6 is fine. give yourself a bit of leeway that way... anything below 5.8 is going to lock stuff out. maybe, okay for clones and seedlings, but a real plant not so much.
hopefully, you have ph-buffered nutes. that'll make it much easier and no additional ph-balancing is needed. this is a trait of high quality soilless/hydro nutrient products. those that don't do it are just lazy manufacturers.
realize that fertilizer ingredients are ubiquitous commodities. do not overpay for such common things. there is no higher quality MKP, for example. it's all the same MKP. There is no high quality calcium nitriate, it is simply 100% calcium nitrate no matter what brandis on the bag. read the ingredients. see that htese thigns should not come with a premium price.
i pay 4 cents per gallon mixed. that includes the water used. a lot of these brands are 15-20cents per gallon or even much more. insanity.