I'm getting FC #'s all over the map. The directions call for "two dippers" of the R-0870 DPD powder. This seems very non-repeatable to me. Sometimes the crystals clump together, sometimes a few stick to the dipper. Also there's no compensation for 10 ml vs 25 mL sample? How important is the amount of crystals to the test results? Or can I just add any amount that turns the sample pink?
how important are the "two dippers" for the chlorine test?
- Thread starter twd000
- Start date
Re: how important are the "two dippers" for the chlorine tes
If you have one or two undissolved crystals before you start adding drops, you have enough.
If you have one or two undissolved crystals before you start adding drops, you have enough.
Re: how important are the "two dippers" for the chlorine tes
my experience is I use a heaped spoonful of powder, and providing I get a good solid pink colour after swirling, the result is accurate.
my experience is I use a heaped spoonful of powder, and providing I get a good solid pink colour after swirling, the result is accurate.
Re: how important are the "two dippers" for the chlorine tes
I pretty much use one just over level spoon full and has been said, as long as I get a good pink........I'm good to go. I always have varying amounts of undissolved.
I pretty much use one just over level spoon full and has been said, as long as I get a good pink........I'm good to go. I always have varying amounts of undissolved.
Re: how important are the "two dippers" for the chlorine tes
The amount you really need varies with the FC level. The higher the FC level, the more powder you need to use. If the sample turns pink right when you add powder, and then goes clear or brown you aren't using enough powder.
It is always safer to use a little extra, rather than too little. Using too little will give you false low results. Using too much, within reason, won't affect the results.
The amount you really need varies with the FC level. The higher the FC level, the more powder you need to use. If the sample turns pink right when you add powder, and then goes clear or brown you aren't using enough powder.
It is always safer to use a little extra, rather than too little. Using too little will give you false low results. Using too much, within reason, won't affect the results.
Re: how important are the "two dippers" for the chlorine tes
ok, so the degree of pinkness is not critical to the accuracy of the test? just add enough till it turns pink and stays pink
ok, so the degree of pinkness is not critical to the accuracy of the test? just add enough till it turns pink and stays pink
Re: how important are the "two dippers" for the chlorine tes
Yes. As long as the water stays pink you are good.
Yes. As long as the water stays pink you are good.
Re: how important are the "two dippers" for the chlorine tes
Well, yes and no. If the solution goes pink and then clear you have obviously used too little powder. But if you could somehow add just enough to get it slightly pink again that wouldn't be enough. The odds are heavily against that happening however. If you add more, chances are it is more than enough or not nearly enough. Or to put that another way, the range over which it can be slightly pink is very narrow compared to the size of even that tiny spoon. The odds of hitting that narrow range are quite low.
The rule Stuamurr mentioned, add till you get a good solid pink is a good rule in all cases except one. If the FC level is quite low then nothing will ever turn it a good solid pink. But given your FC level is above perhaps 1 or 2, then the solid pink rule works well.
Well, yes and no. If the solution goes pink and then clear you have obviously used too little powder. But if you could somehow add just enough to get it slightly pink again that wouldn't be enough. The odds are heavily against that happening however. If you add more, chances are it is more than enough or not nearly enough. Or to put that another way, the range over which it can be slightly pink is very narrow compared to the size of even that tiny spoon. The odds of hitting that narrow range are quite low.
The rule Stuamurr mentioned, add till you get a good solid pink is a good rule in all cases except one. If the FC level is quite low then nothing will ever turn it a good solid pink. But given your FC level is above perhaps 1 or 2, then the solid pink rule works well.
Re: how important are the "two dippers" for the chlorine tes
here are today's test results:
temperature: 74 avg (needed my wetsuit in the deep end!)
pH: 7.6
CYA: ~50
FC: 2-4
CC: 0
TA: 150.36
CH: 200
So when I ran the free chlorine test on a 25 mL sample, I got 4 ppm. When I ran it on the same sample in 10 mL size, I got 2 ppm. Am I correct in assuming the larger sample test would be more accurate?
here are today's test results:
temperature: 74 avg (needed my wetsuit in the deep end!)
pH: 7.6
CYA: ~50
FC: 2-4
CC: 0
TA: 150.36
CH: 200
So when I ran the free chlorine test on a 25 mL sample, I got 4 ppm. When I ran it on the same sample in 10 mL size, I got 2 ppm. Am I correct in assuming the larger sample test would be more accurate?
Re: how important are the "two dippers" for the chlorine tes
How many drops did you use for each FC test? That is a large difference.
Was it really 20 drops with 25ml and only 4 drops with 10ml?
How many drops did you use for each FC test? That is a large difference.
Was it really 20 drops with 25ml and only 4 drops with 10ml?
Re: how important are the "two dippers" for the chlorine tes
sorry, reported it backwards
10 drops in the 25 mL sample = 2 ppm
8 drops in the 10 mL sample = 4 ppm
sorry, reported it backwards
10 drops in the 25 mL sample = 2 ppm
8 drops in the 10 mL sample = 4 ppm
Re: how important are the "two dippers" for the chlorine tes
At normal FC levels, the main issue with using too little powder, especially if you were to use a 25 ml sample size, is that the endpoint transition is weaker since the dye color before that last drop is less saturated in color since chlorine mostly but not completely oxidizes the dye (i.e. there is an equilibrium involved). For a 10 ml sample size, this usually isn't much of an issue and using a heaping single scoop usually works well for most people.
At normal FC levels, the main issue with using too little powder, especially if you were to use a 25 ml sample size, is that the endpoint transition is weaker since the dye color before that last drop is less saturated in color since chlorine mostly but not completely oxidizes the dye (i.e. there is an equilibrium involved). For a 10 ml sample size, this usually isn't much of an issue and using a heaping single scoop usually works well for most people.