How big is your rez?
---The amount of hydrogen peroxide is dependent on rez size
How long ago & for how many days was rez temp high?
I have some personal issues with Dutch Master but I know several local growers who swear by them.
I'm pretty sure though you don't need to add cal/mag with the Gold series unless the plants are asking for it.
So you might have TOO much cal/mag (I know it sounds crazy but it happens).
Like I pm'ed you, flush & change your rez, add minimal nutes but just the Dutch Master for now, and add some hydrogen peroxide.