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Re: filterless tanks and blackwater extract


>      1)has anyone set up a planted tank before without a filter and if so
> which plants did u use?  what r also the pros and cons of setting up a tank
> without a filter...

I have three tanks currently running without filters.  However, they
weren't originally setup as filterless tanks.  The were set up as filtered
tanks from which I (years) later removed the filters.  I think its a good
idea to keep at least some very fast-growing plants in unfiltered tanks.
I have good luck with vals, h. polysperma and rotala indica.  Starting
in a new tank, you might want to include plants with a lot of leaf-surface
area.  Mayaca, Cabomba and Myriophyllum species come to mind.

pros and cons...

   a) filters (even most of those not intended specifically as biological
filters) host nitrifying bacteria that compete with plants for ammonium.
Without a filter the ammonium *should* be more available to plants.  The
down side of this is that "more available" necessarily implies a higher
ammonium concentration, but I tested ammonia/ammonium repeatedly after
removing the filters from my now-unfiltered tanks and never once found
enough ammonium to measure.

   b) filters remove sediments from the tank that might contain plant-
available nutrients, or nutrients that will become plant available if they
are left in the tank.  The down side of this is the same as the up side;
the sediments remain in the tank.  See the "downside" for c).

   c) there is less maintenance, because you don't have to clean or
otherwise mess with the filter.  Of course, it does result in more
sediment remaining in the tank and might increase the amount of cleaning
you have to do in the tank.  Personally, I siphon out anything that
becomes an aesthetic burden and I haven't found that removing the filter
increased the frequency of cleaning.  It did increase the amount I removed
during cleaning.  If you don't currently clean on a frequent basis, then
you may need to do so.

   d) if you want to keep filter feeding-animals then you probably should
not have any kind of mechanical filter on the tank.  This implies an
increase in the amount of suspended sediment.  The amount of sediment in
my unfiltered tanks is probably about the same as it is with an aquaclear
filter using a coarse sponge insert.  It is certainly more suspended
sediment than you would have with a fine filter material in a canister
filter.

   e)  Unfiltered tanks generate less noise than at least some filtered
tanks (depends on the filter) and they may be less turbulent (also depends
on the filter).  You probably won't be able to get away without some means
of providing circulation in the tank, so the gain here could be small.

>      2)how can i disperse the CO2 bubbles around the tank so that all the
> plants benefit from it and it doesnt just leave the water?

As in e) above, you probably will need to provide some circulation.  I use
powerheads to circulate the water, and have my CO2 outlet below the pump
inlet so the pump sucks in the CO2 and disperses it through the tank.  My
CO2 setup produces small, frequent bubbles so the setup makes about as
much noise as a ticking clock.

>      3)is there anything else i need to know before setting up this tank?

I've heard it claimed that suspended sediment can contribute to disease in
some cichlids and possibly in some other fish.  I don't buy that story
myself and tend to attribute problems like that to other types of stress
rather than to the presence of a vector that exists anyway in the fish's
natural environment.  I can imagine though, that some very weakened
strains of fish like fancy goldfish or highly inbred discus may be
susceptible to problems that way.  I don't keep fish like that.

> ------------------------------

On to other things...

> Does any one have any ideas why the Blackwater Extract had such a strong
> effect on accelerating the plant growth? The ingredients are listed as
> Vitamins B2, B6 B12, nicotinic amide, panthenol, biotin and peat extract.
>

I haven't used the product, so this speculation is based solely on the
list of ingredients you provide.

I've read that plants will use some biochemicals from their environment
rather than trying to synthesize all of their needs from scratch.  Some
cellular precursors might actually be essential for some plants, and
certainly must be for other organisms in the aquarium - other organisms
that could be key to cycling nutrients for your plants' use.

Some of these biochemicals (I've read of thiamine in this context) could
actually be growth rate-controlling nutrients.

This is largely speculative, but it's a speculation that I've entertained
for a couple years now.


Roger Miller
Comfortably basking in desert sunshine.