Brown purplish leafs, curling down

Looks like a mag deficiency to me. You need to check your running off PH and also check your PPM.

Hi 👋 It looks like we're mainly seeing it on older leaves yes? Not on the newest upper young growth? I think it looks most like the spots that come from a phosphorus deficiency, the low leaves with the purplish spotting. However you can often have a calcium deficiency come along with the phosphorus and that almost always hit the older leaves or leaf tips directly in the light which is what i see in the pictures... unfortunately as these progress it can bring more and more discoloration and problems, yellowing etc. If you're giving a well rounded diet then you may want to double check your ph. If you gave plain ph'd water the last watering then I'd come in with a low dose of micro/grow/calmag and see if it starts to stop spreading. Usually the affected leaves won't fully recover but you won't see new damage. Fortunately it hasn't gotten so bad yet and you still have a lot of green healthy growth. If you don't always use a calmag supplement maybe make that a more often addition, once a week at least.👍 Happy growing.

Hi its sounds as if you were right with the overwatering if the leaves have been clawing. If she has been overwatered over a long period of time then the leaves will look as if they are developing a deficiency. It may be the overwatering so ease up as you have been, also check your PH as if its to low it may be a calcium deficiency ✌️