nurseturtle wrote:How many L's/grams of bio rings do I need to start w/the Fx5?
Full disclosure statement: I have a 55 gallon tank with a fluval 406 and a refugium, so I have no practical experience to draw on, but from what I have read and researched in preparing for a larger tank, I do agree the FX5 is probably the biggest bang for your buck.
That said, you don't need to buy expensive fluval biomedia. The FX5 holds 6 liters of media, some of which is going to be carbon. Seachem makes claims tha their Matrix media can denitry as well as nitrify. Fluval biomedia certainly works. But, from what I've read, any ceramic media will provide locations for nitrifying bacteria.
If you are in a budget, I'd still recommend the FX5, but save money ont the carbon and biomedia by going cheaper. When you are flush with cash again, you can always replace with name brand, if you feel the need, but I'm not convinced it is worth it.