I second getting Salifert: it's expensive to rig out with new test kits, but so is livestock, which you can lose if you correct in a wrong direction because your test screwed up.
Salifert tests don't depend on subjective color judgements: the color changes happen suddenly and profoundly. You stop dropping stuff in the vial at that point and just look at the plain number on your dropper/syringe, nothing subjective about it. It's just a number, which you can write down in a book and compare against an acceptable range, and decide for yourself whether 8 is enough or you'd rather be, say, at 9, in an acceptable range of 8-11. You can decide which of two readings to 'correct' for the day, when you can't correct, say, low calcium and low alkalinity at the same time. If your alk is 8 and your cal is 340 (s/b 400), you can say: "I'd better fix the calcium today, and drop in some buffer (alk) tomorrow," rather than being told "It's an 'acceptable' level...' With that, you're shooting in the dark, rather than making informed judgements. Just my personal preference, but it would be my best advice. You can, IMHO, have a better chance to steer this tank through its problems if you have more precise information about what's going on with the chemistry, and a more exact knowledge of what you can correct, and when---eg, knowing that you don't correct alk and cal at the same time (the result would be a small snowstorm in the tank, doing neither reading any good: best rule is correct one thing in any 24 hour period.) Hope that helps.