deficiency in final stages of flowering, what action to take?

Hi rollitup community,
Just noticed a problem with a couple of my northern light autoflowers. They are just over 2 months old and look like they need chopping in about two weeks. I've noticed little rust spots on the top leaves which I'm pretty sure is a calcium deficiency. I think it's because the ph of the soil is too low because they've definitely had enough calcium, although I can't confirm this til I receive my new soil ph tester (old one was a deceptive piece of shit). Anyway, if it is low and given that I only have 2-3weeks tops until harvest, what can I actually do to help the plants in short time? I've researched methods of raising ph which all seem to be slow processes so is it even worth trying to solve the problem at such a late stage ?? Appreciate any advice

Definitely worth trying! Even if you only raise the ph by a few decimals it might mean a few more grams of weed at the end of the day. You probably won't "solve" the problem by harvest time but if you alleviate the stress, even just a little, I'm sure ur gals will reward u for it.

if its not affecting the buds just roll with it you must be coming up on the 80 day mark they always look shitty about that time and it breaks your heart to see them when its harvest time if you dont touch any of the fans and leave the shrivled remains of fans just hanging there when they are trimmed they look like a million bucks i mean you cut the fans off any way so it is what it is
the rust spots are probably a cal mag def for which at this point there is really no cure anything to do with cal mag that isnt foliar is pretty slow acting if its a ph lock out like you said its all fairly slow acting