Time for a new light fixture ?

Henry Hatch

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Aug 31, 2006
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I've recently developed some brown algae (diatoms) in an established 30 gallon tank. The bulbs are 2 t8 30 watt NO flourescents less than a year old in a fixture 8-10 yrs old.

I took some PAR readings which varied from 35 to 54 at the substrate with the lowest readings near the end of the bulbs. I don't have readings for when the bulbs were new since I just got the meter recently .

The fixture is old but has not had continuous use. I have also noticed slower growth. I did not have this problem before. Same bulbs same fixture. Is it time to replace the fixture or the bulbs ?

Henry
 

VaughnH

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That is low light intensity. Do you want a non-CO2, low light tank? I think new bulbs would give quite a bit more intensity, and as I recall, T8 bulbs lose a lot of their intensity before a year of use. If you haven't already done so, you could paint all of the area in the light fixture, around the bulbs, with ultra white paint, and possibly get some more light.
 

Henry Hatch

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Aug 31, 2006
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VaughnH;34293 said:
That is low light intensity. Do you want a non-CO2, low light tank? I think new bulbs would give quite a bit more intensity, and as I recall, T8 bulbs lose a lot of their intensity before a year of use. If you haven't already done so, you could paint all of the area in the light fixture, around the bulbs, with ultra white paint, and possibly get some more light.


Actually I do run co2 and recently went from 2/3 EI dosing to full EI dosing. I'm thinking of running t5 HO on the tank. I have a 20 gallon H with T5 lighting which has been doing pretty well with excel. I guess NO flourescents degrade much more quickly than most HO bulbs. I think in the long run T5's will be cheaper.
 

Henry Hatch

Guru Class Expert
Aug 31, 2006
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I just put in 2 new bulbs. The PAR readings went up significantly. I checked back in my records and found that my t8 NO bulbs were about 10 months old. I was surprised at the amount of fall off in intensity over less than 12 months. This confirms the value of the PAR meter and the relatively short useful life of NO flouresents. After these bulbs die I will replace with a t5 fixture.

Henry