Hi all.
Does anyone know if I need to flush/wash plagron Coco before use with pH water?

I'm asking as I have recently put my 10 days old plants in my Wilma system and no matter what I do after the water/feed has gone through the pots the pH in the tank has risen from 5.8 to 6.4 I mean almost instantly from a 15 minute feed.

Also the water in the Res has turned a pinky brown colour.

Using plagron coco, ionic nutrients. And lots of pH down.

Really starting to piss me off to the point of going back to soil.

Thanks for any advice.