Hi all,
The first point is that ammonia (NH3) is highly toxic, and I wouldn't recommend adding more of it than occurs naturally to any tank. The pro's and con's of fishless cycling come up quite often as a subject, and have generated a large amount of debate, much of it fairly acrimonious, and I no longer post on some threads because of this. This was, and is, my position on it: <
Cycling a planted tank | UK Aquatic Plant Society>
Without going over too much old ground, the other 2 major points are:
1. Test Kits tend to be unreliable in aquarium situations, mainly because there are lots of different ions present in the water that can interfere with the test result.
For some ions, like NO3-, this is particularly true and this affects ion selective electrodes as well.
Any dissolved gases are problematic because they are in equilibrium with the atmospheric conc. This means that we can't accurately test for NH3, DO or CO2, so we have to use a drop checker etc.
Some other parameters, such as pH, are more complex then they at first appear, which means that a pH value, even if accurate, needs some interpretation.
2. Filter cycling is much less relevant to the planted tank than an un-planted tank which relies of the microbial nitrification of NH3/NH4+ > NO2- > NO3-.
Plant/microbes systems are about an order of magnitude more efficient in ammonia removal, with plants also removing NO2- and NO3-.
There are a number of reasons for this increased efficiency, the primary ones being that the plants them selves remove fixed nitrogen and produce oxygen. Their secondary advantage is that they produce a much larger area for nitrification to occur in. Rather than relying on the filter media, you have the plant surfaces, and particularly the rhizosphere, the oxygenated zone around the roots within the substrate where nitrification reactions can occur.