# [Wet Thumb Forum]-Do Power Compact Bulbs Degrade Over Time?



## Avalon (Mar 7, 2005)

I'm thinking that they do! Last year about this time, I was working on a nice planted tank with PC's, an AGA hopeful, albeit too late. Things were going well after I achieved balance. Right before thanksgiving, I left to visit the folks with a huge smile on my face. Unfortunately, I returned to find my lights in the tank and plants and fish dead--except for one molly. My glass top broke; I'd been using it for a year!

Anyhow, back in the present, I've been working on a 20g long planted tank, and I'm fairly unhappy with plant growth. Luckily, the Custom Sea Life 55w PC survived. The bulb is over 2 years old. I find that it doesn't really stimulate plant growth, only provides light for plants to live. I'm dosing CO2 and nutrients similarly to what I did in my past tank, and I'm getting more algae issues than anything, mainly green spot/dust, covering the plant leaves, killing off my glosso. I use no substrate ferts, just flourite. All ferts are at "optimal" levels.

I don't understand why my plants aren't growing as well as they used to. I know how to dose CO2, nutrients, and utilize water changes to balance things out. I've read about PC bulbs being good for around 14 months. I'm beginning to believe it. If something burns (a phosphor), it will wear out or change it's chemical composition from 'burning'. I've got a new bulb ordered to see if this makes a difference. I should be able to get it in a day or two. 

I've been told everything from 12 months to the time they burn out, but I've failed to see anyone give opinions on the effectiveness of a 2-3 year old PC bulb in relation to a new one. What are your thoughts on a PC bulbs' usable life?


----------



## Avalon (Mar 7, 2005)

I'm thinking that they do! Last year about this time, I was working on a nice planted tank with PC's, an AGA hopeful, albeit too late. Things were going well after I achieved balance. Right before thanksgiving, I left to visit the folks with a huge smile on my face. Unfortunately, I returned to find my lights in the tank and plants and fish dead--except for one molly. My glass top broke; I'd been using it for a year!

Anyhow, back in the present, I've been working on a 20g long planted tank, and I'm fairly unhappy with plant growth. Luckily, the Custom Sea Life 55w PC survived. The bulb is over 2 years old. I find that it doesn't really stimulate plant growth, only provides light for plants to live. I'm dosing CO2 and nutrients similarly to what I did in my past tank, and I'm getting more algae issues than anything, mainly green spot/dust, covering the plant leaves, killing off my glosso. I use no substrate ferts, just flourite. All ferts are at "optimal" levels.

I don't understand why my plants aren't growing as well as they used to. I know how to dose CO2, nutrients, and utilize water changes to balance things out. I've read about PC bulbs being good for around 14 months. I'm beginning to believe it. If something burns (a phosphor), it will wear out or change it's chemical composition from 'burning'. I've got a new bulb ordered to see if this makes a difference. I should be able to get it in a day or two. 

I've been told everything from 12 months to the time they burn out, but I've failed to see anyone give opinions on the effectiveness of a 2-3 year old PC bulb in relation to a new one. What are your thoughts on a PC bulbs' usable life?


----------



## imported_trilinearmipmap (Feb 11, 2003)

IMHO the people who sell bulbs want you to believe you should change bulbs every 6 to 12 months. I notice no difference now compared to 15 months ago.

Canadian Aquatic Plant Trading Website


----------



## Ron Nelson (Apr 2, 2003)

I have seen Tom Barr offer to pay shipping for someones used pc bulbs. He claims they work well enough until the day they burn out. I haven't used them long enough to form my own opinion yet though. And from most of my reading, most plants don't care too much about the spectrum shift that occurs as a bulb ages. But it seems to make sense to me that a bulb gets less intense with age, which might explain your observations. Keep us updated on the tank's condition after you replace the bulb.

On a slightly different topic: I tend to get the green dust algae you speak of (but only on my glass) when my po4 gets too low. So I try to keep it around 1ppm and that seems to help a lot. Just a random thought.

YMMV
Ron


----------



## walpurgis999 (Feb 6, 2003)

What usually causes small amounts of hair algae to cover the outside of leaves on plants?

If Gollum were into aquariums, he would say, "We hates them algae--tricksy' they are. Pokes their eyeses' out we wills".


----------



## gsmollin (Feb 3, 2003)

My opinion is that while they do not degrade like a NO fluorescent, they do degrade. I have two old ones, and they are both showing dark deposits on the glass. They are each two years old, however, and that's very good use.


----------



## Doomer (Feb 2, 2003)

Well, my experience may not be typical but when I first fired up the 4 55 watt PC's on my 75 gal. they were twice as bright as they were 2 weeks latter. Since then they haven't dimmed any more that I can tell. I have a pic of the tank I took right after I turned them on and you can hardly see anything but brilliance.









[This message was edited by Doomer on Fri October 31 2003 at 04:13 PM.]


----------



## gsmollin (Feb 3, 2003)

Doomer, it is normal for them to lose about 20% intensity in the first two weeks. It is not normal to lose half of it.


----------



## Doomer (Feb 2, 2003)

I never measured it because I don't have a light meter but to my eyes, it seemed to decrease drastically and rapidly. But once it stablized it stablized. There has been no discernable change over the past year or so. Nor has there been any hint of an electrical problem. All 4 lamps fire everyday without fail.

These are square pin CF's. Dunno if that makes a difference.

EDIT : The tank actually lokked like the pic in person. The pic is not over exposed. I remember the fish freaking out when I first fired them up. Musta burned the retna's.


----------



## JamesHoftiezer (Feb 2, 2003)

I think they do degrade over time, but its in the years. I've had a 55w going for three years with no discernable drop compared to newer bulb. If they aren't protected they could get dirty. The reflectors also might need some cleaning.

I've replaced bulbs for color, but none yet for dimming or burning out.

*James Hoftiezer
Hoftiezer.Net - Journals and Libraries
Rate My Tank!!

Tank Journal - Aquascape ( Latest / Archive(No Longer Active))
Tank Journal - Parts and Construction ( Latest / Archive(No Longer Active))*


----------



## skylsdale (Jun 2, 2004)

Coming from the reefkeeping arena, lighting is a very intensely debated subject. PC bulbs tend to lose a good chunk of their initial intensity (I think somewhere around 40%) after the first 4-6 months. After this, they burn at a much lower intensity, and over time the spectrum can change as well. This is an important issue in reefkeeping because you are wanting intensity (PAR) over your tank...but for plants I don't think it's as much of an issue. However, to say that your bulbs are fine because "they still _appear_ bright" is not a good diagnosis. The human eye is pitiful for seeing differences in intensity. ALthough 2 year old bulbs may still look pretty bright...once they are replaced with new ones the owner will see just how dim the old ones have become.


----------



## imported_csf (May 8, 2003)

I've heard that 2 years tend to be when people start to replace them. I'd try and rotate the replacement cycle (replace half in year 1, the other half in year two, repeat) to keep the light level more steady.


----------

