Path: utzoo!hoptoad!uunet!littlei!percival!bucket!patti
From: patti@bucket.UUCP (Patti Beadles)
Newsgroups: alt.aquaria
Subject: Re: question about biological filtration
Message-ID: <658@bucket.UUCP>
Date: 3 Jan 88 19:05:39 GMT
References: <193@bacchus.DEC.COM>
Reply-To: patti@bucket.UUCP (Patti Beadles)
Organization: Rick's Home Grown Unix; Portland, OR
Lines: 29

In article <193@bacchus.DEC.COM> reid@decwrl.UUCP (Brian Reid) writes:
>
>I am puzzled why it is not possible to set up outboard gravel filters. 

It is.  The idea is that you have to filter the water through whatever it
is you're using.  This material develops a colony of nitrifying bacteria on
the exposed surfaces, and helps keep the nasty stuff out of your aquarium.
If you've been following the "Dutch Minireef" information in FAMA, you can
see that one of the main principles is an external biological filter with
large surface area.

>Perhaps the answer is that there are other substances that are more efficient
>than gravel when used outboard, such as polyester floss. Perhaps these
>"Bio-balls" things, that I read about but don't quite comprehend, are a
>gravel substitute for forming bacteria colonies on outboard filters.

Bio-balls are small (1" diameter) balls that have "prongs" all over them.
Thus, they have a very large surface area for their volume.  By putting them
in an external trickle filter (where water drips over them instead of having
them completely submerged) you get a high capacity for organic waste breakdown,
and a high dissolved oxygen content.  Youu can also use them in an external
canister filter.
>Brian Reid

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