From: howardr@col.hp.com (Howard Rebel)
Newsgroups: rec.aquaria
Subject: Wet/Dry madness...
Date: 15 Dec 1992 20:53:17 GMT
Organization: HP Colorado Springs Division
NNTP-Posting-Host: hplsdum.col.hp.com

What follows is rambling related to filters.

    1. Canisters are a pain to service.

Of late there has a few postings on the net that exclaim the merits of
Wet/Dry (trickle) filters esp in comparsion to canister filters.  

While it is true that a trickle filter's mechanical section is easier to
clean then a canister it has nothing to do with the fact that the trickle
filter is a Wet/Dry filter.  Most any filter where the mechinical media is
not locked inside a hard to open/close/seal canister can cleaim the same.

    2. Trickle filters are not allways a benifit.

It is true that a trickle filter can add oxygen to the water as it
passes over bio media but, if the water contains enough oxygen is the trickle
effect useful.  Or put another way, if you test the oxygen level of the water on
the output side of you non trickle biofilter and find the oxygen level is at or
near saturation why change to a trickle filter?  

    3. In search of the perfect filter.

I have been searching for the perfect filter and have built a few home spun 
units.  I have developed the following criteria.

    A: The mechinical stage must be easy to clean.

    B: The remaining stages must not trap any solids which get by the
       the mechinical stage.  

I have been using sponges for my bio stage for some time.  It took a while for
me too see the light.  In spite of my best efforts these sponges need cleaning
(drop the pH) every 3-6 months.  I tend to forget to clean the sponges because 
they do not look dirty or offer any visiable evidence of their state.  I use
micron cartridges (paper filters) as the mechinical stage and I did not expect
the sponges to collect (or generate George) as much solids as they did.

For those who recall the discusion a while back regarding a single pass filter
(one that will remove ALL solids prior to the chem or bio sections).
I now know that such a beast is quite impratical.   I WANTED a mechinical 
filter that was sooo good that it woould prevent the following stages from
getting contaminated by solid wastes (which require cleaning).  Yes troops it
does take me a while to come around but given time...

For some time I have been thinking about using bio contactors as the bio stage
for my filters but never quite got around to building one.  Bio contactos
(called biowheels by Marineland) are water wheels with the bacteria growing
on the paddles.  These paddles are alternatly exposed to air and water 
(wet/dry) and if designed properly should not allow solids to build up as in
a trickle filter.

Marineland will soon start shipping a biowheel that can be hooked to a powerhead
or placed on the output of most any pump.  These units hang on the side of a
tank.  I plan to remove the sponge from my sump filters and route the water from
the pump in the sump to the biowheel which will return the water to the tank.

I am not sure where my quest will take me next but it has been interesting.


-- 
Howard Rebel hpcsos.col.hp.com 

From: booth@hplvec.LVLD.HP.COM (George Booth)
Date: Fri, 18 Dec 1992 20:55:02 GMT
Subject: Re: [F] Tough hair algae question
Organization: Hewlett-Packard Co., Loveland, CO