Fins not healing after fin rot

[alli789]

My betta has moderate fin rot that doesn't seem to be healing. I haven't noticed it getting worse since I started treating with aquarium salt, but his fins don't seem to be growing in. He has a large piece of fin missing that doesn't appear to have any growth at all. There's a smaller area of tattered fin that has a tiny bit of what looks like clear fin growth, but it hasn't really changed for a week or more. I'm guessing since it's not getting worse the bad bacteria are probably gone, but how can I get his fins to grow back?

I treated him for one week with the 1 tablespoon per 5 gallons salt dose, then doubled that for the second week. Tomorrow marks two weeks of salt treatment, so I was planning to start Colin's recommended daily small water changes to start slowly removing the salt.
I've also been using stress coat to try to encourage fin growth.
One thing I did do was drop the water level slightly so that the oxygen exchange from my HOB filter is better while there's salt in the water. This definitely increased the flow strength a bit, but my betta has been steering clear of the flow. It's not too strong, but I'm sure it's a little stronger than it is when the water is topped off. I don't know if this could contribute to his fins not growing in?

He seems totally fine other than the fins not growing back. He has a great appetite and is active.

Tank stats and parameters:
10 gallons
Heated 80 degrees
Fully cycled
HOB filter with intake sponge and thick interior sponges to slow flow

Ammonia: 0
Nitrite: 0
Nitrate: 10-20 (due to change water tomorrow. Probably are closer to 20 due to high tap nitrates that I dilute with distilled water.)

 

[JxsPxxle]

I suggest cleaning the gravel thoroughly with a gravel vacuum, and doing small daily water changes.

 

[Fishiemang]

If the water is kept.clean, they will grow back. It takes a long time.to get back to flowing. Months. Depends ona.lot of variables....

 

[Colin_T]

Any pictures of the fish?

As mentioned by the others, assuming there is no bacteria or fungus keeping the wounds open, the fins should grow back in a month or so, depending on how badly damaged they are.

Keep the tank clean with regular water changes and gravel cleaning, wipe the inside of the glass down regularly, clean the filter regularly to help the fish recover.

Feed the fish a variety of food 3-5 times a day for a month to help build it up physically and provide it with more nutrition to help repair the damage. Make sure you do lots of water changes and gravel cleaning when feeding more to keep the tank clean.