Also, if you can add a UV made for Aquariums (TMC Vecton are brilliant) then it will kill the larval stage of the cycle and stop it happening again.
I have had Puffers and Clown Loaches in the past for many years and not once had an outbreak and both of those fish are the "kings" of ICH.
I run 2 500litre UVS on my tank - as does T1 and change the tubes regularly. T1 recently let me know that the arcadia tubes last 1 yr.
You need to be careful with treatments and flow the water at the correct rate....too fast and they will not work.
Hope this helps