I’m using the FloraDuo Recirculating Expert Plan, which you can find here: http://gh.growgh.com/docs/Feedcharts/GH_FloraDuo-REC_03216am.pdf.
This is typically the concentration I mix for my 2nd stage of feeding. All the same nutrients are used for my first feeding, however I do those at a 1/4 strength, which gets it up to about 400 ppms. This feeding is 1/2 strength at about 800 ppms.
Disclaimer: I grow marijuana legally according to the state law in Massachusetts (and still get elated every single time I say that 😀). Make sure you follow the laws wherever you are.