How long can my fish go w.o filtration?

Hey all... got a separate post about the disease destroying my tank currently but today I took action... got a 75 gal tank that was fully stocked and the last fish in brought a bacterial infection (seems to be columnaris) with them. (I know QT, was full and this LFS has always had really good fish). So anyway so far its killed 2 corries, 2 emporer tetras, 1 platy, and 1 balloon belly molly. What a wierd selection of fish to kill considering I have other more fragile fish... anyways I bough the required medication but its expensive ($20 for a 24 pack) but to treat my sized aquarium I would need actually 48 of them so I came up with a better plan. I drained my aquarium to 50/75 gallons and am treating that way as I can get away with only buying another 8 pack for $8 or so rather than the $20. I have 3 bubblers running (in addition to UGF but idk if those are actually working since water doesnt reach the top of the tube). The filter absolutely will not work in the current state the tube is just barely under water. Can my fish go the 5 days w/o filtration? (note I cant do water changes either because it will mess up the dosage). Basically w/o this treatment everything in there will die as it apparently is a very fast moving disease... one fish was fine yesterday didnt eat this morning dead on the bottom tonight when I got home. Please advise to the filter situation Nothing about this is good but im trying to do the best I can...

In addition to the medication Maracyn-Two I also turned off my heater to bring the tank temp to around 75 as this thrives on warmer water... also last night I dosed the tank w/ salt for the full 75 gallons and after lowering to 50 added 5 more tablespoons (1 spoon= 5 gallons) because I read that the disease wont survive the salt and most of my fish will tolerate it just fine.

I know I should have just waited but I didnt know when I would be getting rid of the goldfish in the QT... I just hope it doesnt get my L144 I really like him

Yea the filter needs to be cleaned very well before re-use. Will let the filter media dry out and use the newer pieces again and replace the old pieces that likely harbor alot more but being dry should kill everything. I wont start everything over unless it kills everything as I like alot of my fish and many arnt found locally so the only replacements would be shipped to me for an even greater cost

Also will it help me to not feed the fish for a few days? If I dont feed they wont excrete as much right? And I know fish can go days w/o eating with no problems... I was thinking probably id feed on the 3rd day (fed them today) of the medication and then feed on the 5th day after I add back 25gals of water and restart my filters.