Looks fine to me. I got it one time as well. I thought(when I had it) it is because the nutrition solution was not lvled right and the nutes lvl was to high. Have no idea if it was right(my thoughts) and have no idea if it is the same in your case.
Get you some Silica Blast from Botanticare, you will see a HUGE difference in growth, this will strengthen the cell walls of your plant, and strengthens the plant overall, Its a MUST HAVE! In my opinion. I went for along time without using a silica, now i could never see growing without it. I start adding silica to my plants at about 2 weeks into veg, and continue to use it until about 2 weeks before they are finished. THe last two weeks of the plants life i only use plain RO water to flush out all the left over nutrients.
Are you using a fan to blow on the plants, to circulate air and help strengthen stems? I see the area just above the stones where the stem looks narrower. To me, it looks like a fan was blowing too harshly when the plant was younger, causing the stem to rub against the stones. Is that possible?








If a cannabis plant is affected by a calcium deficiency for too long, it may begin to show the following symptoms due to the lack of calcium.
Stems become weak or flimsy and may crack easily
Stems become hollow or show inner signs of decay
Plant does not stand up well to heat
Flowers/buds do not develop fully, or development is slow
Roots appear weak or under-developed
In severe calcium deficiencies, parts of roots may even die off or turn brown
Roots are more susceptible to root problems like slimy root rot
Cannabis tends to like high levels of calcium, so it is unusual to feed too much calcium when using normal amounts of nutrients and/or regular soil. There are not many known cases of cannabis calcium toxicity (too much calcium), however too much calcium can cause the plant to lock out other nutrients, so it's important not to go overboard..
Calcium deficiencies are more likely to appear when...
Grower is using filtered or reverse osmisis (RO) water to feed plants - the amount of calcium found in tap water varies, but some tap water has enough calcium to prevent calcium deficiencies
Growing cannabis in hydroponics with nutrients that don't supplement calcium or when growing in water that has less than 6.2 pH
Growing cannabis in coco coir that hasn't been supplemented with calcium or below 6.2 pH
When growing in soil or soilless growing medium that hasn't been supplemented with calcium (usually from dolomite lime) or is acidic (below 6.2 pH)
Too much potassium can also sometimes cause the appearance of a calcium deficiency
Outdoors - calcium deficiency is more likely to appear in acidic soil (below 6.2 pH)









