Water Changes for an Unfiltered 2.5gal?

[MadameDesu]

So, this is my basic tank setup: a large Kritter Keeper that holds 2.5+ gal of water, a Tetra Whisper3i Filter, and a Cascade 7-watt heater. I didnt cycle it before I got my fishy :X
I've had my betta for about 6 months now, and she's been doing well with weekly 100% water changes.
Recently, I've heard that this is too much water to be changing every week. Is that true? If so, how and when should I do partial water changes?
Also, is there any chance of a cycle establishing itself if O never change the filter media or kill the bacteria in the gravel?

[aokashi]

If you've never changed the filter, theres a good chance that there is a cycle :) no matter how unstable.

I would say keep up with the 100% changes if your fish is happy. if you're worried about the fish, I used to change my baby bettas water every half a day. he survived beautifully, lol

[MadameDesu]

I actually have changed my filter recently /)_-
What happened was I tried to put a sponge media into it, but that totally sucked and the water got gross and my fish got fin rot/bit her tail, which she's being treated for now. I immediately took out the sponge and put a new filter in. So I'm basically stuck waiting for another cycle to establish itself from whatever bacteria is left in the substrate.

[BettaQi]

Oh how sad!

I am researching Seachem Matrix filter material now, before I buy the filters for my 5 and 2.5

I change my girls' water 25% -50% daily half in the morning half at night.

Sometimes they poop more than others!

[MadameDesu]

Yeah, I'll probably be sticking to not changing the filter. I wanted a sponge to get better biological filtration, but I bought the wrong size and it didn't clear out any particles or gunk, so it was a bust.
I'll probably save the sponge filter for when I upgrade to a 5 gal.

[babystarz]

Right now I'm doing a 30% water change every other day on my 3 gallon. It has 4 small plants in it as well so I don't want to take too much water out at once and flood in the new stuff.

I also have a 2 gallon, unfiltered tank getting 50% water changes every other day, it has no plants.