Did another 50% water change today, I did one two days ago so that I can start new treatment asap and to get the melafix out of the water, although the lfs said melafix is fine to use with this medication The internal bacteria is two step treatment so ive dosed water today day 1 and then I have to do on 4th which is sunday, I will do a large water change again in 7days on Tuesday and test the water sat before 2nd dose, just incase I need to do a part waterchange before second dose, it says that the treatment doesn't affect the good bacteria or filters but you never know with medication. I do have 3 filters running on the tank, one external ehiem 350 classic with a large body of media (no carbon sponges) and two internal filter pf2 interpret and a ehiem 2012 pick up. Il keep you updated on Ludos progress