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.

--
Elaine T __
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