The plant is growing in hydroponics using General Hydroponics nutrients and following their feeding chart. It's an indoor grow. The strain is Liberty Haze. The plant is almost two months old. The reason it's really small is because the grower used T5 lighting to grow it at the beggining (about 20,000 lumens, 6500k) until just recently when the grower bought a 400 watt HID light to grow with. When using T5, the lights were 6" - 12" above the plant, now the grower is using both lights and they're both at two feet above the plant. It's not hot near the plant, the grow room is 76 - 78 F in temp when lights are on. A fan keeps fresh air circulating. The grower has a humidifier but the humidity only gets up to 50%. The pH is around 5.5 all the time. It never changes. The PPM is around 1000 - 1400. The size of the pot is 5 gallons with only two gallons of nutrient water inside. It's aerated with an air stone. The grow room also has a small air ionizer to reduce smell. The grower noticed one or two bugs in the grow room which the grower killed instantly. Some of the damage on the growers leaves look like they've been eaten by bugs. If this is the case, what can the grower do to keep the bugs out or kill them when they get in? Also, there's light colored spots that have done physical damage to the leaf that's been around since the plant has started growing. It's never been a big issue until now. The grower has tried to figure out what it was in the past with no luck so the grower just hoped maybe it would go away over time. Also, the stems at the top are turning a purplish color. The grower has had this problem earlier on but it went away until now. Forgot to mention, the grower changes the nutrient solution once a week. The grower cleans the bucket good and uses RO water. Anyways, here's the picture of the plant. Hopefully you have all the information you need and maybe someone can help the grower figure out what's going on. Thank you.
Possibly slipping in Mg. I'd raise the ph to 5.8, drop the light to within about 12 inches and test with the hand over the plant long enough to determine if it's uncomfortable or not, of no, leave it at 12 inches, if so, raise it to 14 inches about canopy and test. Light needs to be as close as possible all the time. http://hydro-heaven.com/yahoo_site_admin/assets/images/ph_Chart_3.208114926_std.gif Probably lower the ppm's also: http://www.mandalaseeds.com/Guides/Fertilizing-Smart-Guide
Yes, the grower can tell from the tips that it may possibly be nutrient burnt so the grower has lowered PPM. The grower will add in more magnesium also. But the grower can't help but wonder if there's something else that may be causing those spots that form on the plant leaves.
All the grower has to do is lift the ph to 5.8 and nutrient uptake of Mg will be more readily available.