I recently purchased a Topfin Large undergravel filter. I am getting an Aquaculture 20-60 gallon air pump to run it. My questions are what is the best way to install this in an already full tank? And can I use this later on in a saltwater tank? Any advise is appreciated.
Also, I realize it's dumb I got this after I have had my tank going about a month now, but later rather than never right?
UGFs generally end up being more trouble than they are worth. While they do perform their function very well, it will end up causing more problems than it's worth down the road imho.
Firstly, if you ever want to change your substrate when you have a UGF you are pretty boned because your entire bacterial colony lives on your gravel and you will restart the cycle.
Second, It's impossible to have sand with one if you decide you want sand down the road.
Third, It's nearly impossible to clean out without completely tearing down your tank. The layer of detritus that sits down there will cause nitrate issues down the road. This is the biggest issue in my mind.
Fourth, live plants are completely imconpatible with UGFs. Their roots will completely clog the filter.
As for using one in a salt water tank, it's a very bad idea. Mainly because of issue number 3.
I know that wasn't your question and i'm sorry for going off on a tangent but those are my thoughts on them.
As for installing one, the only way is to completely pull everything out of the tank including fish and removing the substrate. That's the only way to put one in.