What Is a Fish-Only With Live Rock System?
A fish-only with live rock (FOWLR) saltwater system is much like a fish-only system. Just the same no corals are present, but here are the basic differences between these two systems.
- Live rock is added instead of non-living rocks, corals and other decorative items.
- The selection of tank inhabitants is of course based on compatibility, as well as whether or not an individual is going to use the live rock solely for biological filtration and visual appearance purposes, or also wants to propagate the many types of marine organisms associated with it.
- To grow coraline algae, appropriate reef supplements are added.
The Basic Elements of a FOWLR Aquarium
The basic elements that are most important to this or any type of saltwater aquarium is sufficient biological and mechanical filtration, good water movement, and lighting, which depending on the purpose of live rock is where the difference comes in. When the live rock is for biological filtration and visual appearances only, then standard FO system lighting is fine. If a true live rock environment is desired, more intense lighting is needed, which can be provided in various ways.
- If you already have standard output fluorescent bulbs in an existing light strip or strips, replace them with higher output fluorescents such as 10k, 20k and 50/50 bulbs.
- To attain more lighting if you have a single bulb light strip, add another unit, or replace it with a multiple bulb unit with HO tubes.
- Use PC (Power Compact) lighting.
- Light Buying Tip: To save money, if you think you might want to convert a FOWLR system to a reef tank in the future, at the time you set up the aquarium consider buying lighting that will support corals.

