Peter in New Zealand wrote:
Elaine T wrote:

Peter in New Zealand wrote:

NetMax wrote:

"Peter in New Zealand" wrote in message
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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?

The growth of goldfish is limited a bit by tank size. However, it's not
limited enough to keep 12 goldfish into a 10 gallon tank, and even three
is likely to be problematic. Under good conditions, adult comets can
reach 8" SL and even if they grow slowly or stunt, you are still likely
to end up with three 3-4" SL fish crammed into a 10 gallon tank (if none
die along the way).

If you're really set on having a large number of coldwater fish, return
the goldfish and get 10 white cloud minnows. They live well in cold
water, shoal attractively, only grow to an inch or so, and are fun to
watch as the males display to the females.

--
Elaine T __
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