HOCl generation can occur when high chlorides concentrations are present in the medium. To avoid this reaction to occur: 1) Use Platinized titanium as anode, 2) Avoid chloride addition to the medium. Trace minerals are not specially relevant due to its low content. Macronutrients (N, P) are the key. Specially, avoid ammonium chloride, you can use other ammonium salts (e.g., ammonium sulphate) or urea (synthetically produced and widely used as fertilizer).