Hi,
Can't see why you need to be worried at all. Part of the ingenious programming of The Matrix is a little subroutine that tells people to worry, so they worry for no good reason at all. For example The Matrix tells people to worry about pH fluctuations, so people scurry around spending their whole lives measuring and trying to stabilize pH. The wise entrepreneur invests in the companies that manufacture pH test kits, or in those that manufacture pH controllers. The people who aren't worried about pH (or KH or GH) don't have problems due to fluctuating pH.
It is a fact that the same elemental components that are responsible for GH also happen to be micronutrients. But there are only two of these; Calcium and Magnesium. Fundamentally therefore, it would be wiser to worry whether or not you have enough Ca and Mg than to worry about GH. If you're using RO or live in a soft water municipal area then simply adding a few teaspoons of Calcium salts and Magnesium salts at water change time solves that problem immediately. Measuring GH actually doesn't tell you anything because GH does not tell you how much Ca or Mg you actually have. GH only tells you what the
sum of the two are. Even if you live in a hard water area, you can still add these to see if it makes a difference. Once you confirm whether adding these salts makes a difference or not, you then no longer need to measure GH.
In the case of these parameters, worrying causes lots more problems than not worrying. If you want to worry then worry about CO2/flow and distribution. That's whats so sad about the whole test kit soap opera. Worrying about test kit readings diverts your attention away from where you really ought to be worried. Ironically, no test kit can tell you much about nutrient/CO2/flow and distribution. You have to look at the plants. I don't see why you need to be seasoned. Can you tell when you have algae? Of course you can. Do you have a lawn? Well, go outside and look at it. Can you tell if the grass is a nice deep dark green, or if it is pale or has a yellow tinge? If so then it's a very similar indication inside the tank. Nutrient test kits never could tell you any of this and that's why everyone continues to have problems, because they think that a test kit can tell you something better than what you own eyes can tell you.
Since test kits are all basically made the same way, using the same chemistry, how could you possibly hope to determine what brand is more accurate or more consistent? The BRANDS aren't even real. There probably aren't even that many test kit manufacturers in the world. The reagents are probably made in a few places and simply branded or bottled differently depending on the contract. I mean, most pH test kits are Bromothymol Blue. Do people actually think that Company A, or Company B, or even Brand X actually produce their own Bromo Blue in their own labs from scratch? I'm pretty sure they just go to the lowest bidding Bromo supplier, buy the reagent in bulk, chuck it in a bottle and put their label on it. It wouldn't surprise me if they all used the same suppliers. So you could easily have several competing brands whose products are identical inside the bottles. Isn't that just business as usual?
So at the end of the day, understanding the fundamentals of plant growth and using your eyeballs is much more important, and is much more useful than the information that any hobby grade test kit can give you. But this is not something to be depressed or worried about. It's actually the good news, because your eyeballs were given to you for free.
Cheers,