Your ppm # for white widows?

 
Mine max out at about 600-650 but it will vary between set ups. After about 4 weeks in to 12/12 you will start to see a drop in ppm that the plants take up. This will carry on dropping until...... Well, for me it's about 200. 
 
When it reaches this figure ill replace the nutrient solution with empty water
 
That's on the condition that they are about a couple of weeks from finishing. But this usually coincides pretty well

 

I grew 1 white widow auto recently, it was a heavy feeder I hit it with GH Floranova Grow & Bloom at veg & flower respectively, as well as CalMg during veg. It continued to have ppm drops between feedings (meaning its eating more than drinking, according to GG's great feeding tutorial) all the way through 1400ppm (0.5 scale) until flush. I switched to ro water after trichomes switched to mostly cloudy some amber.

 

 
Those figures are very interesting to me. Do you have a journal of that grow? Did you defoliate at all? 

 

Yessir its in my sig, I stopped tracking the ppms on the forum about halfway thru but I kept track on a hard copy.
Hm nope don't recall doing any defoliation aside from a few fan leaves here and there that started to lose color then wither, they came off real easy couldn't have been more than a handful.

 

My last two crops had white widow as one of the strains Involved.
I maxed out at around 900 ppm by week six / seven of flower
I determine nute strength by PH variations and PPM levels as the res levels drop. If they both stay stable I don't increase strength. If PH and ppms increase as the level drops its too hot and I'll add water to lower it

I flush when I see roughly thirty percent amber trichs and I flush with roughly 200 to 300 ppm nute levels for a week minimum

 

I'm growing some widow right now and she takes 1300 ppm with no problems. Week 4 of veg. On floraduo feeding schedule. They do feed.