Changing Water (noob Question)

[Haeun]

Okay, so here's the deal. I decided I'm going to divide my newly bought 5 gallon tank and put my two bettas in the two sides. Better that each has 2.5 gallon than one having 5 and the other having only 1!

But the trouble now is, how will I change the water in the 5 gallon now?
Previously, with my 1 gallon, I just had 2 water bottles (1 pint each x 2 = 1 quart = 1/4 gallon = 25% change) filled and treated, and let it age for 3-4 days. So of course, I was doing water changes every 3-4 days.

But now with my 5 gallon...
(1) How often should I change the water?
(2) How much of the water should I change? Still 25%?
and most importantly...
(3) Where am I going to keep 1.5-2 gallons of water to treat and let age?!

I've also got a real filter going on in the 5 gallon (whereas the 1 gallon has a dinky disposable type) so I guess the water will be a bit better than in the 1 gallon, but I would think I still need to do a lot of water changes.

Help.

 

[Tolak]

Once the filter is cycled change 25% weekly. There is no need to age water, get a bucket & some dechlorinator. After removing the tank water, fill the bucket with the water needed, within a couple of degrees temperature of the tank. Add the dechlorinator to the bucket of water, then slowly add the bucket of water to the tank.

I change out around 300 gallons weekly, it ages about as long as it takes it to run through 60 feet of hose from the faucet to my tanks.

 

[Haeun]

Once the filter is cycled change 25% weekly. There is no need to age water, get a bucket & some dechlorinator. After removing the tank water, fill the bucket with the water needed, within a couple of degrees temperature of the tank. Add the dechlorinator to the bucket of water, then slowly add the bucket of water to the tank.

But that's the thing. My tank isn't cycled yet, and I don't know if I can wait 3-4 (or even 6) weeks to get it cycled, because
(1) One of my bettas is currently living in the small betta cup it came in from the pet store, until it can get into the 5 gallon tank. Not sure if keeping it in the cup for 3-4 weeks if humane!
(2) I'm moving out to college in a week.
But if it's better ultimately to cycle it, I guess I could try digging out an OLLLD 1gallon goldfish tank I had and keeping it there until it's ready.

Hmm. Could an alternative be that I try going to my LFS and ask them for filter squeezing?

I change out around 300 gallons weekly, it ages about as long as it takes it to run through 60 feet of hose from the faucet to my tanks.