One area of ongoing experimentation by aquarists is the refugium photoperiod. To date, no one has proven that a particular refugium lighting regimen is ideal, at least for all systems. Fortunately, it doesn’t seem like any are harmful! Planted refugia seem to “work” just fine as long as they receive at least ten or twelve hours of intense light per day. Still, some aquarists run their lights 24 hours/day without any apparent ill effect.
One method that is well worth mention here, though, uses a so-called reverse photoperiod. The “reverse” part comes from the fact that the refugium lights are timed to operate “on” while the main tank’s lights are “off,” and vice-versa. The reason for this is that it balances (at least in theory) water chemistry deviation that occurs as a result of the photosynthetic activity of the plant life, both in the main tank and in the fuge.
As you very well may know, plants (including macroalgae) take up carbon dioxide from their environment in order to store energy (i.e. make sugar) as well as to build biomass. Drawing carbon dioxide from water alters the carbonic acid balance such that it raises pH. Plants only do this while carrying out photosynthesis. The result is that (especially in a small, closed system like an aquarium) sharp pH swings can occur between day and night cycles.
In a reef tank loaded with hermatypic corals and clams, you might have a lot of photosynthetic activity happening during the “lights on” cycle; activity in the refugium can add to this if its lights run “on” concurrently. However, if its lights are on alternately, the refugium can perform a beneficial balancing act by stabilizing diurnal (i.e. day/night) pH values!
We only strongly suggest one thing; no matter what light cycle you choose, be sure to use timers because, with macros, consistency is certainly key to their health!
Do Copepods Need Light?
Let’s start by making one thing clear: There are no animals that “need” light in the way that photosynthetic organisms do. Only plants and certain microbes are capable of performing photosynthesis (“photosynthetic” corals and clams, don’t need light, ...
What Kind of Light Do I Need for a Refugium?
Nowadays, almost all refugia have macroalgae and other types of plants in them. This means that they require a light source of their own. Luckily, there are now aquarium lighting systems that are specially designed to provide the very high intensity ...
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 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 ...