White Widow Auto Outdoor

Just starting day 15, week 3 of flower tomorrow actually. I couldn't wait to post the update so I did it tonight. Incredible heat wave hitting temps of 37C but the Widows are flowering very well in my opinion. I only need to water every 2 days but have given nutes on each water. EC was 1.77 and 1.74 with 6l of water given to each. Last water was PH6.4 EC1.32. my runoff this time was pretty much the same from both with PH6.5 and EC of 1.95...which is more than the last runoff of 1.23. They responded perfectly well last water so will see what happens with this one. They are currently getting 3-6-6 for another week or two then will switch to a 0-40-34 to finish. Not sure if this is wise with autos but there is only one way to find out. I'd like to make sure I have two weeks to flush though so hoping for any advice from someone with similar growing conditions and white widow autos? Looking for are to the progress this week!