Is hypo affective, yes. Does it work for every instance, no. Ich are hardy lil buggers that are gradually accepting near fw
conditions these days. 8 months of hypo is extreme and it does look to be ich since Brook or velvet should have wiped them out from the beginning if all you've done is hypo or no-ich. If hypo isn't working you have two choices against ich, either copper (Cupramine) or Chloroquine (expensive but best medication even over hypo). Are you bleaching/net dipping your equipment once submerged in the tank? How are the fish behaving? Are they eating, breathing rapidly, etc?