Male betta fish

Question
Help...had my betta about 8mo now.  I have been changing all his water and cleaning everything at least 1x a wk.  .....have been using  2 gal bowl and 5gal aquarium....cannot tell which he likes best...using heater but no filter.   Have 2 different filters....both seem noisy.   Used real plants but changed to silk due to rotting plants.    Am I driving him crazy with all the changes....ESP total water change?
Do I need a filter?  We just got soft water.     Is it ok to use?   I use water conditioner...betta bowl plus and aquarium salt and just added prophylactic disease liquid.   There is too much different info out there on bettas. No one is on the same page.  My betta, Louie, seems fine.    He is a real friendly little guy!   What am I doing right or wrong?      I love this fish!

Answer
Hello,
Sorry for my slow response. I'm moving so I've been a little busy.

It is a refreshing change of pace to hear from someone who is so well informed and so interested in the well being of their betta!
I bread bettas for a few years a while back and have successfully raised over 600 of them. In doing so, I tried many different methods of caring for them, and I have found they all work, but simple is best.
Bettas are naturally very tough fish, and captive breeding has made them even more so. Bettas are happiest with low stress methods even though they can tolerate more stress than most commonly kept species. Some of the things that can cause minor amounts of stress include current (like from an oversized filter), total water changes, and unnecessary additives. Personally, I would keep him in the 5 gallon tank. The extra room allows for the heater and potential filter to be used without taking up much space. You can then add your plants and leave swimming room. The added volume will also act as a buffer to toxins, for example, if a chemical is accidentally spilled into the aquarium, it will be more dilute and less harmful. Interestingly enough, I have found they do not like tanks greater than 300 gallons. I believe they get scared of the openness. In the 5 gal, the added volume will dilute naturally occurring toxins such as NH3+ and NO2- the same way until the nitrifying bacteria in the system can convert them to the harmless NO3-. Try a partial (perhaps 25%-50%?) once or twice a week rather than the total. This will reduce stress on the fish exponentially.
Bettas can tolerate an incredible range of water chemistry. Aquarium salt and prophylactic disease solutions are designed to be used by people who choose to neglect their fish in comparison to your care routine. I used these once with my first tank and have never again used them because they are simply unnecessary and do nothing but complicate the water chemistry. I can explain the chemistry behind why less present fish keepers use these for you in greater detail if you'd like, but the message you should take is that you probably do not need to use them. Consider trying an airstone-bubbler setup, or even a sponge filter if you're rightly worried about noise and vibration.

The one thing you do not have to do but I recommend is feeding them a varied diet if you're not already doing so. Though expensive, frozen foods like blood worms and brine shrimp are extremely nutritious. If you supplement or change to these, your fish will show better colors and live close to two years longer than those fed only "betta food". Again, this is unnecessary but worth consideration. Enjoy your fish. They are surprisingly intelligent companions. I taught one of my brood stock to fetch a ring and jump through a hoop.

Being that bettas are so well adapted to aquarium life, you will find lots of information about their care. The reality is that all of it works! In the words of Douglas Adams, Don't Panic. In my experience, I have found you can't go wrong with keeping it simple. Let me know if you need me to clarify or elaborate on anything.