Change Plant Lights Regularly

[sostoudt]

T5 HO lifespan is 20,000 hours if you leave them on 100% of the time, and they certainly lose far more than 5% of their output over a far shorter span of regular use. Typically you can get about 5000 hours out of a t5 ho before they are no longer producing a 50% or greater comparable PUR to intial installation.

Secondly, your PAR and PUR begin to degrade as soon as the bulb is first utilized as the molecules in the "filament" are deionized over time through vaccuum leak and reaction with atmosphere. The cheaper the bulb, the faster this happens. The reason for this is that the energized ions of fluorine, and whatever heavy metals added to the bulb for temp, begin to bond with the various gasses that leak into the tube, shifting the spectrum of radiated light.

whats your opinion on regular flourscent, and pc's then?
you dont have to have a link to a par graph over the lifetime do you? thats what i was really looking for but couldnt find one.

 

[velanarris]

It's about the same curve for all fluorescent bulbs with the exception of power compacts. PCs last longer because they aren't capped, they're molded shut.

A PC can sustain PAR and PUR for about 25% longer, so I'd say 9 months to a year for those. But once again, it depends heavily on the manufacturer.

 

[crenicichlacrazy]

I change my T5's every 8 months and I don't even have plants.

 

[skiptomyzoo]

I thought it was the the PAR value (photosynthetically active radiation value aka what plants use for photosynthesis) that mattered more than the actual visible intensity of the light, meaning that your eye is not always the best indicator of when to replace bulbs as in this case. Therefore, lights that appear dimmed may still may be meeting diminished yet still acceptable PAR values and therefore not need replacing yet, which is why people use meters to check such.

I'm pretty new to planted and such, so please correct me if I'm wrong.

 

[velanarris]

PAR is a component of intensity.

PAR is the light that is active in photosynthesis
Intensity is the strength of the light

If your intensity drops the PAR also drops.

 

[sostoudt]

PAR is a component of intensity.

PAR is the light that is active in photosynthesis
Intensity is the strength of the light

If your intensity drops the PAR also drops.

i wouldnt say its so cut and dry. you could have a very intense light that has very little par.

bulbs in a blue spectrum tend to put out less par then lights in a red spectrum.

 

[skiptomyzoo]

PAR is a component of intensity.

PAR is the light that is active in photosynthesis
Intensity is the strength of the light

If your intensity drops the PAR also drops.

i wouldnt say its so cut and dry. you could have a very intense light that has very little par.

bulbs in a blue spectrum tend to put out less par then lights in a red spectrum.

velanarris, if you reread my post you will see that I said that but more elaborated , so I am confused as to what point you are trying to make? Sostoudt pretty much finished my train of thought on this, and I am going to have to agree with him, esp. in the sense that lighting intensity doesn't have everything to do with par, otherwise you could use any bulb as long as the intensity was around the same, but that is not the case. Hence, my point that the intensity could be diminished, but it could still be meeting good PAR levels, so how dim/bright a bulb is, isn't always the best indicator like i said above.

 

[velanarris]

Ok guys, you're reading it backwards.

PAR is a component of intensity.
Intensity is not a component of PAR.

PAR can fluxuate without a change in intensity, but if your intensity wanes your PAR also wanes.

Yes, there is more to it but I'm fairly sure no one wants to perform integral calculus every 6 months.

 

[sostoudt]

Yes, there is more to it but I'm fairly sure no one wants to perform integral calculus every 6 months.

i do show me how to do it!

seriously i do want to know a better way to predict par degradation