The size of the pool has nothing to do with how fast the chlorine drops. I would say (generally speaking) that you'll lose 3ppm of FC a day. But it depends on weather conditions, swimmer load, the amount of organic debris in the pool, how consistent you are about maintaining adequate chlorine levels, etc.. The amount of bleach most people add isn't gonna do much for you cuz most people don't have a 50K gallon pool! I'm guessing you will need to add 2 or 3 gallons of 6% bleach per day. But that is just a guess.

You might want to bump your CYA up to 50 or so. OR -- maybe even higher. Some people deliberately keep their CYA level high because it allows them to go longer between chlorine additions. The downside to it is that if you don't maintain your chemistry and end up with an algae bloom, your shock level is higher and thus it will require more chlorine to clear the pool up. Janet (Aylad) runs a high CYA pool in Louisiana. She keeps her CYA around 80 or so I believe. I'll ask her to pop in here and offer her comments about this as a possibility for you. Not saying you should do this, but just offering it as another option. But, if you do decide to do this, you MUST maintain adequate chlorine levels at all times. Take a look at the Best Guess Chlorine Chart in my signature above to see the correlation between CYA and chlorine levels.