View Full Version : how do old bulbs cause problems

01/04/2007, 08:16 PM
How or why dose old bulbs cause algae?

01/04/2007, 08:45 PM
I am not an expert at all but I think it has to do with the way the bulbs lose intensity as they get older. This lower intensity puts the light output at a level more appropriate for algae growth.

I can speak from first hand info, VHO lights lose half or more in six months. It took losing some nice corals to discover this problem.

01/04/2007, 08:50 PM
Ok thanks for the info. I have 192 watt pcs at 10 months old and alot of algae starting and was just wondering.

01/04/2007, 08:51 PM
The optimal spectrum gets diluted. This causes a shift in the spectrum which as scbasser said provokes algae growth.

01/04/2007, 08:54 PM
So when should they be replaced? And what are the best bulbs to buy? Also dose anybody know what a good site is to buy them from?

01/04/2007, 08:57 PM
Halides 8-10 months
T5 6-8 months.
PC 7-9 months

This is off the top of my head so don't quote me on it.

01/04/2007, 09:00 PM
WOW!!!! I'm really past due then. You have any suggestion as to were. I need 2 bulbs and went to my lfs and they wanted 65.00 a piece thought that was high seeing that I didnt even pay 130.00 for my retro fit.

01/04/2007, 09:09 PM
I'm guessing you're using PC bulbs? I don't know too much about them. Try using this search engine and see what you can pull up.


01/04/2007, 09:52 PM
hellolights.com has always been good to me. Good prices too.

01/04/2007, 10:00 PM
when your halides go bad you know. i learned from experience trying to milk them. algae issues big time. changed the bulbs and all is well. trust me dont milk them, took a while to get all the funky algae gone

01/04/2007, 10:36 PM
The filament inside the bulb looses value over a period of time. The human can not detect it though. I have read more articles than I could imagine and from what I read more times than other is that Halides get 6 months for mogule, 7 for square pin. Poewr Compacts 12 months and suprisingly, a VHO gets 12 months. All of these numbers depend on the bulb manufacture, hours per day used and type and quality of ballast used. Electrical surges also. I have run VHO for a couple of years over my reef and they last for 10-11 months. I switched to power compacts for a while and they lasted 12 months. I saw better results with the VHO's so I will return to the VHO bulbs.
If you run more than one bulb, space out the bulb swap by waiting a few weeks until they are all changed out. Or, you could run a new bulb in the basement, garage or something for a week, letting it stay on for twenty hours at a time. This way you are not shocking your livestock.
You could also invest in a lux meter and that will take the guess work out and it saves you money in the long run.

01/05/2007, 08:35 AM
I have had my PC bulbs for about 22 months. In the past month or so my goby died and the sand has not been stirred - I am just now seeing algae growth. It could be related to the bulbs or the lack of sand movement.