Ok, well i think that it is surrgested that you have 3-5w per gallon, and mine will be about 120G, so i think that 2x 300w will do....
Could i use just one 400w?
Hi. Ya they recommend 3-5 watts per gallon, so i would suggest two 300watt heaters placed one at each end. I suppose 400 watts is enough, but i prefer to go a little higher rather than a little lower as my place is cold in the winter. If you can find a 400W heater then you COULD do that if you like, but i think i personally would go for two smaller heaters.
I might see how much they cost, but i think it would probably be worth the money...Do you think that an Eheim 2217 classic external would produce good filtering?
I think i would need about 1.5 turnover, and i think that they are 1000 LPH, so that would be good.