New growth brown, thinning leaves

A question from a fellow grower:

would you be able to tell what is causing my plants to burn on ends, but new growth is turning brown and leaves are thinning

Ppm is now 900 and ph is now around 6. When I first noticed problem ph was 8 temp is around 80 degrees f in a DWC system

Yeah your ph swung way out of range to fast , but you are in flower stage right ? I’ll balance ph to about 6- 6.2 , ppm about 1100 and don’t let ph swing out to fast and it should be fine .