Hi wazzy, each light come with a set of yoyo as the free gift, you can adjust the hanging height of YOYO between the light and plants.
Here are some recommended lighting tips that may be helpful:
1) Seeding Stage: Distance between light and plant:24"---on/off time :18/6 or 20/4
2) Germination Stage: Distance between light and plant: 24"-30"-- on/off time :18/6 or 20/4
3) Vegetable Stage: Distance between light and plant: 18"-24",-- on/off time : 18/6 or 20/4
4) Flower Stage: Distance between light and plant: 12"-18",-- on/off time :12/12
Recommended Growing Conditions:
1)PH Value: 6.0~6.5 in soil; 5.7~6.0 in hydro/DWC. More cal/mag and water+nutrient less
2)The rate of photosynthesis and transpiration are directly affected by temperature, humidity and airflow. The recommend perfect temperature and humidity for your plants are found between 75°-85°F and 50% - 70% humidity, with plenty of airflow to replenish CO2.
Notice:
The information above are summed up based on the data which given by buyer actually planting.