Well there are varying amounts of water changes depending on the member in here and what they believe... AND how OCD or lazy you are. Most will suggest 30%-50% weekly as your fish are living in their own pee. Ooops sorry is that a surprise? Well it's true.
Fresh clean water is the best medicine and a good routine of weekly water changes will keep control of excessive amounts of Ammonia, NitrIte and NitrAte. More to follow on these once you setting up. Have you read the articles on Cycling a new tank?
So... anyway... I am one of the lazy ones... ehhhemmmm. So I do about 25%-30% every 2 weeks. Yes I know it should be more but I also have a turtle that needs them almost 2 x a week so I have that darn hose laying about all the time.
Water changes will require a thermometer for sure. Get the floaty kind, they bob about the tank, or you can put it into one of the filter chambers. You will need a separate bucket just for your fish, never to be used for anything else... ever, ever, never, never. I have a juice jug, marg container, cups and tubs, a couple of scrubby pads, pair of scissors, a turkey baster, set of measuring spoons, and small pocket calender.... kept all in a big tote (or cupboard in the stand under the tank) If you ever get another tank (he,he,he... !) you have a full set of these for each tank. No cross contaminating!! (get as much as you can out of your kitchen cupboards or the Dollar store!!)
(Wait till she walks past the Bettas at the local fish store (LFS) and he wiggles his little fins Hello at her!)
When you are at the LFS this week, look to see if they have made things simple for you by putting red, green, yellow stickers on the tanks. Green is Community fish, Yellow is caution, and Red is doesn't play well with others!! (one species only tank).
Sorry back to water changes.... Starting out, you would open the lid, use one of your marg tubs, scoop water into the bucket and take it to a sink and pour it out. When you have removed 1/3 you check the water temp in the tank, go run the water in the sink that you can get your bucket under the faucet, and using as close as possible, within 2 degrees max, treat the water with de-chlor and take the full bucket back to the tank and pour directly in, or scoop the new water back in with the tub. When you are fully tired of that method.... next Christmas you will be asking for a "python" style hose that you connect directly to the faucet which uses siphoning to pull out the old water, close the shut off valve, put the de-chlor directly into the tank, set the temp at the sink, reverse flow..... open the valve and fill the tank. DO NOT go too far from the tank at this point... do not answer the door, go do laundry, go for a nap... etc. lol or you will have a rather wet floor! Ya I've done it!! Shut off the valve when full, run back to the sink and shut off the water. Does that give you a visual of the 2 processes?
(by the way, you are almost at 15 posts which will get you any time into the Chat room to speak live with other members when they are in there! You can see if someone is in there down at the bottom of the main menu, it lists the names of those chatting at that moment). Come visit us some time.