Hello everyone,
I've been keeping and breeding various tropical fish for a while now, focusing on species that thrive in very specific, low-pH, clear water environments. My main focus has been on wild-type Bettas and the beautiful German Blue Ramirezi (Mikrogeophagus ramirezi), but I’ve also successfully bred Cardinal Tetras (Paracheirodon axelrodi)—though the effort vs. reward for the Cardinals in Europe is low, especially when healthy, cheap stock is available from places like Czech farms selling direct.
The common thread between all these fish is their origin: they come from slow-moving backwaters, pools, and side arms of tropical clear-water rivers, characterized by extremely soft, acidic water and often very minimal current.
This has led me to a long-standing question: Where exactly does the benefit of elaborate aquarium filtration end, and where do the aspects of a truly still water environment become more beneficial for these biotope-specific species?
My filter experiences so far:
I’ve experimented with various filter types over time:
Large Canister Filters: Always felt excessive. I typically used minimal media (maybe 20% capacity) and often baffled the output to just use a fraction of their flow capacity, making them feel like an over-engineered solution for a stillwater setup.
Small External Filters (Hang-on-Back/HOB): Cost-effective, practical, and offer the right low-flow rate. However, they clog quickly, and cleaning can be fiddly.
Internal Filters: Can work very well, and many are shrimp-safe, but they inevitably take up valuable space in a smaller breeding tank.
Air-Driven Filters (Sponge/Box): Too loud for my preferences, and critically, they are CO2 strippers—a definite no for my heavily planted, low-pH tanks.
Surface Skimmers Only: I still use these in the initial setup phase to promote circulation and break the protein film/pellicle. I only run them intermittently or as needed once the tank is established.
The Stillwater Advantage:
Microfauna and Filtration
Here’s my major observation and the core of my discussion:
What is the unseen cost of most mechanical filtration?
I strongly suspect that certain beneficial microfauna populations—especially Cyclops (copepods) and various tiny crustaceans that inhabit the water column—are negatively impacted by constant, strong filtration.
In my truly low-flow or filterless, well-established tanks (usually run with just a skimmer for occasional circulation), these micro-organisms absolutely thrive. And they are not just free-swimming live food; they are active cleaners!
Observation: In these mature, stillwater setups, I rarely, if ever, have to clean the glass. If the tank is running optimally, it looks pristine, as if freshly cleaned, without me lifting a finger.
Furthermore, I’ve noticed a significant difference in fry survival and growth rates. Fish larvae (especially the sensitive Betta and Ram fry) fare much better and grow faster in these well-established, low-flow environments. I attribute this partly to the constant availability of natural micro-invertebrates as a first food source, which the parents either miss or ignore.
Discussion Points:
Do you deliberately try to minimize flow in your specialized low-pH/blackwater setups?
Have you noticed a correlation between the development of beneficial microfauna (Cyclops, Daphnia, etc.) and low/no-flow tanks?
Are we over-filtering—mechanically and biologically—for fish that inherently come from biotope conditions that lack high flow?
Looking forward to hearing your experiences and thoughts!
Greetings from Germany, Felix
I've been keeping and breeding various tropical fish for a while now, focusing on species that thrive in very specific, low-pH, clear water environments. My main focus has been on wild-type Bettas and the beautiful German Blue Ramirezi (Mikrogeophagus ramirezi), but I’ve also successfully bred Cardinal Tetras (Paracheirodon axelrodi)—though the effort vs. reward for the Cardinals in Europe is low, especially when healthy, cheap stock is available from places like Czech farms selling direct.
The common thread between all these fish is their origin: they come from slow-moving backwaters, pools, and side arms of tropical clear-water rivers, characterized by extremely soft, acidic water and often very minimal current.
This has led me to a long-standing question: Where exactly does the benefit of elaborate aquarium filtration end, and where do the aspects of a truly still water environment become more beneficial for these biotope-specific species?
My filter experiences so far:
I’ve experimented with various filter types over time:
Large Canister Filters: Always felt excessive. I typically used minimal media (maybe 20% capacity) and often baffled the output to just use a fraction of their flow capacity, making them feel like an over-engineered solution for a stillwater setup.
Small External Filters (Hang-on-Back/HOB): Cost-effective, practical, and offer the right low-flow rate. However, they clog quickly, and cleaning can be fiddly.
Internal Filters: Can work very well, and many are shrimp-safe, but they inevitably take up valuable space in a smaller breeding tank.
Air-Driven Filters (Sponge/Box): Too loud for my preferences, and critically, they are CO2 strippers—a definite no for my heavily planted, low-pH tanks.
Surface Skimmers Only: I still use these in the initial setup phase to promote circulation and break the protein film/pellicle. I only run them intermittently or as needed once the tank is established.
The Stillwater Advantage:
Microfauna and Filtration
Here’s my major observation and the core of my discussion:
What is the unseen cost of most mechanical filtration?
I strongly suspect that certain beneficial microfauna populations—especially Cyclops (copepods) and various tiny crustaceans that inhabit the water column—are negatively impacted by constant, strong filtration.
In my truly low-flow or filterless, well-established tanks (usually run with just a skimmer for occasional circulation), these micro-organisms absolutely thrive. And they are not just free-swimming live food; they are active cleaners!
Observation: In these mature, stillwater setups, I rarely, if ever, have to clean the glass. If the tank is running optimally, it looks pristine, as if freshly cleaned, without me lifting a finger.
Furthermore, I’ve noticed a significant difference in fry survival and growth rates. Fish larvae (especially the sensitive Betta and Ram fry) fare much better and grow faster in these well-established, low-flow environments. I attribute this partly to the constant availability of natural micro-invertebrates as a first food source, which the parents either miss or ignore.
Discussion Points:
Do you deliberately try to minimize flow in your specialized low-pH/blackwater setups?
Have you noticed a correlation between the development of beneficial microfauna (Cyclops, Daphnia, etc.) and low/no-flow tanks?
Are we over-filtering—mechanically and biologically—for fish that inherently come from biotope conditions that lack high flow?
Looking forward to hearing your experiences and thoughts!
Greetings from Germany, Felix
