If its not too late, I would order the double, if you have room... It's a small price difference and will make it much easier for you in the future. For example, if you do want to run more than 1 media, say GFO
and carbon, it is a pain to run them both in one cylinder, and if you need to change one, it will be very messy/near impossible... Carbon, for example, will run with results for 2-3 weeks, but GFO
will run for longer. So if you have a dual, you would only have to change out 1, instead of needing to attempt to remove 1 of the media.