According to Projar Product Manager, Paco López and expert in Hortofruticultura from Valencia (Spain): We are offering crush chips extra washed, it means E.C ≤ 1.5 mS/cm (Sonnelved method 1.1.5 v/v).
Even that this E.C is suitable for most of crops, the point is that coco coir naturally contains in its exchange positions Na+ and K+ (linked to negative positions, they are not possible to remove only washing with water), they can unbalance our nutrient solution during first plant stages or even be toxic for certain crops as berries; it means that all the calcium and magnesium that we add as fertilizers, coco it is going to hold them on it is exchange negative positions and release sodium Na and potassium K; so to avoid problems during these stages we need to buffer the coir fiber. To Buffer the coir fiber we must introduce divalent Ca+2 and Mg+2 ions
to remove natural K+ and Na+ ions present in coir fiber.
We recommend to buffer coco when we are working on 100% coco coir, but you are working on a mix of compost, peat moss and perlite; compost and peat moss will minimize the possible toxic effect of Na excess,
also you are growing not very sensible crops as tomato or even cucumber (it is more sensible but we are not talking as if it will be a strawberry).
We are a substrate company, and we never have toxicity problems mixing washed coco (not buffer) with peat moss and other substrates.
On a non-organic crop, using water soluble fertilizers we recommend this solution to buffer coco while expanding it: Mix 1 Kg Calcium Nitrate (CaNO3) + 0,3 Kg Magnesium Sulphate (MgSO4) or Magnesium Nitrate (MgNO3) per 1000 Liters irrigation water.