Oh boy, that's going to be really pricey to treat such a large tank.
First and foremost, I would make sure you have correctly ID'd that you are indeed fighting Columnaris or not.
Seachem Kanaplex dosing instructions from Kensfish
"Usual dose is 360 mg/40 L (10gallons). Contains kanamycin sulfate, potassium sulfate DIRECTIONS: Use 1 level measure (180 mg) for every 20L (5 gallons). Measurer included. Repeat every 2 days until symptoms disappear or up to a maximum of 3 doses."
A 5 gram tube = 5000 mg (each 5 g tube treats roughly 140 gallons of water [actual 138.9 gallons])
You would need 7,920 mg to treat 220 gallons of water PER DOSE (need x2 5g tubes).
2 doses = 15,840 mg (need x4 5g tubes).
3 doses = 23,760 mg (need at least x5 5g tubes for a full 3 round course. Might need a 6th depending on filter water volume, but you could lower tank water volume but exact gallon).
REMEMBER TO FACTOR IN FILTRATION WATER VOLUME (whether it be a sump, canister filer or whatever. But I guess actual water volume varies depending on substrate, hardscape taking up water volume space within the tank)
Being an antibiotic and you are dealing with such a nasty disease, I would try going for the complete 3 full (underdosing may be ineffective and in danger of creating "super bugs") doses to liken the chance you successfully killed the disease so it's less likely to survive and develop an immunity to the med (it's already hard to treat as it is!).
I believe Kensfish has the cheapest prices for Kanaplex. I have no idea on other meds containing Kanamycin (ask your pharmaceutical friend or maybe a veterinarian)
Seachem Kanaplex 5 Gram
Seachem Kanaplex 100 Gram
Some extra tips, cooler temp water slows down columnaris progression (keep fish stress in mind, so don't drop too fast or too far). Salt levels above 1 tablespoon per 5 gallons or HIGHER, has been shown to fight off columnaris, so has Methylene Blue dips/swabs.
Just so you know, studies have been shown that using Kanamycin
combined/together with Nitrofurazone (found in API Furan 2), has shown to have a higher success rate in curing Columnaris. But it's is another pricey med, and also Nitrofurazone can be harsher on fish and can harm/kill plants and inverts. Just thought I'd mention though.
Fish Columnaris | Fungus & Saprolegnia | Treatment & Prevention