I did not clean my IC-40 last year...so it has two full seasons w/o a cleaning. Wondering what is the correct concentration of 31.25% Muriatic Acid to clean the calcium of the aluminum plates in my IC-40. And how long should I leave it inside? I have the cap/O-ring which is placed on the outlet side to hold the solution in place. I understand it can be very dangerous to "over-do" it. I assume if I do not see white scale don't he plates, maybe it does not need it.