# How often should I replace bulbs?



## raven_wilde (Nov 16, 2005)

Just a quick question: 

About how often should I replace the bulbs in my tanks? Just asking because I've noticed that the plants in my 30 gal do not seem to be growing as quickly as they have in the past... the bulb is well over a year old and I was wondering if this was the issue... it's a very low light tank so if it is starting to go I imagine the effects would be almost immediate.


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## SnakeIce (May 9, 2005)

When I had two 15 watt bulbs over my 20 gallon I had to replace them at 6 months of use as growth had come to a stand still at that point. Now I was useing cheap GE plant and aquarium bulbs so that may have limited the use I got out of them over some more pricey bulbs. I devised a alternateing replacement schedual so I got more even growth. I would replace the oldest one every three months, so I had at worst one 6 month old and one 3 month old over the tank.

If you have more wpg my theory is that you can get away with useing the bulbs longer befor you notice the plants not growing as fast. 

I have wondered if one tank with 2.5 wpg could be considered low light while another tank the same size with 2.5 wpg could be considered high light just because of how long bulbs are used. If the "high" light tank's bulbs were replaced after only 4 months use and the "low" light tank's bulbs were only replaced after a year or more of use. This would be for regular flourescents, since pc bulbs have alot longer lifespand for example.


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## raven_wilde (Nov 16, 2005)

Well, the tank I am referring to is about 1 wpg... so I think maybe it is time for a new bulb.


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## John P. (Nov 24, 2004)

As long as my Glosso stays horizontal, the bulbs will stay.


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