API Master Test Kit - Test Tubes

@suzie61
I 100% agree with your comments on the inadequacy of the colour charts. I went through that same "What the Hell?" phase when I started. It gets worse when you buy your second and third test kit and find different colour cards in each!
I found three solutions, one is quick and easy, the second is just an improved test method the final more involved but completely solves the problem.
The quick solution is to google images of the colour charts and find an accurate one - I know that a stupid statement but what I mean is find one that 'looks' correct, that does actually transition from yellow through to whatever the darkest colour is in progressive steps without repeats (I have even seen even inversions in the charts!)
Once you have a good one view it on a tablet and zoom in so its nice a large with part of the white background in the view. Then hold the tube with it backlit by this white area. I accept this may also not be a perfect reading method but it is very consistent and much easier to read as it removes the variability of lighting.

A couple of other things I then do to improve the test itself.
No 1 Always but always shake the solution bottles, especially bottle 2 of the Nitrate test. Shake and bang this one to death before starting the test and then again as the instruction say before adding it, this will ensure the solution is fully suspended. It will give a better immediate test result and more importantly, doesn't allow the solution to get progressively more concentrate over the months as it is used up. I have seem people complain about 50ppm differences between old and new kits but I have done the same and been within 3ppm NitrAte so this does work.

Mark the tubes so you always use the same tube for the same test, and wash them well and straight after testing, this reduces the contamination.

Those were the big ones, the next are optional.
The test tube volumes are not consistent - try pouring from one to another and you probably see a difference. I now use a 5ml syringe that I blagged from the practice nurse (careful how you ask, unless you want some drug counselling ) these are much more accurate and remove the need to read the meniscus.

I don't use the test tubes for mixing the test but have a supply of disposable centrifuge phials, the tops actually seal and again you can give them a good shake and discard them after a couple of dozen tests to again reduce the possibility of contamination.

The final fix is a big one and I absolutely accept its not for everyone, but it is the gold standard.
I found a low(ish) cost colourimeter, it was $100 but it has the colour spectrum for all the API tests built in.
It its just a techy way of reading the colours but its much more accurate than the eye and massively better than the stupid colour charts.
I think it is actually much more accurate than is required, I believe it can repeatedly test water samples to within a ppm. This is definitely not required for NitrAte, but for Ammonia and NitrIte this sort of accuracy is fantastic, and I still think its the best bit of kit I have ever bought. But there again, I'm weird
Regards
Andy