Hi guys im currently collecting items to get properly set up, got my bags of cat litter,co2 bottles,fluval 206 external filter(bought today from a carboot sale boxed never been opend £20). i think all ill need is a reg,selanoid,bubble counter kit/diffuser. The plan is to drain my four foot tank and lay the cat litter with black gravel cap and refill the tank. The only things i feel unsure of are what regulators to buy and do i buy ferts that are liquid that you just pop into the water or do i need to add something into the cat litter aswell as anything else. Also would the external filter be good enough to run a 48Lx18Hx15D. Recomendations on ferts,regs or just a genral set up process