I shiver to think about the money and cost I have wrapped up into my fish,
You gotta love em to get into them.
and such how often should I do a complete water change? and how often should I do a partial change?
I assume this is a 10 gallon tank were talking about right?
If so a complete water change once a yr, maybe longer, depends If you do gravel cleanings with a siphon hose,
Anything 5 gallons and up only need partial water changes once a week of about 20-25%
Only time you need to break down a bigger tank is when a problem arises and it needs a good disinfecting,
Do gravel cleanings and partial water changes once every week.
If you have a tank over stocked then you may very well need to do it more then once a week,
But for a lone betta, Once is sufficient.