selective ich
 

hey everybody. i've been having a pretty extreme case of ich these past few weeks. i have a 55gal american cichlid grow-out tank. it has a cascade 1000(up to 100 gallons). right now the inhabitants incude 2 jack dempsey's(2in) 1 green terror(3in) 1 texas cichlid(3in) 2 eclipse catfish (2in) 1 common pleco(1.5in) and 1 bulldog pleco(1.5in).
i have been treating the aquarium with Kordon Rid ich+ for about a week and a half. it cleared all of the ich off of my cichlids but all of the catfish and plecos are still covered in ich. the plecos are so bad that i moved them into their own tank and i'll have to put the catfish with them too.
Today i took all of my ornaments out and cleaned them after i treated the water with the ich medicine. to treat the water, i change 30% and then add the medicine.
what is goin on? what should i do to treat the catfish and plecos?!?!?!?