Hi Rush, I went to a local petsmart this afternoon for a few more fish, and a hew hood light. I was looking at and pricing the bigger tanks, and asked the guy at the store what to use in a 50 gallon tank I have so he showed me filters and pumps, but no underground filters, and I didn't ask him about them in that size. I didn't realise they were available. Thanks for letting me know that. My problem is the 50g tank is fours hours away in my old home. But, I have no place for it at the moment, negoiating with the other half on that one still. ha ha I've read that if you use live plants it's not good to use an underground filter, that so? thanks lady.