Leaves dying, I am scared that the buds are next (week4 of flowering)

Hey guys,

I have two plants that started out as clones. They are in 3 gallon pots of Fox Farms Ocean Forest soil. Right now they are about 5 weeks into flowering and I am just starting to see baby THC crystals form on the leaves surrounding the buds. The problem is that the leaves slowly start to get orangeish/brown spots on them then progress to the whole leaf turning crumbly and orange/yellow/brown. When it initially started happening I was giving them a half dose of big bloom and tiger bloom. I flushed them with PHed water (6-6.5) and with some CalMag (recommended by the guy at the hydro store). The spreading seemed to have slowed after that. I bumped them back up to half dose and it was fine, then the second half dose watering I gave them it started to get worse. I have attached some pictures of the leaves in various stages. My next step is to flush them again with PHed water but idk if i should do this now or wait a day or two. I have attached pictures of the leaves with various degrees of the issue. Any help, suggestions, or remedies would be much appreciated . Thanks!!!

EDIT: They are under a 400w light that uses an air cooled reflector. and being SCrOGed

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Its too bad our government doesn't allow for studies, and such. I'd flush with silica, personally.