its 645watts 'from the wall'
and yes, that does help - so you run full 400watts at 24" with tender new seedlings? If so, sounds like I need to turn up the wattage/dimmer a lil on my grow
Yes, I run my freshly planted clones (immediately after removal from my aerocloner), as well as freshly sprouted seedlings directly under my 400W MH, about 24" above the plants.
I'm not suggesting that you bump up the output of the lamp, but I'm not telling you not to either. Realistically, the environment (temp, humidity, airflow etc) all have bearing. For example, if there's no airflow and the light causes the temp to go up too high, that can hurt the little seedlings. More light means more heat which translates into a reduction in humidity, and seedlings like a higher humidity environment, so discretion is always needed.
The veg tent that I put these seedlings in is at 50-55% humidity, 77F temperature, with mild airflow inside the tent.
Always let the plants tell you what they need, and only change one thing at a time. If you bump the output of the light, don't change anything else for a couple of days so that if a problem does come up, you know precisely what caused it (turning up the light too much).
You should also note that the higher the light intensity, the less stretching the plant will go through to reach for the light, so there will (typically) be shorter internodes, resulting in a shorter and more compact plant. If there isn't enough light, the plant will (again, typically) be lanky and tall, with longer internodes.
