Main factors which affect performance

- environment...you should have a day time temp of 75F / 50 rH humidity and night time of 70F / 50 rh humidity. Get this right and growth is dramatic.

- don't over fertilise. If your plant leaves are very dark green, that could mean you need to reduce the nutrient strength. Black tips means you've over fertilised. Once you've done this, run the hydroponics systems on water/flush only until the leaves start to go lighter green.

- plants are too close to the light....make sure there is at least 36" from the light to the top of the plants.

- genetics. If you have poor genetics, the plant won't perform very well anyway.

Problems

Smell - install a carbon filter. Ensure the area is sealed up very well. A carbon filter should be ran 24/7 to ensure no smell.

Insects - if you get a insect/mite problem use Pepper Wax or predator mites.

Plants stretching - move them closer to the light or add more light

Baby plants stunted and not growing - if the environment is OK and the nutrient is correct, then it could be too much light too soon. Baby plants do not respond well directly below the bulb - move them off-centre away from the bulb.

High humidity - you need to change the air with extraction and dry the place out using circulation fans.

Low humidity - put some water in buckets in the grow room and it will raise humidity.

Too much heat - use circulation fans and extraction fans. Failing that, reduce temperature by reducing light. 85F and above is a non-growth zone for many indoor plants.

Not enough heat - add heaters such as oil filled radiator but be careful safety-wize. Insulation is a better solution.