Is anyone else using the lamotte phosphate kit with the octet comparator. I seem to be having a little trouble making out the colors, especially in the high range. Has anyone come up witha tip for making it a little easier to decipher the colors? So far the only thing thats come close is natural sunlight thru a window but even then I can't really tell the difference between 1.5 and 2.0. I can see the difference on the comparator itself, the problem lies in getting the sample to match up colorwise.

Marcel

I know about this too Marcel and this is what I have to do. I take the kit after the processing time to my workshop which has a 2-tube fluorescent light right over the bench. I place the kit right under the light so it is shinning right down through the tubes. I also place a white 6” block of foam (just use anything pure white) right behind the kit so when I look through the comparator you are viewing everything against bright white.

Hope this helps.

You are taking the mixing caps off right?

Thanks av8tor, I'll try the white background next time I test. I always shine the light down thru the top so that it shines down thru the 3 test tubes. I'll be testing tomorrow so I'll let you know how it worked out. Yeah I take the mixing cap off.


Marcel

i use the same kit. at the begining it is a little tricky.make sure your test tubes are clean after you fill with water to be tested,so you don't have distortion. when finished clean test tubes good for next time. make sure your regents are not out of date,( been there!.) call lomotte if your not sure.
cleanlyness is next to godlyness! good luck!

cornhusker

I tested today, I'm still not overjoyed with the results. Am I trying to match the darkness of the color or the difference in color, ie: 1.5 and 2.0 are more violet than blue? I should ignore the edges of the sample color also as they fade into clear, right?


Maybe I'm trying to split hairs... I don't know.

Why do you need such accuracy at this range?
That's a question you might want to ask.

Assuming you do......
Try making some known standard solutions.
Say 1.2, 1.4, 1.6, 1.8, 2.0, 2.2 etc over the range of interest.
Then use these to gauge the test kit.

I use a colorimeter for more accurate test.
Color is tougher with your eye.

Regards,
Tom Barr

tom,
please explain your color meter to us. must be something used in a lab. it sounds to me that you have much more suffisticated equipment at your disposal.
thanks,cornhusker

Yes, I do, but you can still do a lot with the other test kits.

It uses a spec to measure light intensity and spectrum precisely, so it measures color in nanometers. You calibrate it and then start testing the samples. Then the data feeds into a an Excel file etc.
Takes a while to fire up but not if you need to do 5 to 1000 water samples.

They make very nice small ones, ion specific(singlke wavelength) for about 175$ea for NO3 that are accurate to 0.1ppm of NO3.
Reagents run about 45$.

Then you jump up to multiphotometers(these have preset wavelenghts of several sizes) and these run 500-1000$ new, and then spect's which cover any range of light from 400-700 or higher /lower ranges for 1200-5000$ or more depending on what they have.
There are also autoanalyzers that run even more, 10,000-50,000$ each.

I doubt many of the folks realize what I use and the level I've done some of these test.

It's not so much that, as it is ther assumptions you build in to the idea you want to test that's important, some times you need stuff like this for a number of things, we generally don't for hobbyists.

Even less so if you do EI, you don't need to test for non CO2 methods either, but it's nice to see what occurs there.

But it's not needed.

The non CO2 method can be improved on with some minimal dosing once every 1-3 weeks and I will discuss this later.


Regards,
Tom Barr

tom, thanks for input. i think we novices need to learn how to watch our plants and everything else will come with time . just like you've been preeching to us,(if somethings wrong,change water and start over.) most of us will agree that the BARR METHOD is working. i am real pleased with results.thanks,cornhusker

If ins something does not work right, talk and we will work through it and find the problem.

That's the way this works.
You keep going till you rule everything out.

Regards,
Tom Barr