Welcome back to this hobby! You are right to study Diana Walstad's book before starting up a new tank. You don't need a "bio-filter" because the plants will do the same job for you. A mechanical filter can be very helpful if you get very hazy water or to prevent getting hazy water, and it gives you some circulation of the water through the tank. Ms Walstad's method uses CO2 generated by the dirt in the substrate, instead of injecting CO2. That is enough CO2 if you don't have a high intensity light and don't use the hard to grow plants with wild colors that are very popular in aquariums.Great to meet this community. I'm returning to the hobby and have been heavily influenced by Diana Walstad's book*. I'm looking to establish a new 75 gallon tank but had two key questions:
1. In the book, she doesn't advocate for a bio-filter, but does recommend a UV and mechanical filter. Anyone have good suggestions for a tank this size?
2. I see in the threads the common use of CO2 injection (and my local stores). Ideally, I'd like to avoid this. For an aquarium this size, can I skip that following the guidance in her book?
Looking forward to diving into this and great to find this community.
[I had 5 freshwater tanks and a saltwater as a teenager. Never appreciated planted aquariums. Great to see the hobby take this direction. I also now have an outdoor pond, not as planted, but will improve that]
I like to revisit Ms Walstad's book anytime I start getting confused about what and why she is recommending something. It is organized so it is a very good reference book.