babygro
Well-Known Member
No HID light should ever be within inches of the canopy even if heatwise you could use it there. In any case it would be stupid to use it so close as what you might again in light depth penetration you'll lose in distribution across width and depth as the air cooled hood is so low. So by using your hood so low to the plant canopy - the lower areas may receive more light but the plants on the edges of the grow space will recieve less overall.you can use an hps for a stealth grow no ones ever heard of air cooling and the light can be within inches on the canopy
And don't mention Cool Tubes either - their light distribution and spread is shit, the internal reflector is virtually useless it's so tiny.
The one thing people really do forget about with HIDs is the sheer amount of infra red radiated heat they give off - and the closer the plants are to the HID bulb the more direct radiated heat they receive - this just serves to dry out the top cola.
You can't exhaust radiated heat, because - it's radiated! It's not like inductive heat you get from the oven or a heater which you can exhaust. It's the same principle that heats up your food in the microwave and the same principle that burns you at the seaside despite the fact theres a strong wind blowing, except that's obviously ultraviolet radiation - but it's still radiated.
It's this radiated heat that causes problems and heat build up in small grow spaces - not the inductive heat you're conveniently exhausting with your exhaust fan.
This is precisely why my advice to people using HIDs asking for guidance on how far it should be away is always greater than everyone elses recommendations - because I factor in and allow for this radiated heat - others do not.
Putting a HID in a small closet or wardrobe is nothing like as simple as people make out - it can be done obviously - but you must allow and deal with the excessive heat build up - inductive as well as radiated.