canister filters are very costly
can easily be Rm200-RM500
so u better be prepared to fork out money
if u r on a tight budget, can use DIY co2
however, ur tank is so big
so its still better to get a pressurised co2 system
i used to have the same problems as urs
wrong filter, no co2 system
however, i decided to invest some money
i changed my filter(cant afford canister so got myself an Eheim internal)
also got myself a pressurised co2 system with electric solenoid
the effects are wonderful
spent approximately RM600
but never regretted