From: howardr@col.hp.com (Howard Rebel)
Subject: Re: Cannister Filter Question ?????????????????
Summary: I am a filtration nut...forgive me. (long)
Date: Wed, 2 Sep 1992 20:21:43 GMT
Organization: HP Colorado Springs Division

This is a lot longer then I intended it to be.  I was fishing a bit when
I wrote the following.  I was looking for feedback on my views and
RON was nice enough to provide it.

In article <1992Sep2.134048.10174@minnow.sp.unisys.com> ron@minnow.UUCP (Ron Burns) writes:
>In article <1992Sep1.161402.10690@col.hp.com> howardr@col.hp.com (Howard Rebel) writes:
>.....
>>
>>If the chem filter comes prior to or after a non existent or undersized
>>bio filter then then chem filter will take on the function of a bio filter.
>>The bacteria present in bio filters will coat the chem filter particles
>>and render them useless as a chem filter.
>.......
>>Howard Rebel hpcsos.col.hp.com 
>>
>
>Yes and no.  While this may be a fine way to set up the filter, I don't
>think we want to lead anyone to believe that this is exactly true.

	But is it not true?  Once the chemical media gets coated with
	bacteria slime it will no longer be able to contact the water
	directly and thus no longer function as a chemical filter.
	I suspect that the truth is that most of the carbon used in
	the hobby quits working due to a slime coat. 

>If it were true that bacteria only live in the part of the system WE call
>the bio filter, ok.  But there are no little bacteria fences, or signs 
>saying 'Stop! Go back to your homes!' as the water passes out of the
>bio media.  There are bacteria on your carbon.  On the tank glass.  On your
>riser tubes and every where else.  

	I agree that the bacteria is most everywhere.  But in a CLEAN
	CYCLED tank the amount of ammonia present in the water entering
	the filter is so low that most of it should be converted to
	nitrate by the bio filter prior to the chemical filter.  If
	the chem filter sees little ammonia or nitrates there will be
	little or no bacterial growth in it.  At least less then if
	you used the chemical filter for a biological filter.

>This is true no matter if your filter is oversized or undersized.  Your
>only chances to keep the carbon free of nitrifying bacteria are:
>	1)  Create some kind of ONE PASS bio filter that ENSURES that
>		ALL ammonia, nitrite and nitrate are removed from ALL water
>		that leaves the filter.  Then allow the water to pass to the 
>		carbon.

	I like the term ONE PASS (may I borrow it)

	Would not an oversized biofilter do just that.  Just how large
	that would be I do not know.  But in a clean cycled tank...
	it may not be too large to tolerate.  I do not have the 
	equipment to measure the difference between the input and
	output of my filters so I have no way of determining how
	much filter it would take to do this.

>...
>None of these are feasible.  None are required.  It comes down to this.
>
>		Don't worry about bacteria on your carbon.

	You could be right but I am not buying the line unless I have
	some proof that the bacteria covered carbon is still functional.

	You are correct in that "non are required" but the less slime
	we have on the chem media the better it will work.  As you
	said it is a fine way to set up a filter.



	
-- 
Howard Rebel hpcsos.col.hp.com 

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