how many crops per bulb

[Tom]

I dont think there are many bulbs on the market that last less than 10,000hrs. Dont be fooled into beleiving that bulbs need changing every 1to5 crops. Its a ploy used by the shops for u 2 buy more. A myth that has developed over time by neglecting the mathematical truth.

No mate, it's something that most experienced growers are aware of and many have seen the difference first hand, Worn Lights.

Globes wear down to a stage where it is good economic sense to replace them after at least the third grow, the increase in yield more than covers the cost of replacement.

 

[F420]

I have noticed for sure that the 4th and up are shit, the plants stretch more for one.

[fordute]

No mate, it's something that most experienced growers are aware of and many have seen the difference first hand, Worn Lights.

Globes wear down to a stage where it is good economic sense to replace them after at least the third grow, the increase in yield more than covers the cost of replacement.

 

<{POST_SNAPBACK}>

 

Eventhough u r right when saying that crop yield is effected, a bulb will not dramaticaly affect crop yield until about 75% used. Meaning that a life of 20,000hrs is reduced to 15,000hrs translating into about 10 crops taking about 1,300hrs of bulb life each crop. I have tested this and proved that u r right as yield was reduced by about 25% after the 8th crop using the same bulb.

[Guest niall]

Surely the "lifetime" of a bulb is different to the quality of light it is producing. The bulb may last 20,000 hours or whatever, but if it's losing lumens then there'll be a point where the effective life of the bulb is over. It may still be producing light, but it would be far enough from its optimum output to justify buying a fresh bulb.

 

Unless you've got lumen calculations, you can't just base your buying decision on what the manufacturer rates the bulb as its "lifetime".

[Skunkxxx]

HUMMM ....FOOD FOR THOUGHT THANKS

[fordute]

Surely the "lifetime" of a bulb is different to the quality of light it is producing.  The bulb may last 20,000 hours or whatever, but if it's losing lumens then there'll be a point where the effective life of the bulb is over.  It may still be producing light, but it would be far enough from its optimum output to justify buying a fresh bulb.

 

Unless you've got lumen calculations, you can't just base your buying decision on what the manufacturer rates the bulb as its "lifetime".

<{POST_SNAPBACK}>

 

Bulbs emit between 3,000 & 10,000 lumens per square foot and a plant can do well down to 1,500 lumens. A bulb looses about 3% lumen every crop cycle based on 1,300hrs. So if a new bulb starts at 5,000 lumens and looses 3% every crop and plants do well down to 1,500 lumens you will get 8 crops until the bulb deminishes below 1,500, eventhough indica flowers best above 2,000. With a photgraphers light metre the lumens can be measured to ensure accuracy.

 

Natures herb can grow anywhere even on antarctica and yield is very much determined by the environment in wich it is grown (including light) To maintain yield during extended bulb usage the vegitation cycle was slightly extended every crop leading to an increased flowering stage. Flowers are smaller & stems stringier but overall quantity and most important quality was maintained.

 

I documented a 2 year trial on different bulbs. If you are interested I can post all the findings. I am in no way indicating to base the desicion on my findings rather to share opinions and experiences with others.

[Guest niall]

A bulb looses about 3% lumen every crop cycle based on 1,300hrs.

 

I documented a 2 year trial on different bulbs.

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Fair enough ::

[jackfrost]

I change all bulbs every twelve months 5-6 crops easily - usually use 1000watt per 1.5m2. Notice slight decrease in growth on last crop (but only slight).

 

Jack