Re: T8 vs T12

To: Aquatic-Plants at actwin_com
Subject: Re: T8 vs T12
From: George Booth <booth at hpmtlgb1_lvld.hp.com>
Date: Mon, 13 Nov 1995 08:43:56 -0700
In-Reply-To: Your message of "Sun, 12 Nov 1995 03:39:02 EST." <199511120839.DAA00839 at looney_actwin.com>

> From: gtong at sirius_com (Greg Tong)
> Date: Sat, 11 Nov 1995 19:15:53 -0700
> 
> I'm really surprised at George and other's measurements of the lumen
> depreciation from their fluorescent lamps. There must be other factors
> at work because commercial places certainly don't need to replace
> their banks of fluorescents every two or even twelve months.

Not surprising at all.  The human eye is a very poor judge of
brightness.  As long as the ambient light level is adequate for
whatever activity is taking place, the lighting is "fine".  Most homes
or offices don't replace bulbs until they burn out or start to
flicker. 

The lighting over my plant tanks is merely adequate compared to the
intensity of the sun (15,000 lux vs 95,000 lux).  I want plants to
grow as well as possible and try to keep the lighting at the merely
adequate level instead of the sub-adequate level, hence I change bulbs
often.  Your results will vary.  

As an engineer, I know how engineering specs get "translated" by the
marketing and advertising people and I don't trust them.  

George