DWC - Clean Foam Saggy Plants?

Hey guys got a question, just changed my res in my dwc from trans to bloom phase same level of ec and ppm but my ph is 4.89 and i have a clean chem foam buld up on the inside of my res. and my plants are saggy saggy saggy super soft and flimsy from being a little dry and stiff.

any ideas?

I am on my way to the store to get some ph up right now.

the foaminess is probably from nutes, what is ur ppm did u add to much nutrients maybe? im sorry find someone who knows about ec bro, they can help u lots more im not sure about ec i use parts per million