What exactly is cycling??

I keep reading post about the tank cycling. I am new to this and not really sure what it means. I have a SW 29g biocube and my live sand has turned brown i have had the tank 3 weeks. Can anyone be of help and tell me what this means or what to do??
Thanks

 

You need some more flow. Cycling is what your tank has to do to be ready for fish. It has to go through a process of nitrites, amonia (I know that is misspelled sorry), and nitrates. As soon as your tank has spiked thoughs and are at 0 you have cycled your tank. As for the brown algea on the sand you need some more flow to help with that but it is part of the cycling your tank has to go through!

 

Cycling is just the buildup of the beneficial bacteria responsible for the breakdown of ammonia to nitrites, nitrites to nitrates and to some extent nitrates to nitrogen gas. When there is enough bacteria in your tank to handle this process in the presence of low bioload, it is considered cycled. This bacteria will build up on the rock, in the sand, on the glass, on every surface of the tank and equipement that is underwater.

Whenever you add a fish, the tank needs to catch up and while you will probably not notice a cycle happening, rest assured the bacteria levels are increasing to handle the additional bioload.

Now, you diatoms. This is normal. You have silicates present in the water that the diatoms are feeding on. Once this is gone, they will die off. The brown are the skeletons of the dead diatoms. They will be taken care of by the cleanup crew when it is time. Things will be a little ugly right now, but just be aware that this is normal and will pass. Your tank will clean up in due time. Just remember....go extremely slow and you will save time, money and livestock.

 

Hi Pinkypictures
Cycling is a term used to describe the process an aquarium goes through in order to be considered safe to add more stock - in simple terms - all creatures create waste and those wastes need to be broken down to Amonia - then Nitrite - then Nitrate - Bacteria that colonise the filter medium, the live rock, the substrate etc - do this job - but obviously on a new set up tank there is very few if any present - thus if you add a Damsel or 2 - their waste build up whilst the bacteria levels increase in order to cope with this - eventually the bacteria present can keep up with the waste produced and the Amonia level falls to 0 - followed by Nitrites - which again will drop to 0 - (Nitrates are another matter and there are far better people on this site than me who can advise you on how to acheive zero nitrates - but type of filter, density of live stock, frequency and type of feeding will all affect the nitrate levels

in addition to the amonia cycle described above - there are other impurities often found in new tank set ups - such as silicates ( commonly felt to arrive Via any plastics used such as internal or external filters - piping etc - silicates are used by Diatoms ( brown powdery substance that makes everything look untidy for a variable period - when these silicates are used up - the diatoms recede and go away ( may make a return if for example you add new plastics later like a new power head or additional pipework etc)

duration of diatoms depends on amount of silicates present and also water flow (As Canned mulder indicates these things thrive in quiter areas of the aquarium)

the bad news is that it looks bad to start with and then gets worse - dont panic - it runs its course and then fades away quicker than it arrived (IME)

basically

 

Thank you everyone for your help i was just worried that i should give up now that i had already done something wrong. I guess i will sit back and see what happens.

 

Cycling can be a lengthy process, and is really pretty cool
Live Rock and Live Sand will contain stuff that's not live, and is in fact dead. During the decay of this dead matter ammonia is released as a waste product of the bacteria breaking it down.
Other bacteria will find this ammonia beneficial and will consume it excreting nitrate which is also harmful.
Other bacteria will find the nitrate beneficial and consume it excreting nitrite which is less toxic.
Other bacteria (and algae and diatoms) will consume that.
(are you humming The Circle of Life yet? Really you should be. Reef tanks are significantly more complicated internally than fresh water tanks. There's really lots of neat stuff happening here!)
Diatoms come next, which is your brown stuff on the sand. It will be consumed by our dead stuff eating bacteria in short order.
Softer Algaes come next, not all are bad, some like Chaetomorpha is incredibly beneficial, some of it is not good at all for your tank. Reef tanks because of the already established biological complexity are far more adept at dealing with algae (Assuming your ammonia is under control and that your lighting is of good quality and in the correct spectrum.
Next up is the really good stuff. Coraline algae. It's a beneficial filter that grows in all different interesting colors on your live rock. It's an amazing source of color in a reef tank.
At this point your main cycle is over and it's time to test your water (Ammonia, Nitrate, and Nitrite values are correct, as well as Calcium and trace (Mg St) elemets, PH, and Alk)
Assuming these parameters are right, head over to reefcleaners, and have them spec an invert cleanup crew, and you're on your way.

Always test before considering adding fish, test frequently otherwise, and don't overstock your tank. Really 6-8" of ADULT fish length are what you're going to be able to fit in a tank. Many fish have special needs and it's always a good idea to talk to the LFS and a couple websites to see what fish are available and will fit in your tank. THEN (and this is important) come here and ask about them as tankmates. Have us confirm you aren't overstocking, and we'll probably quiz you on diet requirements to make sure that you're taking care of 'em right. No one likes dead fish. (the same goes for Coral and Anemones, but I wouldn't be considering either yet)

The only stupid question is one left unasked that results in dead fish! I'm always willing to answer questions no matter how many times they're asked. I'll never suggest you should have searched the forum, or blow off the question as "newbish".

I will rip you mercilessly if you did something stupid that resulted in dead livestock. Please don't be the guy who shows up later because he overstocked incompatible fish and I have to tell him his tank's crashed and that he killed fish because of his own negligence. Salt water fish are amazing, have awesome personalities, and deserve better.

 

A Typical Break-In Cycle