I have been keeping saltwater aquariums since bioballs were one of the main sources of biofiltration. As long as your rinsing off your bioballs every month or two, it won’t be the main source of your nitrate issues.
Assuming you have the plastic bioballs.
The only time bioballs become a problem is if you allow them to build up with all the gunk without rinsing them off.
When doing water changes, just rinse off the bioballs in a bucket filled with your old water, you won’t have any issues with bioballs as long as you rinse them off occasionally.
Once a month is probably plenty, as long as your not majorly overstocked or feeding really heavy.
Your tank is also fairly new, it usually takes a good year for a tank to fully mature.
Carbon dosing will control any nitrate issues you are having. You just have to ramp up your dosing to the proper amount.
I dose vinegar, works well, it’s cheap and also provides a food source for corals.
When I rebooted my 210, my nitrates skyrocket off the charts, test kit was blood red, off the charts. I am 99% sure it was due to the rock sitting around for a few years until I was able to start the 210 back up.
Regardless, carbon dosing got the nitrate under control.
Personally, I would just dose either vodka or vinegar. I had always used vodka in the past and it worked well, but, when I rebooted the 210 I started using vinegar as it’s also a food source for the corals.
Anyway, that’s my 2 pennies on the subject
