I think for most aquarist, simply looking at the practical side of things and the trade offs and reducing the unknowns is perhaps a more pragmatic argument.
Water changes: => easy, no chemistry required, clean the tank out, water clear, and clean.
Dosing errors=> totally minimized via large weekly water changes.
Cost: test kits and actually using them does cost something and the reagents are not exactly enviornmentally friendly either......
Water changes cost $ as well, however, the waste can be used to recharge ground water, water landscaping etc.
Simple, no testing, no chem knowledge required.
This is not to say that the test kits are bad per se, or that it's not to recommended ever etc.
But for most folks, they really do not need them and really are less practical than most seem to believe in the hobby.
Test kits introduce their own set of errors that need accounted for and when you add that to the aquarium honbby anbd mix, now you do need more understanding and chemistry.
Problem is, most aquarist do not wnat to use the test kits correctly and use reference standards.
They think they can get by with short cuts and argue that their test show the evidence, even though the readings may or may not be off by kilometers..........
Now if you are going to accept some trade offs and not bother to calibrate, and therefore guess the test kit is correct, would you not be better off not even going down this test kit path to begin with?
You are estimating with EI, based on a known volume of water change.
With test kits, without calibrating, you are guessing outright and assumign they are correct.
Guessing vs estimating.
Which is worse?
Ironically the test kit lovers all suggest their's is a better more accurate method.
Yet few seem to be able to calibrate the test kit and want to take short cuts.
I use test kits to measure the models I make for predictions vs what is actually in the tank itself.
So I need and demand accuracy when I test.
I also do not need to test all the time if my model predictions are well matched with my test results.
Therefore I do not waste my time playing with test kits since I have a good model predictor.
But some clowns just do not get it.
They think you must test and do so forever.
I use testing for experimentation/manipulation/purpose driven questions, so I can make predictions and then apply them to aquariums/lakes, ponds etc.
Then I do not need to test forever 😉
I can automate a water change or make it very easy/simple to do also(Hard plumb a valve for drain and for filling).
I cannot automate NO3, PO4 testing nor KH.
The other thing that the test kit crowd are just plain terrible at: measuring CO2.
For all the talk and banter over test kits and N etc, they are terrible when it comes to measuring the 2 big parameters in the hobby: light and CO2.
Irony has no limit.
Why spend all this effort on NO3, PO4 etc when you do not address the 2 main components to plant growth?
I've never met a single pro test kit person that uses a light meter using PAR in this hobby to date.
Ever............
CO2?
Some readings might be right, but many are not.
If you have measured CO2 very critically, then you know the plant responses, you know the algae responses, so even if the test say one thing, you know it cannot be correct, something must be off for the plant to be looking like that and it cannot be the CO2.
Many aquarist claim they have everything correct and do not check it twice.
I'm always amazed at how sure they are yet scratch their heads about why they still have stunted plant tips or algae.
Stunted tips and smaller growth at the apex is classic poor CO2. Blackening Java fern= classic poor CO2, BBA etc......increased Hair algae growth..............lower O2 levels during the day..........
I've gone back and corrected perhaps 100X these situations and cured the issue using nothing other than CO2 changes.
I have a 2500$ CO2 meter that is independent of pH/KH and is accurate to 1ppm and a response time of about 5-10 min.
I am a bit more interested in experimental designs, research, testing than most. I also calibrate it and make sure it measures true against a known standard. Then I can really isolate and measure this one parameter and see what impact it has.
Folks do not like it when you question their long held beliefs, they do not like it when you question the test kits they claim make their point, they do not like to be wrong, yet cannot explain why things are okay when you have these high levels, and why others folks who measure with crappy test kits have issues as well.
There is a great deal of irony, conflict and contradiction in their logic.
Logic that will never win out over time.
Regards,
Tom Barr