My first coco grow, once a week I would mix my nutrients up, and at the start I was phing the big container that was holding my premixed nutrients. Was hand watering, so not a real reservoir, just enough nutes to make it through the week. I started off phing that container directly, and it didn't matter cause a day later the pH had climbed back up. I ended up measuring out just the amount of water I was feeding the plants that day, and ph'ed that directly. It meant more work during the week, but I think it worth it in the end. If you are using your reservoir to directly feed the plants, that idea won't work.
You may not vote on any more threads today.
Don't sweat the technique.
And honestly. My fuck ups turn to gold so much the thought of fuckin up don't even bother me. So I keep it auto when I'm stepping through a portal. I know that sounds strange but, strange beats normal.