I would question that. I have a biocube and have had absolutely no problems with the trickle filter. There are no design modifications necessary other than perhaps replacing the filter material with phosban or live rock if you want. As long as the trickle filter is maintained properly it works really well for salt water IMO. The live rock in your tank is sufficient anyways for biological filtration. The biocube at the local LFS vastly outsells all other brands and currently is not in stock as it is the only brand which is constantly sold out.
I've read a lot about people having trouble keeping the water level correct in the Biocube. I have an Aquapod & a JBJ Nano cube. I prefer the Aquapod over the JBJ.
I work in a fish store and we have had problems with jbj and their warranty they do not like to honor it at all. They still have a problem with cracking tanks and notes in there warranty that they do not cover there tanks. So the owner quite carrying their product. The aquapod seams fine as it goes though I would an extra power head in the filtration to push water through the bio and carb media. If you have a chance email jbj and ask a question and see how long they take. I did and it has been over a week and no response.
Holy crap, I have a jbj too, the lights stoped working about 5 hours after my neighbor gave it to me when he moved... the lights shut off, one of the fans conked out too... it's a 24 gallon lol... I'm stillt trying to figure out whats wrong with it.
From what i understand if the ballast goes out it will keep the fan from running i think the two are interconnected. The sunpaq retrofit should fit. I hope that helps.