If the plants are not absorbing the fertilizers fast enough, you may get ammonia and/or nitrite spike as the fertilizers will not be removed fast enough. For plants to absorb the fertilizers well and fast enough, you need good lighting (and some plants will need CO2). This is especially with respect to ferts in the form of tabs. Now, another thing is that if you overdose with ferts (or if plants don't absorb the ferts fast enough), you may have a big algae problem, as "leftover" ferts are food for algae.
Most of the fertilizers I've seen don't even have any ammonia/nitrite in them, though some do have ammoniun compounds (not the same). Changes in water chemistry will be very minor as long as you follow the dosing instructions.