What is a Freshwater Refugium?

What is a Freshwater Refugium?

Given the immense popularity
of refugia in the marine aquarium hobby, you might be left wondering if they
work in freshwater systems. While they haven’t quite caught on yet on the
freshwater side of things, they are just as applicable.


Freshwater refugia do indeed
serve the same purpose: Remove excess nutrients from the water (thereby
reducing unwanted algae growth) and support large populations of small
crustaceans (copepods, amphipods, ostracods, etc.). If there is any real
difference at all, it is in the type of “plant” used. Marine refugia rely
principally on macroalgae whereas freshwater refugia use mainly true plants.


There are so many aquatic
plants available that it is surprising that freshwater refugia aren’t more
widely used than their saltwater counterparts. Some types, though, are better
than others. Slow growers such as Cryptocoryne, for example, might not
be the best choice. Big, leafy, self-shading varieties like Anubias aren’t so great either. Mosses, worts and other tiny types of plant are just
too messy and difficult to contain properly.


Better types
include tall, fast-growing, deeply/densely rooting types that don’t mind living
in thick clusters. These are regularly harvested in sections (either clipped
back or pulled at the root) to allow for continuous growth. Thus, plants like Vallisneria, Stuckenia and Elodea work spectacularly.


Now, just
because a plant could work well in refugia doesn’t necessarily mean that
it will. For the high growth rates, you’d want in a refugium, you must
provide very intense lighting to support optimal photosynthesis. A mineral-rich
substrate can’t hurt, either!


Refugia are suitable for all types of freshwater
systems. Though it might seem counter-intuitive, they work really well on
planted systems. Why? Partly because they provide a huge, regular supply of pods,
which keep the leaves of plants in both tanks (main and refugium) clear of
detritus and fouling algae (fish in the main tank would eat all the pods
without a refugium!). Also, when maintained on a reverse light cycle, a planted
refugium helps to maintain a stable pH throughout the whole system, day and
night! For sure, refugia are destined to gain acceptance among both beginning
and advanced freshwater hobbyists.tr
    • Related Articles

    • How Big is a Refugium?

      A refugium must be large enough to function properly. That is, not just keep a bed of macroalgae alive, but also provide enough space to allow for continuous growth. Without continuous growth, nitrate and phosphate removal ceases. Worse, if an ...
    • Do I need a Refugium?

      A little bit of aquarium maintenance is not only unavoidable, but it can also be a fun way to do some satisfying work and stay involved with your tank in particular and the hobby in general. But, in some cases, an aquarium system never seems to get ...
    • How Does a Refugium Work?

      A refugium is an auxiliary tank that is connected to the “main” tank. While the main tank is used mostly for display, the refugium serves mainly utilitarian purposes. In short, refugia naturally turn unwanted materials such as dissolved and ...
    • What Does A Refugium Do?

      Refugia continue to become more and more popular in the marine aquarium hobby. This is in large part because of a growing reliance on natural water filtration/treatment methodologies. But, mainly, this is because they actually work. The typical ...
    • Can I Put Fish in My Refugium?

      So you’ve got a big, healthy refugium attached to your main tank. Just sitting there, without much movement in it (well, aside from thousands of little scurrying pods). Especially if your main tank is chock full of fish, you might start to wonder: ...