just got my new 75gal up and running over the weekend. last had a tank running 20 years ago "40gal".well that is not quite true i have had a bait tank running last few winter's(rainbow trout). on the new 75 it only has an under gravel filter(2 power heads/a 50 and a 30)and i am wondering if this will give good enough filtration once it is established. just put in 12 feeder goldfish (nice looker's) to get biologics going. any opinion's would be helpful.thanks.