ya soil mixes are good in that range but soilless mixes should run alot lower 5.4-5.8. there is a big difference in growing between soil and soilless. you could probably get away with low 6's with a soilless but roots do their job better in the mid to upper 5's. Thats why I supplied both ranges for soil and soilless mixes. Also of course everyone has their preference for their specific strains but the ones I provided are a good baseline starting point. Adjustments can be made as needed. Just wanted to give him safe numbers to start with depending on what type of medium he was using.