I,ve never grown Ak but,
Ph sounds to be fine but could come up a bit 6.7 to7.2 is ideal but i wouldn,t worry about it it,s a long way off nutrient lock.
Co2 ppm is fine Keep it as close to 1500 as posable as you probably know.
But don,t use the smaller plants as mothers as you will end up with a load of slow and small clones, as the behaviour of clones is identical of that of the mother.
Personaly i would let it ride as some plants just seem to be slow and no matter what you do they are constantly back.

Good luck
Disco....
Tech Reviewed by Tech on . need a personal opinion first off i want to find out what people know from experience who has ever grown ak47 what they keep their ph at and what they keep their ppm at. right now i have small ones(3-4in.) at around 500ppm and 6.1ph...the rest ranging 7''- 1' in between 1000 and 1400ppm dependin on the size of the plant, 6.1-6.3ph.....is this about right in anyones opinion?....and also i got about 4 feet in total vertically to let the plants grow judgin by the distance from the light to the plants, and the size of my Rating: 5