I have a fx5 with foam and the bio balls in the center parts of each chamber. The 2260 has the white string like stuff in it now but I was wondering would filling it with bio balls be better?
I would use something other than bioballs which is mainly for wet dry aps...
Seachem matrix will cost you about $110 for a five gallon bucket(you'll have some left over) or 15L of eheim substract pro for around $160(you'll need 3L of mechanical substrate in addition) is your best bet IMO.