Water problems are the most diagnosable thing in the hobby and the most commonly guessed at. The difference is numbers. "My water is cloudy" has a dozen causes; the same post with readings and a tank age usually has one. Include: Ammonia, nitrite and nitrate , as numbers rather than "fine" or "safe". Say which test you used — strips and liquid kits disagree, and the disagreement matters. How old the tank is , and whether it has ever finished cycling. What you changed recently — a water change, a filter clean, a new fish, a new food. Most sudden problems follow a change by a day or two. For algae: how many hours the light is on, whether daylight reaches the tank, and how often you feed. If a fish is gasping at the surface right now, do not wait for a reply — test ammonia and nitrite, and do a water change if either is above zero. Then post. One house rule, and it is the only one that matters: answer the question that was asked, and say when you are not sure. A confident wrong answer costs somebody a fish.