This is what is meant to happen.
Feed goes in, less comes out.
PH from run-off from feeds etc. You really should look to see what you're seeing.
Its weekly flushes of just water. You will use the pots value of water for a hard flush to flush of salts and that.
I'm not an expert on coco, I've only used it once. But, you shouldn't be seeing large run off in every feed.
Its a weekly process, or a fix if overfed etc
Also you're using way to many nutes.
Big bud: good.
But you don't need sugars, bud enhancers until there is actual bud.
Big bud is a stim used for the 1st 2 weeks in pre fower. Then you start adding the sugars etc..
There are many guides.
She is looking super tight though. Don't stress it too