Green veins, yellow patches between veins?

What is your experience level? first timer

Your Equipment:
.1) Type and wattage of lights. 200w CFL
.2) Distance from tops? 10"
.3) Reflector type? none, in small white room
.4) Is there a consistent fresh air supply? yes
.5) Do you have an exhaust fan and a circulation fan? yes
.6) What are the bulb wattages, kelvin ratings, and schedule? 200w, 5000k, 18/6

Your medium:
.7) Specific brand and type of soil, (coco, peat based soilless...) and anything you've added to it. (vermiculite, perlite, worm castings...) Miracle Grow Gardening Soil (Trees and Shrubs), added nothing but nutrients
.8) Size of container. large styrofoam cups
.9) Did you use peat pucks (or similar) to root clones or germinate seedlings? no

Your nutrients and water:
10) Source of water? (tap, bottled or filtered) What's it's ph before adjusting? tap, about 8.0
11) Method of checking water ph. (ph pen, test strips, aquarium test kit...) aquarium test kit with clear tube and drops, color chart
12) Method of adjusting water ph. (phosphoric acid, white vinegar, hydrated lime, PH Up...) phosphoric acid
13) Specific brand and N-P-K ratio for each bottle. List dosages (quantity per gallon) and current feeding schedule. Sensi Grow A, Sensi Grow B
14) How often are you watering between feedings, and how much per watering? 4-5 days, water about the same amount as the cup has dirt
15) Any additives or tea's? (Superthrive, CalMag, molasses, Mother's Earth...) no
16) Are your ph levels stable, or do they fluctuate? ph levels fairly stable (but little high) only been testing soil ph last few days
17) What is your ingoing water's ph? ...your runoff ph? last night I tested it, 6.4 water in and around 6.7 water out
18) Do you foliar feed? If so, with what, how often, and at what time do you spray? no

Your growroom:
19) Indoors or outdoors? indoors
20) What size of closet, room or hut? big enough
21) What are the temps and humidity levels while lights are on? ...With lights off? low humidity, 75-80 degrees
22) Have you seen signs of insects in the growroom? a few small black insects from the soil

Your strain:
23) What strain are you growing? (Indica dominate or Sativa dom?) sativa
24) From seeds or clones? seeds
25) Is this an autoflower strain? no idea

Alright, so I have some plants that are about a month old and began showing yellow on their lower leaves 10 days or so ago. Thought it was a N def. so I fed them twice over a week or so. The leaves turned almost completely yellow and I think it was due to an N lockout because the soil ph was really high(8ish). So I flushed the soil several times with about ph 6.5 water and the plants seemed to like it, they grew a little faster for a couple days and then slowed down again. Tested the soil ph last night, still too high, flushed them again with 6.4 water... got flush results of about 6.7-6.8. So my guess is the soil is still too high (ph7.2 range?). Suggestions? Anyways, I've began to see light spots in between the veins on the leaves, the leaves are dark, but the rest of the leaves are light. Is this the soil still locking out nutes? or something else? THANKS!

Are you able to post a pic? Why I ask, is I'm trying to reconcile a month-old plant in a styro cup. Normally a month-old plant's in a bigger container, I think. If you're rootbound, it'll cause those symptoms, including nute lockout.

Your guesses seem good. When I flush it's a slow, loving process. :giveflower: You have to give the salts and corruption you're trying to get rid of enough time to dissolve and be rinsed out of your medium. (The old rule of thumb is to flush with 3X the pot volume.) But if you measure the EC (ppm) of your runoff, you can watch the dissolved solids level drop with each flush till you get it where you want it-- a cheap EC pen would be a big help. You may want a pH pen, too.

But you're doing it right (well. the way I think is right ;)): see how much the soil is raising the pH and shoot low to compensate. Never shock the plants with a flush that's more than a point off ideal, though.

Don't know where you want your pH, but I've seen strains that seem to prefer soil under 6.0, despite what I've read. And some sativas are comparatively light feeders, they don't use up much nutes so your soil gets "hot" fast.

Unrelated to your problem, I'd get some kinda reflector on your light source. No sense wasting those watts / photons bouncing them off the ceiling.

HTH, Hermie

Hehe.. well I admit I'm a newbie. The plants are small for their age and I'm not positive that isn't because of the ph problem as well. Most of them are about 5" tall.. :wtf: Pics this time...

A brief background is I germinated the seeds, placed the seedlings in the miracle grow gardening soil, and started watering them 1-2 times a week - didn't check water ph. At the time I didn't realize how important ph is.. about 2 weeks in I thought I would feed them (not realizing that the soil already has some food in it) so I mix some Sensi A and Sensi B (food solution) and give them each a watering.

Shortly thereafter I started to notice the leaves on the bottom turning yellow. Now up to this point I had been watering with tap water and feeding with food mixed in tap. (My tap tested to have a ph of 8..ouch) So I started trying to figure it out, but kept thinking it was an N def problem..which didn't make any sense because I had been feeding it N. So like an idiot I gave the plants a little more N. Then I thought it might be a ph nutrient lockout...something I had read about.

So I start testing my soil and realize its ph is super high, about this point some of the plants start to show what I think is chemical burn (crisp dead spots on tip/edges of some leaves).. so I start trying to get the soil down with a ph down solution designed for hydoponics. I make a big batch of about ph 5 (didnt know about the shock thing yet) water and rinse it through, lowering the ph a little...and then a couple days later I rinsed with ph 6.4 water again. The water that was coming out was still a little high (6.8ish water, 7.2ish soil?), so I'm probably going to flush again.

And then I started seeing these yellow spots between the veins...ideas? If you've read all that and have any input.. Thanks :weedpoke:

Well, operator error doesn't show up immediately in soil (as opposed to coco, hydro, etc.) so what you're seeing was caused by conditions a few days ago.

Whatever yellowing, splotches, etc. you've got going are probably not gonna heal. When you get things right, the new growth will be good, though.

I really can't see in those pics well enough to make a call, but why bother? You've got a few things you know need correcting (pH, nutes, maybe pot size) and any of them could have caused you problems.

Soil: Seedlings don't need nutes, the seed provides it. Usually stuff called "potting soil" is what you want, just peat with maybe some perlite, etc. but no nutes. I've never used the MG you mention. But ferted soil with extra nutes--ouch! Your seedlings' roots are gonna look like Oldmac gave 'em a bad perm. :D

Small containers: When that cup dries out a bit (which it's supposed to do between waterings), the concentration of your nutes can increase dramatically as the liquid volume decreases. Use LIGHT ferts. It's a weed.

Do you know how to tap a plant out of its cup without destroying the roots? That's the first thing I'd do. If it looks rootbound, move to a 1gal container with 1" of stones in the bottom (more if your soil doesn't drain well). Water well, measuring the runoff pH, and get that stabilized in the correct range. If it's that MG ferted soil you probably don't want added nutes at this time. Depends on how fast they're released in that soil. :what:

So, my answer is: I don't know which condition(s) are causing your problem. But if you transplant (if needed) and flush, and maintain proper pH and nutrient levels, you'll eliminate some obvious possibilities which will need to be fixed eventually, anyway. :thumbsup:

Show me your roots? :D

Thanks for taking the time to help... I'll check out the roots and keep an eye on the ph. Give it a few days and see what they look like. Thanks!