Propagated corals can easily be placed within the main system from which they are propagated. There they can be allowed to grow out, to be sold or traded at a later date. However, for the more serious coral propagation farmer finding room within the main display system may quickly become a problem. The sump is another option, but that would require intense lighting usually under the display system which caused additional challenges, not to mention dealing with equipment and other obstacles within the sump. There is another solution however.
A small display aquarium or even a plastic container of almost any sort can be modified to fit any type or size system. The use of egg-crate can be of particular use when constructing a "frag tank".
This particular system is only about 12-inches deep. While seemingly shallow, this depth (or even less!) is ideal to our need as coral farmers. Many advanced hobbyists keep systems completely separate from "mother" systems from which the fragged coral is removed. In my opinion, except for in very large operations, this decision may actually be counter-productive.
Almost immediately even before actually severing the the coral, the frag (not to mention the entire colony) is stressed. Cutting and reattaching the frag to its new base also adds to this stress, as does any time actually out of the water and the recovery process itself. This is why I feel it ideal to maintain the newly removed frag(s) in the same system water.
To achieve this, a small container or tank like the one above can be piped into the main system as an auxiliary system. This auxiliary system can even be beneficial to the main system in the form of added water volume, additional surface area for gaseous exchange. If this system is lighted opposite the main system, it can also be utilized as a manner to control pH fluctuations which occur heaviest at night when the lights are out. Lighting a shallower depth is also much easier and can even be lit by standard household bulbs in some cases.
In the very near future, I will discus the use of "raceways" as applied to coral propagation. They may very well be one of the very best methods for maintaining small corals and newly separated frags with low volume water. Additionally, I will discuss proper placement of newly acquired frags in the propagation tank, as well as show a few pictures of my particular setup. In the meantime, I would like to recommend an EXCELLENT book on the subject. It is entitled "Book of Coral Propagation - by Anthony Calfo. Please keep in mind that I am in no way affiliated with Anthony Calfo, his publisher or any other aspect of this publication. It is just simply the best publication I have found on the subject and cannot go without mention.