im running one TETRA EX70, AQUACLEAR 30 and a ehiem 2215 on my 60 so IMO one filter is not enough unless u have a small stocklist! i would recommend 2 AC110s like deathsting said
i run an xp3 on my 55. keeps the water crystal. supporting 3 bristlenose, a gibby, a large cat fish (about 25cm) and a few others with no problems. highly recommended.