light brown spots on bottom leaves. is this lack of calcium or maybe its normal?

So it doesn't look bad yet...but it definitely looks like a calcium deficiency in the making. With growing soiless i know the ph needs to be lower, but calcium usually absorbs best closest to 6.2, you can probably get away with the 6 but maybe need some additional calmag supplements. coco coir always needs higher calmag doses i wonder if that applies to all soiless mediums...the peat/perilite combo. I'd try boosting it up a bit, even just 1 dose a week and see if it spreads anymore.