You can live with 80 ppm, but need to keep the Free Chlorine (FC) level at 6 ppm or higher for a manually dosed pool. Some people in hot sunny climates keep their CYA levels this high and many saltwater chlorine generator pools do this as well so its certainly manageable. The main downside is that IF you end up getting algae or unusually high chlorine demand (i.e. nascent algae bloom), then the shock level is very high so would take a lot of chlorine. So long as you manage your pool properly, you should be OK. Your chlorine loss rate will be lower at this high CYA level -- probably around 1.2-1.5 ppm FC so you could start at 8 ppm and end up above 6 ppm each day, for example (assuming you are adding chlorine every day). I'm assuming your pool is open to sunlight -- if you have a pool cover, the chlorine loss would be lower.