1. 2-3 weeks / preflower is a good time to start feeds
2. if theyre thirsty they go limp/droopy
if leaves are tight/springy and curled down its over watered
the plant talks to you is how you can tell its hungry yellowing leaves ,spots, this is something that you really have to learn for yourself find some good nutrient deficiency charts and figure out what nutrients are needed when
3. ph ? anywhere between 6 and 7 shoot for 6.5 ( ph to 5.5 in hydro) 6.5 in veg and 6.8 in flower if i remember correctly dont quote me
but im positive most people shoot for right around 6.5
4. if you're feeding small doses or like kelp or calmag , or organics you can feed bland doses with every water
be cautious of salt build ups though
i usually give a mini flush or two if i have been feeding heavy
doesnt kill the plant if it dries out soon enough , but is hard on the soil and leeches all the goodies out
5. 1 cubic foot of soil is is over 5 gals of soil according to this
http://www.metric-conversions.org/volume/cubic-feet-to-us-liquid-gallons.htm?val=1 12''x12''x12'' is a cubic foot right ? stoned
6. if your going soil there isnt much need for a ppm reader
but its your grow bud
ebay has a good selection
but i think HTG has a good one just remember you get what you pay for
im the wrong guy to ask about ph
when i was running ph
dwc bucket / bubbleponics were barely showing up for sale