I just typed out like a thousand words, and managed to confuse myself when I read it back, lol. So I'll try again (sorry, I'm half asleep
)The basics are the same regardless of tank size. Where it gets complicated is the fact that you know there will be such a small bioload, and creating a massive overkill biofilter is not really necessary in your particular case. So technically, there would be no problem conditioning your tank to handle a smaller biofilter.
That being said, and this is where it gets complicated, there are reasons to still use a fairly high dosage for your cycle. #1- the smaller the tank, the less stable it is. They are more prone to future biofilter problems simply because of the lack of surface area (where the bacteria grow), there is simply a fewer number of bacterium that live in the aquarium and small changes can make a big difference. For instance, if you had a big 55 gallon tank with 4 filter pads, losing one wouldn't be a big deal because there's so much other surface area in the tank that the reduction of bacteria won't really have an effect. In a small tank, removing a filter could have drastic consequences.
Long story short...sorry I know it's long...I'd vote for the middle ground and dose up to round 2-3ppm. What will likely happen is that once the cycle is complete, there will still be a very strong biofilter in your tank, once you add your fish the bacteria level will adjust based on the ammonia your betta is putting out. Technically, some of the bacteria is dying off, but the correct amount will remain to handle the waste your fish produce.
So to sum up my (rambling) thoughts, it's better to take a little longer and grow too much bacteria, as opposed to dosing it too low and not having enough to handle what your fish can produce. Better safe than sorry.
I hope this makes any sense, lol. It's past 2am and the bed is calling my name
. So Id keep it up around minimum 2ppm for now, and I'll check back soon. Feel free to PM me with any questions, because I'll only be checking the actual threads about once a day. Good night!