Light distance

there FC and FCE are powerful lights. they will be great for a 12 hour bloom schedule. 100% at 18-24" to start.. let them stretch how you like.. then let them rest 16-20" after stretch ends. Watch for any bleaching of top colas... environment will be a big factor of how much they can handle, so, take any recommendations lightly and always observe and react to the plant. Watch resulting length of internodes.. if it gets too stretch or tight up top, adjust light. because of the reduced hours, should be fine at 100% and that distance. If you use it in vege, becareful. You try 100% for 18hours and you will stunt your plants. It's all relative. So you need 66% of the power at same distance, all other factors remaining the same. I prefer to raise the light a bit and go up to 75% on my fc 4800. More photons spread out, more coming in from odd angles off walls. slightly more electricity, but gives good penetration/immersion. Again, observe and react. Resulting Internode length will be the guide.