I think I should have paid more attention in science class now? Ok here is what I have read. A high PH can block most other things like magnesium and iron. And potassium. A high carbonate level will prevent your PH from going up and down to quick? So if you have a high PH now. Then you may not need to add anything? As the high PH could be blocking the potassium and iron from your plants?
Building a system is easy. Getting the plants to cooperate is the hard part.