20g freshwater tank...
I have been running my first tank for about a week. Everything is fine, I have no problems, but I am wondering about my water chemistry. Right now I have three black mollies, one African dwarf frog, and another African ___ frog (not sure on the name). I have well water (very hard) and I am wondering how hard water affects my fish. It'd be awesome if you could simply provide me with some links giving information on how different factors (pH, hardness, nitrate and nitrite levels) affect fish. Also, I'd like some information on the different freshwater habitats and what those habitats require as far as chemistry goes. I'm trying to plan out a 55g tank and any information you could provide via reply or links regarding my questions would be greatly appreciated.
Well, the mollies like moderately hard water, which you've got. The frogs like it neutral to slightly alkaline. However, stability is the important thing. A stable pH and hardness is very important.
Nitrite is toxic to fishes and the presence of any amount of it indicates the aquarium isn't cycled. Nitrate, in low levels, isn't a problem for the vast majority of aquarium fish species. In higher levels, Nitrate can stress the fish as the natural bacteria within the fish converts the Nitrate back to Nitrite, which is of course, toxic. It can also hinder the ability of the blood to absorb Oxygen.
The fish that have been farmed for decades are adapted to varied levels of pH and hardness of a tank, as long as it is within a range the fish can adapt to. Neon tetras, for example, don't last long in water in the upper 7s of pH and hard; that's out of their range. Even though they are farmed in the tens of millions, Neon Tetras are originally from very, very soft, quite acidic waters in their native climes, and even those masses of captive-bred fishes still do best in it.
Each example of habitat that contains fish are of a character that the fish within the habitat developed in levels of pH, temperature and hardness, and it's in those that the fish live best (longest, healthiest) in captivity.
It's similar to humans. You, in Nebraska, are accustomed to the levels of heat and humidity and temperature that state experiences during a year. I'd doubt you'd enjoy the heat and humidity of the Southeast US; today here the high temperature was 98 (it's 85 now at 2 a.m.) and humidity was 92 percent with the dew point in the high 70's. The heat index (temperature plus humidity) was over 106. Yes, you could survive here, but I doubt you'd like it very much.
It's the same with fishes. Those from the great rift lakes of Africa live best in the high pH (8.2 to 8.4) and high hardness of those lakes. They can adapt to lower levels of pH and hardness, but not by much. The fish from those lakes developed in the hard and alkaline for many tens of thousands of years so the span of pH and hardness they can be kept at is quite narrow.
The term is called latitude; a span of pH and hardness a fish can be kept at for its continued health. Outside that range can change or hinder the way a fish can control its osmotic pressure, leading to such problems as susceptibility to disease, shortened life spans and other health issues. Marine fish that developed on the coral reefs of the world have perhaps the narrowest latitude of all. Coral reefs are perhaps the most stable environment on Earth, thus the fish from it can live only in the levels of pH, hardness, salt and mineral content of the reef they came from.
If you search by threads by me on the forum, you'll see several primers on various families and genre of fish. Idea water parameters are listed for all species.
Well, I think the free ebook offered on the site is a good place to start.
You can learn all about ammonia, nitrite and nitrate in the ebook in the section on cycling. Real quick - ammonia and nitrite are toxic, nitrate not as much. As far as the pH and hardness are concerned, that all depends on what fish you are interested in. Fish have a much easier time adjusting to the pH and hardness than they do with ammonia and nitrite. There are ways to alter your tank water, but I don't think that's a good idea for someone who is new to the hobby. Easiest/best thing for you to do is keep your tank water as close to your source as possible - consistancy is for more important than perfection. The chances of something going wrong go way up the second you start playing with the water.
There are as many different habitats as there are bodies of water, so that question can only be aswered by letting us know what kind of fish you wish to keep.
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