Add a heater, remove the bio-balls, trim the baffle between chamber 1 and 2, remove the false floors, and add a light and some more macro in the middle chamber... Otherwise, just stick with water changes (tough line to toe in such a small volume -- too much and its a hard shift in ionic balance, too little and you achieve little results...) I tend to do 1 gallon per week in my BC8 (w/ rock, probably about 6 gals of water -- a bit over 15% per week).. My biggest fear is the bioload that the cube would take on -- clearly the last pair had an adverse reaction (perhaps it was a side effect of no heater?)...


If it were me/mine, I'd add to the display and forego the 'hardening' in the biocube..

-Justin