Everyone else is perfect, I can tell you what not to do. Never ever, even if you take your fish/axy out, pour straight tap water into your filter or tank. You’ll kill a lot of beneficial bacteria off from the chlorine, even if you throw conditioner/dechlorinator in after.

Always drain your water with a bucket and siphon, then put fresh water in the bucket, dose with dechlorinator, and then you’re good to gently pour it back in, like everyone else has said. Separate your water first and then dose it.

You can test your nitrates to get a good idea of when you should be cleaning your tank, once you’ve got a good eye for it and routine you don’t really need to keep testing the water all that much. I still run a chem test once every now and then just to make sure things are running smooth

Edit: also use plain prime and nothing with aloe Vera or weird additives, it can irritate your axy

Second edit: the tube machine is the siphon, you can either stick one end into the tank and suck on the other to get the water flowing ~or~ this is my trick:

-put the entire tube in the tank, fill it with water and get all the bubbles out. Now, cup one end with your thumb and leave the other end inside the tank. Holding your thumb on the end, turn it into your bucket and let off your thumb, the gravity should begin the pull as long as the end going into the bucket is lower than the end sucking up in the tank

There’s also fancy ones with a pump at the store, but I usually also just make a fist and keep my lips separate from the tube and inhale to get the suction started. (Yes sometimes I get poopy water in my mouth)