is this normal during flowering

[topsykrets]

I have some smaller leaves that turn evenly yellow and the entire branch falls off(these are not my concern)

I also have very yellow fan leaves that are turning brown but dont fall off. and dont look healthy. my pictures didnt come out very well due to the amber color of the hps lighting so I took one fallen leaf and took a picture of it.


What type of medium; soil or hydro? soil
What brand and type of soil? ffof
Indoors or outdoors? in
What strain? northern light X big buds
How old are the plants? 6.5 weeks total 2 weeks and 3 days into flower
What type of lights and how many watts? two 1000w hps on 7 plants
How far from the lights? some are 18" and some are too tall and have passed the lamp height... I have moved these to the sides of the light to get about 12" lights are aircooled with a 745cfm fan so they dont get too hot. 82f

What is your watering frequency and source of water? ro they get thirsty about every 2-3 days (look wilted and sagging)
What, how much and when was it fed? NPK? 1/2 fox farms weekly schedule
What is the medium/runoff pH and PPM if in hydro? ?
What are the temps and humidity in the room? rh 54% high/low 84f/68f
What size pots? 3gal
Any bugs? Look real close. fungal gnats
Any other pertinent info? dark briown spots are only on 2 plants..... note about plants in the first picture-> plants on left are about 4ft tall, while the plants on the right are over 6ft!!!


and my ph meter broke so I use the test drops to get close 6.3-6.8 ish

[schmedrickk]

Hi there,

Nice plants, you should get some great buds off them, but the trick will be bringing them to the finish line.

The problem your leaves are displaying show all the symptoms of a Calcium/Magnesium deficiency. If I understand the answers to your questions correctly, it appears you are using Reverse Osmosis water as your source, is that correct? If so, you might want to check this out:

Reverse Osmosis Pros and Cons:

Reverse osmosis is a valuable water purification process when mineral-free water is the desired end product. Most mineral constituents of water are physically larger than water molecules. Thus, they are trapped by the semi-permeable membrane and removed from drinking water when filtered through a reverse osmosis system. Such minerals include salt, lead, manganese, iron, and calcium. Reverse osmosis will also remove some chemical components of drinking water, including the dangerous municipal additive fluoride.

http://www.allaboutwater.org/reverse-osmosis.html

When you measured your PH level (by the way PH drops are the only way to get an accurate reading) was the 6.3 - 6.8 reading before or after you added your ferts to the water? FF ferts will take down your PH level hard if you aren't careful, so it's critical to measure the PH after the ferts have been added to the water. If the PH reading is after adding ferts to the water then you should be fine, but the real problem you may have is the RO system is stripping out other vital minerals and trace elements that your plants need.

Most ferts are very low in elements such as Calcium and Magnesium, so unless your soil has an adequate amount of them, you're going to have a problem.

I would recommend using at least one plant as a test case and get hold of a bottle of Cal-Mag nutrient supplement, and give it a feeding of 2 tsp to a gallon of Non RO water. This wouild be in addition to your normal feeding schedulle of ferts but be careful you don't dilute the Cal-Mag feeding with other fert solutions. I think the real issue may very well be the RO water.

At this point your plants have a problem, and you'll need to do something or you could lose them if the problem becomes severe enough. From the looks of the pics you provided, the problem already looks pretty severe.

Ultimately the choice is up to you in terms of how you wish to proceed, but I personally think this could help.

[topsykrets]

yes i am using the reverse ossmosis...... I will set water out tonight so that the chlorine can evaporate.....

thanks