A comment on your biological vs mechanical filtration attributes. From my
understanding, the characteristic of catching organic matter actually
falls under 'mechanical' filtration. Also the removal of visible
particulates comes under mechanical. Biological filtration is the
'warehousing' of the nitrifying bacteria to remove ammonia, nitrites and
even to some extent nitrates. Your description and advice were bang-on,
but the I think that the conventional description would be that they are
poor biological filters and only coarse mechanical filters. The attribute
to make them better mechanical filters (better water polishing) is a
tighter weave of sponge media, which also has more surface area, more
bacteria and is a better biological filter.

Thanks for the info. I sent eMail to Tetra and asked some of those
questions yesterday. I have not received an answer yet, I will forward it
to the group when they do. Your detailed answered is well taken, as I learn
more about this obsession we call a hobby, I have picked up an several
things including who's opinions weigh in.

You brought light to what I probably was avoiding, hoping that I found the
magic (filtering) pill. I will continue to work on the 80 gallon trickle
filter I am working on. 40 gallons of bio balls & 4" of mechanical
filtration with 30 gallons of reserve space for emergency power outages.

Thanks Again
JOhn