08-30-2010, 06:19 PM
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Originally Posted by migdem
These bulbs are the Juwel make. They do not have any Kelvin rating for them. I will get the Day Lite then. Also in the website they suggest to be changed every year because the light will deteriorate and plants will not stay healthy any more. That is why i am asking here to see if this is true.
There is varying opinion. Some run them until they actually burn out; I don't recommend this because there is no doubt that they do deteriorate in intensity as they burn, and it is also a fact that algae increases when they are left this long which means the intensity is no longer sufficient for plants. Some say 6 months or 1 year--but as I mentioned previously that applied to the T12 tubes. Karen Randall of the Aquatic Gardeners Assoc. in the 1990's recommended 6 months to 1 year max. But the new T8 tubes are different; they use less energy, they produce higher intensity light and by different means in the way they are made. Diana Walstad, Tom Barr (if memory serves me), Peter Hiscock have all said 3 years.
The website is out to sell their products, and unfortunately this has to be remembered when you are taking "advice" from manufacturers or retailers. I used to replace my T12's every year. I now have T8 tubes and since installing them in October 2008 and July 2009 I have not replaced them and I intend to go 3 years before I do.