Jim Morcombe wrote:
A couple of threads have made comments about cycling in a new tank that
I disagree with. For example, that it is impossible to cycle a new tank
without harming the fish and hence you must use "rubbish fish".

I have never lost a fish in cycling in a tank. Probably the main reason
is that I really understock the tank to start off with. Here's my method.

Most of the time I start a new tank is when my fish have just produced
their eggs so I have a couple of weeks notice in order to get ready. In
this case, I put an extra filter into one of my tanks and let it run
there so that is is full of bacteria. Sometimes I don't have this luxury.

I keep my fry in a net in the main tank for a couple of weeks. When I
am ready to give them their own tank, I take the dirty filter medium out
of one of the canister filters and rinse it out in the new tank. The
water turns into a murky grey/green soup. I then put the filter in the
tank and let it run for a couple of hours until the water is a little
clearer. I then dump the juvenilles into the new tank.

The "pond scum" from the canister filter settles all over the bottom of
the tank, making it pretty gross for the first couple of weeks. A lot
gets sucked into the filter, but far from all of it.

Thats it, the tank is now established. After a few water changes, most
of the pond scum has disappeared, but by then the bacteria is well
established in the tank.

With this method, I am putting in much more bacteria in the tank than is
needed for the tank, so the bacteria level will fall as the tank
establishes itself rather than building up.

When I set up a new tank at school for my science students, I often
don't get around to establishing the new filter first, but this doesn't
seem to make much difference. I make a party trick out of making the
water as murky as possible and then dumping a few fish in straight away.
The kids always accuse me of trying to kill the fish and are amazed
the next day to see the fish swimming around happily in much clearer
water. I then use this as a lead in to explaining the nitrogen cycle.

Note that although the bacteria level drops off, the algae in the pond
scum does not, so this does not add to the level of ammonia in the tank.


I have never recommended the cycle products such as Cycle or Stress
Zyne either.
I have always used the media transfer method (although Bio Spira is
different, but neither I nor the service personnel who took over my
maintenance business have used it enough to vouch for it).

I do not believe fish are expendable either and do not set my customers
FW or SW aquariums with this in mind, and I rarely loose any fish in
my new set ups using the media exchange method (as my customers can
attest to)

I have to agree with Tynk as to the squeezing of media. I actually
tested this theory many years back and found ammonia spikes I did not
with the transfer method. I also agree that the media transfer method
adds "food" for bacterial colony (although the pure ammonia method does
this too, but I believe it is slower and can stress the fish)

Carl
Here is one of my nitrogen cycle articles:
http://www.americanaquariumproducts....gen_Cycle.html