• Looking to buy a cephalopod? Check out Tomh's Cephs Forum, and this post in particular shares important info about our policies as it relates to responsible ceph-keeping.


Jan 23, 2008
hi all, i hate to be the dummy that doesnt know anything, but i was wondering if i could get some clarification. in my other threads i requested troubleshooting for my tank. what is a "flow through" system? a "closed-system"? and this whole "cycling" thing. we've only kept seahorses and random fish before this and never came across any of this. help please!:oops:
A flow through system is a system where water from a clean source, usually the ocean, flows through the tank. Essentially, the water is being constantly changed.
A closed system is a system where the water for the most part stays in the tank, and a portion of that water is changed however often the person keeping the tank determines it to be necessary.
Cycling generally refers to nitrifying bacteria establishing themselves in enough quantity to break down ammonia waste into something less toxic. Fish waste and rotting food break down into ammonia (toxic), aerobic bacteria convert ammonia to nitrite (toxic), then to nitrate (less toxic). This establishment is called the 'cycle', and takes time to stabilize, which is the reason for the notion of leaving the tank basically empty of livestock for 3 month. Nitrates can be exported though water changes or more commonly, the use of natural nitrate reduction (NNR) using anaerobic bacteria in sand beds or in live rock or a combination.

The above is a very general overview, and there are many ways to skin a saltwater tank. :smile:

If you want to keep saltwater animals long term (more than a week) I would urge you to get a hold of a decent saltwater book - The Reef Aquarium vol 1 by Sprung and Delbeek is great, but a little pricy, The Conscientious Marine Aquarist by Bob Fenner is good, and even "Saltwater for Dummies" suprisingly has great information. You could also do a lot of reading on line - http://www.reefs.org/library/newbieguide.html and http://www.reefs.org/phpBB2/viewtopic.php?t=33928 are good places to start, as are the articles in the article section of TONMO.


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