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Re: Small 1-gallon tank

Hoa Nguyen <nguyenh at nosc_mil> wrote:

> Has anyone tried to keep a 1-gallon planted tank with no CO2?  I have been
> trying to do that at the office, keeping it near the window (for light).
> It has no filter, air pump, or CO2.  Just a small heater to keep it
> reasonable for the fish, and a 10% water change daily.  In it I keep a
> Beta, 2 Otos, and a bunch of snails.  Plants include Java Fern, Anubias
> nana, and Pygmi chain swords.
> The problem is that the Otos keep dying.  They would be fine, eating a lot
> for a while (the tank had a fair amount of green algae before the otos were
> added, and which the otos have been slowly bringing under control), then
> would have a curved spine, and die.  I think one problem could be the pH.
> The tap water pH is around 7.6, and the gravel has been previously
> neutralized with acid, but the tank water keeps rising to above 9.  I
> wonder if it's due to biogenic decalcification.  The plants I keep are not
> known for that (or are they?).
> Is it okay to add Aquarium Pharm.'s pH Down (Sulfuric acid) daily to
> control the pH?  What would the long term effect be?  (I have not been
> doing that, just thought I would ask first.)
> Does anybody have any idea or related experience to share?

There are at least two basic problems to solve with small tanks and
plants: pH and oxygen. Let's assume that you can keep ammonia levels in
check by the plants and water changes.

It's good that you have sunlight but its best if you can prevent full
strong sunlight from hitting it especially in summer. Venetian blinds
can help to regulate the amount of light. The problem is heating the
tankw ater up so high that there's no oxygen left in the water. You can
also get cyanobacteria in such conditions unless you are changing water
faithfully. The Betta won't mind the warm temps (won't like cold though)
but the Otocinclus won't be able to tolerate low oxygen.

The pH problem can be solved if you use a cotton bag of sphagnum peat.
Aeration is another way to keep the water moving and supply ambient CO2
to the plants. Enough aeration to keep the plants supplied with CO2
adequately would probably stir up anything laying loose on the bottom of
the tank and might disturb the Betta. Peat or peat water buffering keeps
the pH stable so its not necessary to have really vigorous water
movement. With enough water movement (no fish), I think you could keep
the pH stable without pH buffers and still have reasonable plant growth

As an alternative, why don't you go to a 5 gallon tank? This will be
easier to keep stable.

I've been keeping Killiefish in small tanks for a couple of years
without filtration. I use Ceratopteris and Salvinia as they grow
rapidly, consuming ammonia and getting CO2 from the air. The Killies
also breed in the plants. Regular water changes are important as is peat
to keep the pH stable. The peat should be replaced periodically, say
every 3 months. It helps if you provide aeration to the tank to keep
oxygen levels up and help prevent BG algae. The lighting must be strong
enough to keep the plants growing. You must not overcrowd a small tank.
1 gallon per fish in a planted tank seems to be safe for fish upto 2" or
so. I think the fish will be healthier in a larger tank.

Steve Pushak                              Vancouver, BC, CANADA 

Visit "Steve's Aquatic Page"      http://home.infinet.net/teban/
 for LOTS of pics, tips and links for aquatic gardening!!!