Ok. You gotta read up on fish in cycle. The ammonia (waste from Fish And food will cycle the tank) but the ammonia level can not got over .50 idea is to keep that level at .25 in order to not kill your fish from ammonia poison. The ammonia will convert to your nitrite( note: nitrite can not get too high either, it is also toxic to fish if it is too high. You never want it dark purple) nitrite will convert to your nitrate. When you get your nitrate reading, the cycle will be complete only when the nitrite and ammonia levels are at zero. But, when you get nitrate and your nitrite is at zero and if you still have ammonia just do a water change to zero that out. No big water changes 50-60% at all times you'll stress your fish out. If you have to do 2 Or 4 water changes back to back , it's better than doing a massive water change at once. I'm worried about your ph level too. Has it always been that low? Could be why your betta is always on the bottom. Test your tap water on ph. What deco do you have in the tank? Rocks, driftwood??? Cycling a tank is work. Specially with fish. Test in morning, test at night. Never miss your water changes, never over feed. Vacuum the bottom for waste build up. Always be careful to not stress fish out. Any questions, please don't hesitate to ask no matter what it is. Everyone on here is happy to help. If you can get good bacteria from anywhere it would help a lot. An old filter cartridge, media, gravel, anything from a cycled tank. So if you know somebody with a tank ask them for some.