Idiot Can't read tester

quantum

Well-Known Member
Hey guys, i have one of those Rapitest light testers with a scale from 0 to 2000.

What do these numbers mean, and what is the minimal reading i should have in veg.

I hope 500!
 

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rkm

Well-Known Member
Hey guys, i have one of those Rapitest light testers with a scale from 0 to 2000.

What do these numbers mean, and what is the minimal reading i should have in veg.

I hope 500!
I have yet to find a definite answer to this, but my guess is it measures in foot candles. I have found that it is quite useless. Now if you can find a cheap PAR meter, then you are in business. PAR is the only proper way to guage your lights, despite popular beliefs.
 

Kriegs

Well-Known Member
Peeps... It's a multi-meter, and one of the meters is light... geez.

Your light at canopy level of your plant should peg that sucker out of the park. Take the thing out and point it toward the sun right at sunset when it's just about dark -- it'll peg that thing so hard you'll hear the needle hit the side of the thing. Now imagine high noon... Doesn't matter really what the "actual number" or the units are.. "pegged" is good. Anything less is borderline.

"500" is like dark shade.
 

quantum

Well-Known Member
Here is the actual tester

on a 400 mh it pegs out only under center of brand new bulb.

1000 is the average reading.
comparable to an overcast day.

An early winter sun will peg it out yes
A 1000w mh will too, but not very far from the bulb.

more in the range of 750 to 1500

i was hoping someone who was farmilliar with the tester and its readings might have some input
 

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Kriegs

Well-Known Member
I have virtually the same tester. I used to use it all the time when my plants were smaller -- the meter helped me keep them under the max possible light. Now that they're grown up, some part of them is always on the dark margin no matter how I position them, so I don't use it as much.

Running 400W MH, my tester pegged at about 12" from the light... how old is your bulb? My plants on the outer edges were getting 12-1500 whatevers (it probably is foot-candles.. it sure isn't Kelvins); plants dead-center under the light were getting "pegged" levels. I rotated plants daily to compensate for this.

When I switched to HPS, there was a definite increase in intensity measured by the meter.. consistent with lumen ratings, manufacturer reports, but also suggests that these cheap meters are especially sensitive to red-spectrum lighting (same as winter / sunset sun..).

I wouldn't go too far on the data provided by a $5-10 meter, but it did help this indoor newbie (to MJ.. been gardening for decades) appreciate just how quickly and totally artificial light dissipates from the source.
 
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