I mix in 1 gal containers as per GH mix a day ahead of water change outs. Adjusting amount to 800 for flowering.
I use GH's PH adjustment.
Had sign's of leaf burn when using recommend amount, ppm was in 1100 range, had read in other a post that ppm should be around 800.
The only change was a new supply of GH 3 part Flora Nut's.
I us rain water and use a DIY filter before use, and the water only set for a day or too at the most. The PH most of the time is around 6.5 - 7.0, in the string it does drop to around 5.0 - 4.5. The PPM is 12 - 35. all the time.