hi all ,im asking yall for a bit of help here... one of my aquariums ,a 70 gallon,with an aqua clear filter,diy window planter bio filter with bio balls and filter floss,an internal canister filter connected to an air supply.,,has recently been attacked.. fish started showing signs of ich,which was treated with the thermostat (up to 28 degrees celsius)and salt,after a week i used a metyhlene blue solution as i saw the fish had developed wat seemed to be velvet,cramped fins,red spots,the fish wer hiding behind filters etc...i have lost 2 out of 6,i have two red caps left which seem fine? healthy eating active etc and i have a baby lion head which doesnt seem good.... (they 5cm in a 4ft 70 gallon) wat i wanted to ask is.. (my parameters are good) ive thought about treating the entire tank with a general fungi,ich finrot medicine,to ensure ive rid this tank of all diseases should i use a hospital tank and treat the remaining water as is? or should i scrub down the tank,do a complete water change,leave the filters as is, (uncleaned),use a water primer ,add the medicine and let it run into all the filters? ive heard the medicines,tetra med suggest not running filters at this time but my question i should i try to ensure nothing can hide? so complete water change add meds and run filters? or leave water as is ,medicate,and just air? or hot water, clean out leave tank to dry in the sun,but my question here is wat about the filters how do i ensure the healthy bacteria stays without the risk of these diseases hiding and re infecting the tank? so without sounding too repetitive.. cleaning the quarium out with hot water ,scrubbing it down and leaving to dry should kill anything left in the tank itself, but how do i rid the filters of any of these evil sob's whilst keeping the bios healthy and ready to start cycling the tank once again.. much appreciated.