hi everyone can you tell me how often a tank should cycle i have been told that your tank should cycle every hour do you guys agree i am setting up a 40 tank fish room and i would like water supply to be right cheers

The tank should only cycle once when you set it up. If you mean turnover, the how many times per hour the filter pumps the tank's volume through it, that depends. Most filter's "Suggested tank size" is based on 2-3 times per hour. You're better off with more than that. 5x per hour or more.

I may be wrong but I read once that once the tank/filter is fully cycled the filter converts ammonia (harmful) into nitrate (safe) in 24hrs, which of course becomes a continual process as the filter is always running. A heavily planted tank removes ammonia straight away.

The cycling is carried out by a whole range of microorganisms, each carrying out a stage in the conversion of nitrogen to nitrate and back to nitrogen in the plant decay process. It usually goes from urea from fish urine to removal as nitrate when the plants are removed after propagation. The plants can only remove nitrogen as nitrate and only when they are established and growing. All the other stages are toxic to fish and the bugs reproduce to handle the food available (in the form they prefer) and when that occurs we say the tank has cycled. A lot of the little critters that do this job for us live in the filter so the process works best when the filter is half clogged up with gunk (and helpful bugs)

Are you talking about cycling (which is something you do once per setup) or water turn over (which is a number of times per hour)??

hi i may of used wrong term volume of water turn over is what i meant cheers

lol internet flaw # 4021 detecting the intended use of a word which has multiple meanings. As Ira said, you want at least 5X tank volume/hour or more. At least it's not as bad as marine which needs at least 10X

You need a lot less turnover in a well established heavily planted tank.