Double grape 9 site RDWC

I'm going to say this grow is probably scrapped. After adding the perfect ph to my grow the ph skyrocketed to over 7. I've added over a pint of ph down and even swapped the water.... twice. Whatever is in the residual water is dping something to super buffer it. Ive received to response from torus hydro for an assistance. I just can't get the ph to stay down. Even getting it below 6.5 temporarily is a serious struggle. I've done dwc for years with many kinds of plantsand have never encountered anything like this. Needless to say I'm quite upset about this.