Help with some lower leaves

This is my first grow. I'm doing auto ak47. I'm 6 weeks in and have just noticed some of the lower leaves are dying and falling off and some others are going rusty and other are withering yellow and dying within a few hours. It's not a lot so far it's been about 6/7 leaves in 48 hours. Here's some pics







Any ideas on what I'm doing wrong. I've been giving them canna terra Flores nutes for 3 weeks been increasing amount every other feed. I'm on full strength now. They are in John innes #3 compost and I'm on an every other day watering schedule. I've been increasing the amount of water gradually. They are having 800ml each every other day. May increase to 1 ltr each next time

compost is alkaline........what's your ph? watering e/o day sounds like a lot of water. cannabis roots need to dry out.

I'm quite limited to what I use to test ph. I'm using a urine testing kit. Ph comes up at 6. I am only watering so much because the soil feels dry and the pots feel lighter.