Originally Posted by MakoMaui
That's correct. I'll be using my local tap water for water changes. I figure it'll be the cheapest way since I won't have to buy de-ionized or distilled water. Since I am on that topic, can you buy store-bought water depending on hardness and alkalinity? What is the purpose of testing for nitrates in the tap water? For plants, I'm not sure. I want something for beginners because this would be my first planted aquarium. I just want something that will thrive in my tank and that the fish will benefit from.
A little clarification... or just me rambling. Sometimes I'm not sure which it is...
If you test the GH and KH from the tap and you are not planting live plants it won't change much so it doesn't matter when you test it BUT even if you have plants and the water softens a bit as a result, your fresh water going in will always be the same so that is what you need to know. This helps to determine what fish you can keep and what plants might do well in your tank. Often it only needs to be tested once. I like to monitor my tank levels as well though.
If you are going to use plants and can get the ones that you want to start with and have the right bulbs as already suggested then I would suggest planting them all right away. This can avoid the whole tank nitrification cycling with it's associated spikes and allow you to add fish right away. Even so, don't add them all at once. The smaller the fish the more you could add though as it has to do with making sure that the plants can handle the ammonia that they produce. Two or three weeks between additions seems to work well.
On the nitrates:
The nitrification cycle takes ammonia and, through ammonia oxidizing organisms, produces nitrite which is then handled by another set of organisms to turn it into nitrate. We don't typically have anything to turn nitrate into harmless nitrogen gas in the aquarium so we need to rely on water changes to remove this build up. Some plants, particularly some floating plants like duckweed, amazon frogbit and similar, water hyacinth is actually used as a third stage water treatment in some countries, do use nitrates but often not enough to eliminate them. I have only ever seen 5ppm in my tank even after a 3 week hiatus from water changes due to a trip. Some substrate plants do this as well but I'm not sure how efficient they are or which ones do. This is where a good variety of plants is good.
If there are nitrates in your source water then you are starting out at a disadvantage. Anything over 20ppm should be of concern and it is best to keep it below 10ppm in the aquarium. Starting with 10ppm means that you only have a 10ppm margin rather than a 20ppm margin.
With plants and/or a properly cycled and established tank a bit of ammonia in the source water is of little concern but you should be aware of it so it is best to check for it. In another thread there is mention of the spring sometimes bringing changes in the water for any number of reasons, whether on a well or city supply, so it is probably best to do some seasonal water testing of your tap.
The plants are important as they use the ammonia before it gets to the nitrogen cycle. Every bit of ammonia that the plants use means less to become nitrite and, in turn, less to become nitrate.
As far as plants and ammonia sinking go, fast growing stems and floating plants are good starters. I have some dwarf hygrophila (polysperma) that are like bad weeds. I can cut them in half one week and still need to trim them a week or two later and my tank is just over 20" tall. I added duckweed for lack of any other available floater but it does a great job. I remove about half to 3/4's every week or two and the surface does fill back up quickly. Fast growth = ammonia usage. Others have anything from anacharis to watersprite
Hope that was helpful on some level.