I have several spots that need patching on my 26 year old IG plaster pool. How do you do this? Do I have to drain to patch? My CH and CYA are sky high so I will need to do some draining anyway. My thinking is to wait until the fall when the sun is weaker since I read direct sun could damage exposed plaster. Is it true? I don't want to have to fight the chemicals and high chlorine for the next 3 or 4 months. What' the berst way to do this?