hi i have bio balls in my trickle filter on my 30g nano reef and was wondering if they are actually a good idea or not

yeah they work. trap detritus, get a biological media that does the same thing but removes nitrates. a pre filter pad and some cheato sound good. (Good rubble is also better still traps detritus). My not try SantaMonica's turf algae filter. That does work. In any case if you remove bio balls and upgrade do so slowly.