What's the point of soaking food when the fish is not eating?
I use 500mg metro and dose 1 tab/40ltrs water after nearly complete waterchange.
Redose daily after 80% waterchange for 7-10 days.
Crushed the tab using a mortar and pastel into paste. Add water and grind. Tip into tank.
Increase temp to 31 deg with and airstone in the tank. Don't need filter.
hth,
Ron