Was wondering if it is possible to convert a tank from FW to SW without doing a total "teardown" so to say. I'm asking as the water in my 10 gallon is absolutley perfect quality but I've consolidated what I had in it into my 80 gallon tank so it's sitting empty. I was thinking to myself "what oh what should I do with this", then I started reading about nano reefs and realized how great it would go as a small display tank with a pair of clowns in it. I'm set on doing that, but if I'm able to just "add salt" and convert/add/modify what I need to get it going as a SW tank it would save me the time of the cycle.

Let me know, and Thanks.

Thats going to be a problem. Saltwater bacteria is different than freshwater. So once you add the saltwater, it'll all die and have to start over. Also, you'll need to purchase some live rock for that stuff to grow on and to carry it over. So, you'll have to cycle anyway.

K problem solved, will be setting the tank up shortly.

Also wondering about this... I have an old filter sitting in a box somewhere (forget the brand) that I used on a 80G I had at my old place, flow rate is something like 320-400 GPH, would this be ok to use as a combination filter/circulator or is it overkill?