I am currently treating a fish with Meth Blue and Jungle Fungus Clear. The Fungus clear requires a 25% water change every 5 days. My question is when I do the 25% change, do I place the appropriate amount of Meth blue back in or do I treat the whole tank. It is a 30 gal tank and I am taking out 8 gallons should I treat with 8 gallons worth of Meth blue or the whole 30? I have just been treating the 8.