Small water volume present stability issues. Sand seems to help however if you prefer bb in frag display and you have a sump then you can have additional live rock in the sump and/or even sand in sump as a remote sand bed , Knowing the vairiable issues, allows you to determine whether 1. To utilize a doser , or 2. use a calcium reactor or 3, kalkreactor. With small water volume, dosers seem to do well and kalkreactor may do well also. Also need to consider nutrient export so choices are protein skimmer or algae scrubber as well,as water changes. Flow is important so flow should be consistent with large systems--lots of flow for good food dispersion and to provide good water movement. Maintaining salinity will likely require an ATO also. Lighting needs to be supportive for growth which means either mh, t5's or LEDs or a combination thereof. Depending upon flow, lighting and equipment utilized anticipate the need for a heater and perhaps chiller . Independent isolated frag tanks require all the same concern and care as your display tank and will typically require similar equipment and care. Some of the equipment described can be replaced with manual effort like dosing or top off. You still will require frequent testing atleast until stable and still much more testing frequency than on you display because as previously said, smaller water volume tends to result in more rapid shifts in stability
