please helf

i am having a problem with my plants getting brown spotting on the fan leaves and then working its way to the new growth. the leaves will get spots, start turning yellow, then curl upwards and fall off. i am feeding them 2 tsp of fox farm tiger bloom and 1 tbl of big bloom. my temp is 75 on and 65 off, happy frog soil mix, ph is 6.7. please help. only some of the plants get this problem, the others are dark leathery green

How often do you feed and water them?

get some cal/mag that'll clear up the problem.

http://images.google.com/imgres?imgurl=http://www.gardenscure.com/420/attachments/plant-nursery/209849d1186314471-nursery-troubleshooting-guide-nutrient_chart.gif&imgrefurl=http://www.gardenscure.com/420/nursery-reference/105126-nursery-troubleshooting-guide.html&h=335&w=600&sz=32&hl=en&start=21&um=1&usg=__F3KMhnmZITGTZH2eDhbOvR_DScE=&tbnid=IEsbmNB-iJNiPM:&tbnh=75&tbnw=135&prev=/images?q=tomato+leaf+chlorosis+picture&um=1&hl=en&sa=X

1.https://www.rollitup.org/marijuana-plant-problems/132382-deficency-nute-burn-diagnostic.html