I've discovered several ways to be stingy and do less work when testing tanks (and multiple bowls) with API's master kit/dropper test kits.
The first is to get a childrens' medicine dropper/scoop kit for two bucks at Walgreens etc. This has milliliter markings on it.
To get water from the tank in volume with the dropper, squeeze the bulb flat and pull out more than you want then gently spray what you don't need back in or into your wastewater bucket. Never dump used vials into the wastewater.
The ammonia test.
Ammonia drops test is a two part test that involves chemically treating the ammonia in the vial with chemical A then checking how much A+Ammonia was created with chemical B. I've found that both after chem A and chem B the vial will spit a little out due to gas expansion from the reactions.
To spot check for ammonia you don't have to be very precise, on the opposite side of the milliliter markings on the dropper you'll see a 1/4 teaspoon measure. Put that much water in the ammonia test vial then proceed with the instructions using ONLY two drops of each chemical. The response you get will not be accurate but it will give a "precise negative" if no ammonia is present (good filtration)
To do a regular accuracy check you can use the bottom of the 1/2 teaspoon line and do the test with four drops each chemical.
The ammonia test can be thrown off by residual chemicals from the nitrate test, be sure to wrap a line of tape around the ammonia test tube and rinse it AND its cap thoroughly with body temp water when done with each individual test.
The Nitrite Test
The chemical used in testing nitrites is a one-shot chemical that can be used at one drop per mililiter, if you're uncomfortable using just one milliliter of water you can do it in how ever many milliliters/drops you like. Since we're looking to zero the nitrite as well, the one-drop test suffices. If you get a negative reading and you think there should be nitrite in the water one of three things could have happened; Nitrite test chemical CAN go bad with age and heat. Residual pH testing chemical of either sort can block the test and give false negatives. Nitrate ppm over about 320 can make the test sluggish. When you get a negative reading after the five minute wait, give the tube another few seconds of shaking. Thick heavy drop-to-bottom of the test chemical drops can indicate high nitrate as well.
The Nitrate Test
This is a 2 drop per milliliter test and as such you can do it with just one milliliter of water, however the nitrate test requires VIGOROUS shaking and is more accurate the more you use. I advise skimping no less than 3 milliliters and six drops. Remember this test will build up a small pressure in the tube and some chemical will come out both on first AND second shakes. API accounted for this and as long as you don't lose more than half a milliliter you'll still be within 10% of accurate results.
When I say VIGOROUS I mean you must shake the vial and #2 bottle like you're trying to get lunch money out of a bully. There is no "too hard" for shaking the #2 chemical before squeezing out drops during the test and I usually just go ahead and shake both the #1 chem in the test water and #2 chem in the bottle for the full minute it wants mixing. It's good exercise, just don't slam the test tube on your desk.
Nitrate tests can sometimes take longer to mature... in low temperature conditions I'd give the #1 chemical at least a minute of shaking in the vial and I'd not worry about how long the test says to wait before reading... after about six hours in shade at room temp the color will start to fade from the finished test but ten minutes check is as good as five at sixty degrees.
The pH tests:
I don't like API's master kit pH test card accuracy and if you don't want to mildly guess at your water's pH you can get what's called a "wide range" test from API. It's much more colorful and easier to read than either the High or Low range tests and is a 5 drop to 5 milliliter so you can do two milliliters just fine.
Low range pH test: Just do the 5 milliliters and three drops. This test is sensitive to the residuals of other chemicals but only by a small amount. It will still read within about 0.3 pH of accurate. Added aquarium salt and some antibiotics will affect the reading so don't react immediately if the pH is a bit off.
High range pH test is a drop per milliliter test but I would not use less than three milliliters and three drops for it. It can be difficult to read and slower to respond than the low range test.
Few bits to think about
: Eyes ears mouth and nose. All the chemicals in these test kits can cause irritation. The ammonia test kit is the most risky because it is not only designed to react to a chemical that exists in our skin but also because it creates two new chemicals from that reaction.
At just about any drug store you can find Vinyl gloves, just use them on the shaking hand then wipe them off between tests. I prefer "Clean Ones" Nitrile gloves you can find in Walmart back by the engine cleaners. Nitrile is what I wear at work while using pesticides, herbicides and fertilizers and it is a very chemical-proof glove, the "Clean Ones" are thin tho, so just dispose of them when done. Always dispose of a protective glove that has a hole in it.