Several problems
A very small tank of that size should be changed at least 30% twice a week.
The Charcole is taking out anhy medications you are using. If you must use it only use it with out any medications. Also it only lasts about one month before it can become a problem.
I would get a full water test done as I think it sounds like a water polution problem.

Keith

I change the filter out entirely every 30 days.

I haven't been medicating at all, so the charcoal hasn't been a problem in that regard. Once I figure out what to use for this, I'll remove the charcoal.

Unfortunately, the only pet store in my area worth a damn hasn't reopened since Katrina, but I'll try taking a water sample to PetCo.

Would a pink or red ouchy spot be caused by high levels of ammonia, nitrate, nitrite, or ?? Diagnostic websites (text only, alas) seemed to hint at a fungal infection. Water quality issues typically manifest as behavioral changes, no?

Hmmm...

Poor water quality of any sort can result in many types of adverse reactions - whether physiological or behavioral.

You need to up your water changes. Smaller tanks tend to be less stable overall.

Ok, I'll increase my water changes. 30-50% per week, or twice per week?

The spot has reduced in size; it's no longer a puffy spot, but rather a dark red colored spot (matches his belly fins), and he's swimming freely and not clamping his fin down anymore.

Is it possible that this was merely an injury? How quick do fish heal?

You filter would be very small for a tank that size and I would clean it out twice a week using the removed water by doing this you will not kill all/any of the good bacteria.
Why are you using the charcole as it can be more problems than what it is worth. It does have its uses partically after using medications to clean out the tank, after that it is completly tosed out.

Since I started up my 11G Betta tank even with all my 35+ years experience I still find it the hardest tank I have ever had to maintain correctly. With big tanks 5ft+ there is always room for any problems but with a small tank 30g- there is very little roon for error and once you get to 10g- there is no room at all for any errors at all.

Keith

[b][I]Look here for my
[link=Betta 11Gal Desktop & Placidity 5ft Community Tank Photos]http://photobucket.com/albums/b209/keithgh/Betta%20desktop%20tank/[/link]

Sorry looks like links dont work here.
http://photobucket.com/albums/b209/keithgh/Betta%20desktop%20tank/
Keith

When you say you change out the filter entirely, do you mean just the mechanical filter and the carbon, or do you also remove the bio-filter? Assuming you leave the bacteria alone and your tank is cycled, 30% once per week is good for your tank. I keep a betta that way, and test the water to be sure. He's very happy and healthy. I have another in a tank that doesn't even have a filter that cycled itself, and I maintain it the same way, also with low nitrates and a happy fish.

It sounds like it could be an injury, especially if it's healing already. How long have you had him? What kind of decor do you have? If he's new or you recently added something, look for a possible cause (plastic plants can be dangerous) and remove it. Another possible cause, assuming he's new, is the filter current. Is the output very strong? Their long, flowing fins are suited to a currentless rice field. You can use a suction cup soap dish, plastic canvas, and plants to diffuse the current for him if you need to.

A red bump, though, doesn't quite sound like a normal injury. Usually fins just rip, from what I've seen. There are many parasites and illnesses I don't know about. Could you possibly take a picture? Even if he's getting better now by himself, it'd still be good to find out what he had for future reference, yours and mine both. :)

On another note, is the spring water pure? It sounds like it must not be if you're getting a hard water reading, but I don't know too much about bottled water. I do know, though, that most of it is devoid of minerals and things you find in tap water, which is why treated tap water is best to use. But like I said, I don't know too much about bottle water. I think spring water is supposed to have fancy minerals in it though... Just something I thought I'd mention in case you didn't know, but it sounds like you know what you're doing. :) Oh, and he should be fine with hard water so long as it isn't too hard.

Also, kudos on not giving him a random medication. So many people do that, and it just hurts more than helps.