Am I treating fin rot correctly?

[jimbob]

Housing
What size is your tank? 33 Litres
What temperature is your tank? 26 C
Does your tank have a filter? Yes
Does your tank have an air stone or other type of aeration? From filter.
Is your tank heated? Yes
What tank mates does your betta fish live with? Small Guppy fry

Food
What type of food do you feed your betta fish? Betta Flakes, frozen blood worms
How often do you feed your betta fish? 1x daily

Maintenance
How often do you perform a water change? once weekly
What percentage of the water do you change when you perform a water change? 20%
What type of additives do you add to the water when you perform a water change? API stress coat+

Water Parameters:
Have you tested your water? If so, what are the following parameters?

Ammonia: 0
Nitrite: 0
Nitrate: 5
pH: 7.5
Hardness: not known
Alkalinity:

Symptoms and Treatment
How has your betta fish's appearance changed? Tip of tail frayed
How has your betta fish's behavior changed? Nothing change
When did you start noticing the symptoms? Today
Have you started treating your fish? If so, how? API AQ salt & Tetra medica General Tonic
Does your fish have any history of being ill? not known, Only a week of owning him
How old is your fish (approximately)? not known

After a week of having my betta, I noticed his long tail fin starting to fray at the top and a bit of black gank on it.
Immediately I though fin rot.

Ive dosed with API AQ salt to dose states on packet and dose of tetra medica General tonic.

LFS gave me the tonic free as I have only had him for just about a week and a regular customer.
They use this stuff and recommended it.

Tank is fully cycled, I did a 20% water change before dosing.
He has plants in there but they are silk and did the panty hose test (they did not snag or rip)

[shellieca]

Congrats on your Betta. The best treatment, is plenty of fresh, clean, warm water. 20% weekly probably is not a big enough water change IMO. I would do about 50% weekly or twice weekly. The Tetra Medica is not really needed, if you dose appropriately with the Aq salt (only for 10 days) & make sure he has pristine water his fin will heal up just fine. For the next couple of weeks I would do more frequent water changes.

[FiShFiShFiShFiSh]

I have to agree with sellieca, 20% a week isn't enough, so I'd bump it up to 50%. Aquarium salt is fine, but cleaning the tank more often will work a lot better. Once the fin rot has stopped, you can use some chemicals such as stress coat and bettafix to help speed the healing process. Make sure that you keep his tank perfectly clean until his fins are completely healed, otherwise he could get an infection of sorts. Good luck!