd be immensely curious to see if you get the same results running the test with two level scoops and then running it again with four level scoops. However, "immensely curious" doesn't include a willingness to use up some of my expensive reagents unnecessarily.

If someone does this, please post the results. Thanks.

 

[jblizzle]

Off the top of my head, adding much more would skew the results, but I'm just a newbie myself.

It does not skew the results.

 

[JVTrain]

My thoughts on this topic from a previous thread:

There are two types of testers with regards to DPD powder on TFP.

Type one - "Two Level Scoopers" - They pride themselves on super accuracy and consistent results. Their DPD powder is stored in a humidity controlled vessel to prevent clumping and discoloration. They level their scoops with a razor blade and have been known to calibrate their scoops using certified balances for weight checking. Scoops are ordered by the dozen from tftestkits.net in case they need a back up, but this also adds to the calibration workload.

Type two - "Heapers" - This groups prides themselves on being able to judge how much is "enough" based on the appearance of a scoopful alone. No leveling, no sifting, just a single heaper and it's off to the races, testing. Frequently, their scoops look like something out of a horror film torture chamber. Time and humidity have taken their toll on the scoop, now coated in a black and brown film of varying thickness. The scoop has certainly lost some capacity due to this coating, but the Heaper knows that just a little taller heap will even that out.

I'm firmly in the Heaper group...