There are a few comments I can make on issues mentioned in post #6 as I consider them important to get straight.
I have seen products at the fish store pertaining to adding or taking away something to fix pH. Which I never really want to get that far into.
Never use pH adjusting products with fish in the tank. Actually, never use them period. The GH/KH/pH subject is pure chemistry and understanding the basic principle is mandatory. GH is the general or total hardness of water; this refers to the level of dissolved mineral (primarily calcium and magnesium, either or both). This is the soft/hard water bit. Soft water has a very low GH, while the GH increases the harder the water is. KH is carbonate hardness also called Alkalinity. For our purposes, it acts as a buffer to prevent the pH from fluctuating. The pH is more difficult to comprehend so I will leave out the chemistry; but it is tied to the GH and KH. CO2 (carbon dioxide) also impacts pH. And calcareous substances in the tank can impact pH as well as GH and KH; items like rock or substrate that is composed of limestone, marble, aragonite, coral, shells, etc. You cannot adjust the pH without dealing with the GH and KH. This is why the pH adjusting substances generally do not work long-term, along with other issues we can leave for the present.
A pH above 7.0 is basic (long ago it was termed alkaline, but that is misleading); below 7.0 it is acidic. Generally, softer water will be on the acidic side, while moderateely hard and harder water will be on the basic side. Fish from these different waters usually have such needs for pH.
You should be able to ascertain the GH, KH and pH of your tap water not from your landlord but from the municipal water authority. Check their website. Or call them. You want the number and their unit of measure for GH and KH as there are several. The pH will be whatever number it is. This is the starting point. Depending upon these numbers, we can predict what will (or won't) happen in the aquarium concerning pH.
Water treatments...which brand/type?
This is more important than many realize. Substances added to the tank water will get inside the fish. Fish continually take in water via osmosis through every cell. Substances in the water thus get into the fish's bloodstream, and into the internal organs. As a general principle, never add any substance to tank water unless it is absolutely necessary. The fish must deal with all these substances. It must maintain a blood pH that is the same as the water it lives in; it must filter out substances in the water via the kidneys primarily. But it gets much more involved.
This is where conditioners come in; only use a conditioner that does what you need and nothing more. "More" means more chemicals and more fiddling with the chemistry, and this only increases the risk to the fish. If you have chlorine and/or chloramine added to your tap water by the city, you obviously need a conditioner that detoxifies these; most do both. Heavy metals is usually included, and can't hurt. But nothing beyond this is needed unless you have ammonia, nitrite or nitrate in the tap water.
