On Tue, 07 Jun 2005 20:34:53 +1200, Peter in New Zealand
wrote:

Elaine T wrote:
Peter in New Zealand wrote:

NetMax wrote:

"Peter in New Zealand" wrote in message
news
I have a medium sized tank which is very underloaded with just three
fish. It's been running like this for about a month now and
everything seems to have settled down and got comfortable. I started
out with a really cheap internal filter that blew lots of bubbles
but didn't seem to do a whole lot of filtering. When I pulled it to
bits to see how it worked I just couldn't see how it was expected to
do anything but the most primitive filtering. I guess you get what
you pay for, and it was cheap. Recently I installed a Hagen Stingray
internal filter. I keep it running all the time and the filtering
and circulation it provides is wonderful. My question is this - does
increasing the filtering increase the practical capacity of the
tank? In others words can I carry more fish comfortably? Obviously
there would be a practical limit to all this, but within reasonable
limits would this be a correct assumption? The Hagen has plastic
foam, for biological filtering I presume when the bacteria get
established, and two activated carbon cartridges. Thanks for any
comments - I really am a little new to all this.

--
Peter in New Zealand.
Pull the plug out to reply.




You would need to specify how many gallons your medium tank is for
more specific advice, but if I recall the design of the Hagen
Stingray, I don't think that would keep up with only one Jar Jar
Binks, and I don't know what your other 2 fish are. If all three are
goldfish, then your aquarium is between 30 and 60g and generally
speaking, will need more than average filtration (goldfish!).

Generally, increasing the filtration (by adding more filters) will
increase the tank's capacity, however whether this is a practical
increase depends on what the next constraint is. For example, in a
tall narrow tank, an early constraint is the re-oxygenation of the
water. Extra filtration might help (extra turbulence at the surface),
but you would get into trouble faster during a power failure, so
might not be a practical increase.

Another example is substituting the only filter with a much larger
filter (on any tank). Any single mechanical failure would more
rapidly adversely affect the fish if you had added more because of
the larger filter.

A last example is that adding more fish load creates more waste,
which extra filtering will help with but only to a point. You would
need to also increase the other maintenance (gravel vacuuming, water
changes) to address what the filter cannot help with (solid waste
accumulation and dissolving back into the water).

As a general rule (which works nicely with goldfish), if you need
filtration for a 40g, then use two filters, each rated for a 30g and
clean them on an alternating schedule.



The tank is a 37.5 litre, which I think converts to about 10 US
gallons, and the other two fish are humble little goldfish. The three
each average about 5 to 6 centimetres long, including tail. I have an
UNF with two risers driven by an air pump that runs continually, as
does the Stingray, so I assume aeration is not an issue. It's not a
big tank I agree, but it does look rather underpopulated. I had hoped
to be able to slowly ramp up to about ten or twelve of the little
fellas in there. At the oment after about a month's running the fish
are happy, crap on the bottom is minimal, ph is steady at around 7.2.
What do you think? Can I hope to increase from just three little
inmates? Thanks.

Healthy goldfish grow rather large and put out a lot of waste. Believe
it or not, goldfish fanciers like to allow 10 gallons per adult fish.
Your fish are juveniles, but goldies can grow pretty quickly given clean
water and good food. I personally wouldn't add any more fish to that tank.

Hoo, ah, well, that's disappointing. You don't think their growth can be
limited by the size of their environment like some tropicals are?

I wouldn't count on it. I only have tropicals, but I do have 3 ten
gallon tanks. I have 2 Clown Loaches and 1 Siamese Algae Eater in one
of the 10 gallon tanks (along with 3 platties and 1 molly). All are
moderate sizes.

I think air bubblers are more efficient to increase the oxygen in the
tank water.

I have my own home grown attitude about filtration. I believe the
filtration is really a strainner, that is it holds larger solids, but
the constant flow of water erodes the larger solids down to smaller
sizes that then continue through the filter media. If so, why filter?
I think the smaller particles are more efficiently reduced by the
bacteria in the tank.

Why not use the solution lots of us use, buy a larger tank!
(Of course this would be set up in addition to your existing tank)

dick