Flora Nova will lower you waters ph 6.0 out of the optimum range unless its intended for Hydro .. Your going to want to use a meter when feeding as well as ph up .. Your soil looks peat based and if its aged the pH will be lower than it once was .. All soils have a Ph buffer . Most use lime but some use oyster shell .. I have a soil pH meter of high grade quality and we could find out what the root zone pH is and that helps more than anything in a sense when keeping things optimal .. Let me know bro and I ll bring it over soon ..
With soil you want to maintain a ph of 6.5-6.8 Soiless 6.2-6.5
Edit : I thought that was ProMix based lol