An API freshwater master test kit will run you @30-35 dollars at a big chain pet store. Its about $10 cheaper online (amazon). The kit includes tests for ammonia, nitrite, nitrate, ph, & high-range ph. There are literally hundreds of tests you can perform so both the accuracy & the cost per test (pennies) make it a worthwhile investment! The amount of ammonia you have to add is dependant on various factors such as is there ammonia in your tap/source water or what type & strength of ammonia (% ammonium hydroxide)? For example-you wont have to add as much ammonia if theres ammonia in your tap or the weaker the ammonia is (%), the more you have to add to get to 4ppm.