3 gallon questions


Junior Poster
Jan 22, 2010
I'm new to planted aquariums and am having trouble finding information on freshwater nano tanks.
I have a three gallon tank which I'll be keeping one dwarf puffer in.
What C02 system would be ideal for a tank of this size?
Also, how should I manage filtration and flow? Would a small hang on back filter suffice?

Thanks for your help,


Junior Poster
Dec 23, 2009
South Carolina near Charlotte, NC
Hi Maddie, I am a newbie as well. Yes, there is not much info out there on nano-aquariums. Maybe nano-reefs that I have seen and very inspiring. Nano systems are quite a challenge, an apparent small change can become multiplied dramatically in the small volume. My first question would be why do you need CO2? have you read Tom's article on step 1 and step 2 in newbies area? also the newbies thread? There are also great low tech non-CO2 options as well (yet another thread) that do not inject CO2. Step 1: Define your goals is a great article. I cannot recommend it enough. Form follows function. Wish I had found it a few years ago before I designed a system. In the non-CO2 thread, though I do not subscribe to the Diana Walstad method (though an interesting concept and philosophy), there is some great low-tech info there as well. In reference to the Walstad method, I do not believe we can actually have a natural system (biologically) at all, because by its very nature an aquarium is an un-natural system cut off from nature: no rainwater, no leaching minerals and nutrients from the sediments, totally unattainable precipitation, evaporation and erosion patterns in an aquarium of any size. And that is just the H2O cycle, not to mention the biosphere and other concepts like nature's carbon cycle. Aquariums are dependent on a human being to maintain them. Nature? not so much. Actually the opposite is true. I do think that more water=more opportunity to recreate a natural system though. There are some beautiful public aquariums out there. Anyway, here are some great articles I have found very helpful.



Regardless, I do have a 7-gallon nano and currently use the Hagen Natural CO2 (DIY yeast mixture) with their rail diffuser. It really is NOT the ideal method: the rail diffuser is the problem in that snails, plants, and other intrusions disrupt the flow, as well as a very small canister that only produces for about maybe 2-3 weeks. I am in the process of experimenting with a new diffuser in the next few weeks. The CO2 fert threads are also outstanding so I am learning a more technical approach that will give me consistency. DIY vs Bottled CO2. And reactors. Etc. I still have A LOT to learn about CO2/High Light set up. I have had limited success in the past; but doing much better with it using the EI method so far. I am also looking for better CO2 models to use in my nano and look forward to following your thread. Hopefully more posts or recommendations will come soon. Thanks for posting!