You can cut off the dead leaves or even part of a dead leaf. They will not get better or grow back. You can only tell from new growth and how it acts if you have corrected the problem. Some of the older leaves may still turn only because of the time it takes for dirt grows to improve. Stick with Ph adjusted RO water for a few more rounds. Once you do start to use nutrients use only 1/2 strength. You still have some residue of that MG in the plant you need to leach out. I have no experience with that bloom formula but I would lean more to the cactus formula for a resin producing plant more then a flowering plant for nutrients if that is your only company you can get.