acqua normale in quello di sinistra e acqua torbida ma pulita nell'acquario appena allestito che vedete a destra Having the murky water in the aquarium can happen, and often is not anything serious.
Unfortunately the word "murky" is generic, then every time you have to understand what kind of "discoloration" we're talking about (not counting the people who write in email or in comments without specifying whether they have a saltwater aquarium and freshwater tropical ... or tempered, as if they were all the same!)
Basically, I happened to watch 3 main types of murky water in my experience with tropical aquariums:

  1. Dirty water / powder, typical of the early days of starting a new aquarium. E 'the situation more harmless, the powder is normally contained in the gravel which, if not rinsed, placed on the bottom it releases a great deal of which remains in suspension for days. What is coagulated on the surface can be easily removed by placing the water pieces of paper towel, then wiping it in a mechanical way. In the photo above you see an examples found on the Net that offers side by side just 2 tanks with clean water in both solo and one on the right is cloudy because just set, then the water is clearer because of suspended particles and bubbles of oxygen.
  2. greenish water, then a algal bloom. We are in particular conditions, in which an alga has found the conditions particularly suitable for proliferation in the water column. Usually a partial change of substantial and above 3-4 days of total cattle solve the problem.
  3. amber-yellow water, the result of the presence of dyes, often acid, produced by the roots, ie the so-called "bog woods" that may be more or less clean before being sold aquarist. This "rule" says to buy the logs of wood for aquarium, large or small, and, before putting them in their place on the bottom, boil for several minutes in a pot or, if too large, at least keep them to soak in the tub in hot water, tenendoceli for a few days.
    If the water is clear then that means that even in the aquarium will not release aidificanti / dyes
  4. water foggy (sometimes associated with bad odor), the result of a bacterial bloom, then the biological filter is not doing its job or that the doses of food are really exaggerated!
    More difficult to control and more dangerous than the 2 above, this situation should be tackled trying to understand its causes. Often comes from very far dall'optimum chemical conditions, such high values ​​of ammonia or nitrites. Check with testing all the values ​​and try to return them in accordance with changes of water, remove the fish before they die or become ill. Wait a few days later because the filter restarts with its beautiful nitrogen cycle (say 2-3 weeks) and then put the fish in the aquarium GRADUALLY.
    If the tub was active for some time ... whether the number of inhabitants is not too high for the liters available. Wanting to do just a penny count, try putting a plant every 2-5 fish (depending on size) and 1-3 fish per 10 liters. If we put too many fish the filter will not sustain the organic load, then even if we put a few plants then it is more difficult.