Nice that you are interested in nano tanks!
Personal thoughts:
I personally use Fluval Spec series tanks, because they provide the best filtration system out of the many all-in-one nano tank options (I overstock them with nano shrimp/fish species) and the tanks are widely available in local pet stores. Fluval also has other nano tanks, but the Fluval CHI has poor lighting and the Fluval EDGE is hard to maintain because there is a small opening to access the inside of the tank. The Topfin and Fluval Spec also have a longer surface area which will provide more horizontal swimming space for keeping fish/shrimp. However, I know that the Eheim Aquastyle tanks have slightly higher wattage lighting for plants, and the SOLO tank has an interesting multi-colored lighting feature with a remote.
Pros:
- Excellent integrated filtration (it can easily fit extra Purigen, filter floss, additional biomedia)
- Very long surface area (lots of horizontal swimming room for livestock, unlike nano cubes from Eheim or Current)
- Built-in sump that hides the equipment well
- Very sleek design (you can remove the top cover to make it look like a rimless tank)
Current cons that I personally find with the Fluval Spec tanks:
- Lower wattage lighting (this was not a major issue for me because I do low-tech environments, but there are many lighting mods or upgrades that you can do to make it a high tech tank with CO2 injection)
- You need to find a suitable heater that can fit in the built-in filter sump (I use the Marineland ones from J & L Aquatics, or you can use the Hydor mini ones that can be found online).
- Water flow can be overpowered for Bettas and slow-moving fish, but you can reduce the flow settings or add some filter floss in the nozzle
- I have to put some fine mesh over the filter intake and grill to prevent suicidal/adventurous baby shrimp from making a home inside the filter
This is a very useful website, product review, & mod guide to the Fluval Spec Nano Tanks:
Spec-Tanks - dedicated to the nano aquarist
Here are some pictures of my current setups with the Fluval Spec Nano Tanks:
Twin Fluval Spec V Low-tech Nano Tanks - The Planted Tank Forum
Purchase locations:
- Fluval Spec Series tanks can be found in almost any pet store in the Lower Mainland or online
- Solo 5g and Eheim Aquastyle can be found at J & L Aquatics in Burnaby
- Topfin brand nano tanks can be found online mainly, but they may appear at Petsmart.
Notes:
Since you are planning to do a
nursery/breeding tank, I am assuming that you are focusing on the health of baby fish/shrimp instead of primarily high-tech plants. You should choose a nano-tank that offers the
best filtration system and
horizontal swimming space, instead of choosing a tank only because it has nice aesthetics or high lighting wattage for plants.