You can’t easily lower the ph in a bagged mix like OF because it is the soil composition itself that regulates ph....well, you can but not using ph up/down. Don’t bother checking runoff that will tell you nothing useful. No need to ph adjust the water you give but you should be mixing whatever nutrients you use at the proper ph range because they are absorbed directly by the root system.
The reason FFOF soil “has nutes only for 3-5 weeks” is because it is a challenge keeping microbial activity at a high level over the long term inside a container. You can add worm castings or other types of compost in solid or tea form which will prolong the viability of any soil mix but unless the soil is actively decomposing organic materials it will slowly become a sterile medium. It is active decomposition that lowers ph; adding active organic materials will lower ph while the minerals in the mix act as a buffer and keep it at the proper range for absorption. So when ppl say the soil is “depleted“ it has in fact just become inactive. It takes years for a mix to become completely devoid of NPK value but you also need an active microherd to consume those nutrients in order for them to become available to the plants root systems through symbiosis with mycorrhizae fungi.
Synthetic nutrients slowly kill off the microbes that decompose organic materials. Big bloom is the only one of the FF trio that is truly organic; the Grow Big and Tiger Bloom are both dissolved salt based chelates. They dry out the bodies of the microbes eventually making your living organic soil into a sterile grow medium. Nothing wrong with that it’s just how it is.
With a clean water source, EWC/aact regimen, and maybe a little fertilizer you can get through an entire grow cycle in FFOF without using synthetic nutrients. The microbes unlock the nutrients in your soil; the plant takes up what it needs through cation exchange. Without them you will need to provide all the nutrients and macros in soluble form so yes that could mean they will need cal/mag, etc if you don’t keep the soil active even though it is contained in your mix. Nutrients sort of force feed them every thing all at once but once you begin using them you must stay on that path.
