:check:...Good question mate!... generally, it's better to prevent than cure, right? :brow: Regular supp's of Ca-Mg are fine, just keep in mind mother sources of input; good fert's will have some included, but sometimes it's not enough,... other supplements may have them too, so read labels carefully, and keep account! ...we do see lots of Ca and/or Mg defc.'s here, arguably the most common, even with some folks who are adding extra,...some plants are funny that way, even when there are no other soil/water/pH issues,...:dunno:...and it's no coincidence the two are often paired together! They are critical nutrients, involved in a whole host of roles in the plants' physiology,...***.... many folks note there's a greater than usual demand for Ca-Mg when using LED's,...***... So, follow the label recommendations,...keep account of other input sources and reduce dosage if needed,... size of the plant and therefore demand, is something to account for too,...and that auto's are generally nutrient sensitive,.... to get actual lockout/toxic levels I think you'd have to be pouring brain-dead amounts into your feeds/water! Who does that...? :no: LMAO!!....
*** edit*** forgot to add: Ca and Mg are most often found in carbonate forms,... it's these carbonates that are involved in pH buffering, so having those around is also a plus!...
Would this be a good one , It is what I have .