Rubert in my system it is bufferd to a high ph range because of the gravel media. Does it make sense to add the Potassium and phosphorus to help with fruiting or am i wasting my time because of the high ph. ph range is 7.6 to 7.4

RupertofOZ said:

That's true TCL... and similarly with phosphorus... but remove the Calcium buffer... the carbonate...which is responsible for the "over-abundance" of the Calcium in the first place... and pH will drop... and the Potassium uptake will probably occur even if a large amount of Calcium is still available...

Do you use seaweed extract David?  My big system has run a pH in that range for years and I still get fruiting on my tomatoes, bananas, eggplant and yardlong beans.

Funny how this discussion slid off timed flow to towers....hehe.  Nutrients seem to be far more interesting.  On that topic I have been mulling a question for Rupert: With your knowledge of AP systems and crops, you have recommended a hydroponic literature source to me in this thread.  In the older stuff I have (Savidov, UVI) there were often statements made to the effect that "AP does not operate like hydroponics" and that the nutrient availability and use patterns are completely different.  Is this being contradicted by the Aussie experience with media bed systems?  Can one safely assume that meeting a plants needs described in hydroponics would be exactly the same in aquaponics?