purple stems and brown spots

ok am into day21 of 12/12 all looks not to bad buds forming nicely but hav noticed stems on fan leafs are turning purple in colour and that some of large fan leafs hav small brown spots all over them,is this an over watering problem or am i not feeding enough?? any help please.this is my first grow.plants in 7 1/2 litre pots are bout 3 ft tall in a good quality potting compost mixed 70/30 with perulite ,soil ph is 6.8-7.0 water am using is 6.5 ,get watered every 3rd day and soil always is well dry on top anyhow when watering,am feeding once a week at min n.p.k is 14.10.27.

sorry forgot my temps never higher that78-80 and drop around 60 when lights out.as am new to this and wasnt to sure todo or not so just didnt,was to spray or mist the plants.EVER!!!.lol.any help please.

it might be overfertilizing actually, give the plants water and wait about a week. if nothing happens, or it worsens, try adding a little more potassium to the fertilizer

... i'm pretty sure its over fertilizing though. do you have any pictures?

will take a few and post later,when i use the feed is only half strenght which i thought would be on the sfe side of things but will post a few pics to see what u think.many thanks app the help.

am havin probs getten pics up but hav noticed this morn that one of my plants is turning a very light green rather than the usual dark green,has anyone any ideas???

most flower nutes use less N than veg since its not needed so the plant will turn lighter green from a N def. also do you have an EC/PPM meter post the EC you have in your nutes and your PH could be a ph issue locking out nutes or if there is too much of one nurient it can lock out another

dont hav one of those meters yet ,do u advise in getting one,soil ph is 6.8 .feed am using at min is 14.10.27 at half strenght once a week.

yes soil ph test strips are not that accurate

ok got a moisture and ph probe ,will get ec/ppm meter somewhere tomorrow.reading alot diff than what was getting with ph strips and soil test kit.with new probe my ph soil ph readings over the 5 pots are anything from 5.8-6.2 ,plain water ph is 6 and with nutes added is 4.8??? anyone any ideas please????

ok hav been given them just water all week and doesnt seem to be getting much worse but certainly not getting any better ,ph is around 6.3-6.5 ,do i feed or not.anyone any ideas please.

bump LOL

bump LOL bump LOL