Flood and drain in rock wool flush

So I’m at week 4 of flower growing in 4 in rock wool cubes. Changed res 2 days ago and look in the tent and leaves are clawing. Ppm is 1150 ph 5.8. Running jacks with a bit of fox farms beastie blooms maybe half strength. Any thoughts?

What scale is your meter? 500? 700?

Got a cheap one from local hydro store so I’m not exactly sure. A buddy and I are going to build me a current culture system and my next is the auto dosing deal. Cost like 600 I think but well worth it.