Setting up a tropical freshwater aquarium using the
Fishless cycle method.
So many beginners often fall into the trap of setting up a tank and
stocking it with fish too intolerant of poor water conditions that I
promote the use of a fishless cycle method where ever possible. Mainly
for two reasons, firstly it means that at the end of the cycle you can
stock the tank to capacity with the fish you actually want to keep and
not platys or mollies. And secondly, you are not putting any fish under
duress by having to suffer high ammonia and nitrite levels.
So how do you cycle a tank with out fish? The answer is by using
ammonia to start off the production and growth of the bacteria in the
filter and gravel bed. However you can’t use any ammonia. It has to be
pure and free of any scents or other compounds that could poison the
tank. The product I used (and several other members of various message
boards) is Amo Kleen Household Ammonia made by Barrettine and
manufactured by Woodman Hill Ltd (telephone 01923 233977). It
should be available through your local chemist or hardware shop.
The above product contains nothing but ammonia and distilled water
at a 9.5% solution, i.e. 9.5 parts ammonia to 90.5 parts water.
Obviously this dilution will affect the amount of drops you add to the
tank. If you obtain a different product with a higher concentration
then you will need to add less to the tank, or more if the concentration
is less.
Now you have the ammonia there is one other important item needed.
A good freshwater test kit for ammonia, nitrate, ph, and nitrite. I
recommend the API master test kit that has all these test kits in one box
for a lot less than buying the individual test kits. Typical price is £15
- £23 depending if you buy on-line or at your local fish shop.
Starting the cycle.
Set the tank up with all the equipment, gravel, filters etc as normal.
You can plant your tank with living or plastic plants at the start;
however it is advisable to have the tank running without plants for 24
hrs to bring the water up to temperature and confirm that the
equipment is running OK
Having planted the tank and confirmed that the water is up to
temperature, and all the equipment is running; now you can start the
cycle. I used a small pipette and counted the number of drops I added
to the tank. To give you some idea, these drops are the same size as the
reagent test bottles produce. I started with 20 drops and then let the
water circulate through the tank and filters for a while before I tested
the water for ammonia. I then repeated this process until the test
recorded a level of 5ppm (parts per million). I had added a total of 75
drops to the tank which by simple maths gave 15 drops to raise the
level 1 ppm. As I was recording the complete cycle I also tested for
nitrite and nitrate too, but this is not required from day 1.
The next day test the tank water for ammonia. Chances are the reading
will be the same as the day before with 5ppm. You should also test for
nitrite too which will show a level of zero in the first few days.
Test again each morning and normally around the third or forth day
you will notice that the ammonia level has decreased and the nitrite is
rising. Now using your calculation you need to add enough drops of
ammonia to raise the ammonia level in the tank back up to the 5ppm
limit. I found that it was best to add a few drops less, say 10 drops, to
verify that the maths is correct (which it was).
During the first five to seven days you will see the level of ammonia
steadily fall each day when you do your tests. You will also see the
levels of nitrite steadily increase. So you will need to add more and
more ammonia each day to bring the level back up to the 5ppm limit.
Continue testing each day, and adding ammonia to maintain the 5ppm
limit. You will notice that having peaked, the nitrite will start to fall
back down to zero. For me this was around about day 13, but this will
depend on the size of your filter etc so it may be sooner, or later, but it
will happen. At this point I cut back on the dose of ammonia I added
to the tank each day. Instead of adding the normal dose, I added 50
drops per day every day until the first water change.
Once the nitrate level has peaked and dropped back to zero, start to test
your nitrate levels too. They should be fairly low, but will start to rise
at some point. My levels started to rise around day 17. When the level
was 40ppm or above I stopped adding ammonia to the tank and
performed a 50% water change. Using a good de-chlorinator that also
treats chloramines too, the fresh water was added to the tank and the
tank left for 24 hrs before testing one more time
The next morning the ammonia was zero, the nitrite zero, PH stable at
7.6, and nitrate 40ppm. The issue with the nitrate is down to the fact
that it comes out of the tap at this level, so until I can cut it with some
RO water I’ll have to live with it.
Now is the time you want to stock your fish, as you need the ammonia
in the tank to maintain the cycle. If you are not ready for stocking yet,
simply add some ammonia to maintain the 5ppm level, and then do a
25% water change the day before you want to get the fish.
I was stocking a community tank with small fish, so I stocked almost to
the old saying of 1” of fish per gallon of water, but obviously this
really depends on the type and number of fish you keep. For example a
large cat fish may only be 12” long, but it will produce far more waste
than twelve 1” neon’s tetra’s.
From then on your fish will provide the source of ammonia to
maintain the cycle. You may note a slight change in the water quality
a few days later depending on the stock levels and type of fish you
have, as the bacteria adjust to the new bio-load that it needs to
maintain. Often there will be a slight die off as the ammonia level
produced by the fish is probably less than the seeded 5ppm, but don’t
worry, the tank will soon balance itself out.
Here are my test results in the form of a graph:
45
40
Ammonia
Nitrite
PH
Kh
Co2
Gh
Nitrate
PPM / PH / dH
35
30
25
20
15
10
5
0
1
4
7 10 13 16 19 22 25 28 31 34 37 40 43 46 49 52 55 58
Day
In my opinion the advantages of a fishless cycle are:

Its quick – taking typically three weeks to get to the point of fully
stocking the tank

You can stock the tank to its limit in a very short time.
Compared to the traditional way which could take 6 months to
reach the same level.

No fish are stressed or put at risk by having to tolerate high levels
of ammonia or nitrite

You can stock the tank with the fish you want, and not have half
dozen platys that you don’t want and end up breeding line mad!
Obviously, things may take longer in your tank, given that the
variables such as water quality from my supplier, my filtration,
lighting and how densely planted the tank is, are going to be different
from you set up. I also take no responsibility for any damage what’s so
ever should anyone follow these notes. You do so entirely at your own
risk.
M. Crabbe