EC Rising, PH static, Water level dropping. Already tried the solution from the popular chart out there and same thing. Drinking EVERYTHING but EC shoot up

i did a full res change which the chart everyone uses for these kinds of fluctuations in hydro suggested. The verdict was full res change possible acid rain effect. So i did a full res change. Getting the ec down from 2.2 ish to 1.6 which is stable for RDWC. but it drank damn near all the water already (2-3 days) and the ec is back at 2.2-2.4 ph 5.7 and im using a 27 gallon res outside the tent with a chiller set to 68 def F No the water level is dropping like CRAZY, they are drinking and drinking roots look great, and the plants look great. I calibrate the ph meter bi-weekly or at most monthly. I use a Bluelab guardian. can I even calibrate EC on that?? DAY TIME H/L AVERAGES: TEMP: 86 / 75 deg F RH: 60.5% / 40.6% NIGHT: TEMP: 72.8 low / 78.6 max deg F RH- 49.7% / 57.7% Two things to note: I have a combo AC / DEHUEY that worked fine last grow but entered itself into this mode that threw it off my schedule my last temp/rh was perfect but i just caught and fixed it. second, I have a small dehuey im putting back in today, it only intakes 2 cups per day or 8oz. night time temps running around

So you are lowering your feeding solutions EC from 2.2 to 1.6 and it keeps jumping back up to 2.2 or above? without any changes to PH or water level? I would say if the water level is lowering and EC is going up it then just need more water but this is something different. How are the roots? do they have a off smell or texture? when the last time you calibrated/cleaned your EC/PH pen? Is your RH and Temps in check? curious if the RH is low. Hopefully a hydro head will chime in as I have yet to grow in RDWC. Good Luck!