[AkioVuadan]

Okay, so, I have a 29g with a singe male betta. I've had him for around five months and he's doing great. In his tank, there are live plants, driftwood, a heater, but not a filter. I had a filter when I bought him, but I removed it two months later because the current was irritating him. I siphon the gravel and replace 50% of the water every four weeks. Is that an appropriate amount of time?

 

[christinamac]

It is a good general rule to do a 50% water change once per week no matter the tank size. A 25% water change twice per week is even better. Partial water changes are good for both your plants and your fish. It removes toxic waste buildup and introduces new minerals to the water that the plants use up quickly. Since your tank is large and partial water changes require more work, I would recommend doing a minimum of a 25% partial water change at least once per week.

 

[Warhawk]

With no filter I would do the water changes more often. One fish doesn't make that much ammonia but still 4 weeks is a long time.

I suggest looking for a sponge filter and air pump that way your water is filtered and he will be healthier. I know you said the current was "irritating him" but all my bettas love the current. Mine prefer the current from the hang on back filters.

 

[RussellTheShihTzu]

I strongly urge you to get a filter and cycle your tank:
http://www.bettafish.com/showthread.php?t=555434

I like either of these filters and have used the appropriate sizes in my tanks. I actually run two so I always have a seeded filter if one conks out. If you turn the spray bars to the tank wall it will still allow for current but not impede your Betta's abiity to swim.

http://www.truaqua.com/aquatop-internal-filter-ifs-30.html

http://www.truaqua.com/aquarium-internal-filter-if-204.html

As far as water changes, 50% even on an unfiltered 29 gallon is excessive. Until you get a filter you can do 10% weekly with a thorough gravel vacuum. One Betta is not going to produce enough waste to require more unless you overfeed. I would do weekly water changes to keep the water fresh.

IMO, current is extremely important; no current = stagnant without weekly water changes.