10%? I would without doubt up this to 30% weekly at a minimum, more IMO
. Changing 3gallons of 30g is nowhere near enough. Besides the fact 30 gallons isnt big enough for africans of any kind except dwarf mbuna or shell dwellers and the fact its a tall makes it worse. Peacocks need a 4ft long tank, theyre open water swimmers and i imagine yours is only 2.5ft max. It doesnt make much difference that you only have a few fish, there still isnt enough room to stretch their fins without hitting glass.
Cloudy eyes are caused by bad water quality, alot of stress or nutritional deficiency. I whole heartedly recommend changing Much more water. It will usually clear up by itself aslong as the cause is addressed and if it doesnt treatment will be needed or your fish will become blind. In your case and based on your first post i have to put it down to water quality.