Arcadia 12% vs 14% Discrepancy Issue

Don Piano

New member
Beardie name(s)
Hey all, I'm new here but I've relied on this forum and its resources for a while in preparation of getting my own dragon. I'm having a bit of an issue that is probably simply just faulty bulbs but I figured it's best to ask.

I've been using an Arcadia 34" 12% Desert bulb in a 36" Arcadia reflector since I first got my dragon and it's been working fine. I do have it on a mesh even if suspending it with zipties wouldn't be much of an issue, but I really don't want to open a hole into the side of my enclosure or a big hole in my mesh to make room for the cord if I can avoid it. It's a wide hole mesh that allows 77% UVB anyway, which I've checked with math and it seems to check out as accurate.

The problem comes from wanting to upgrade to the 14% to just allow for more basking options at lower elevations (he favors a branch that sits about 10-11 inches high for basking, 4-6 UVI), so I procured a 22" inch Dragon bulb and a 24" Arcadia fixture. Measuring the two, however, suggests they're both operating more or less the same. The following are measurements from bulb to dragon for respective lights (all tests done without mesh):

14-15"= 6 UVI
19-20" = 4 UVI
23" = 3 UVI
These results seem to fall somewhat close to what I should expect according to this guide:

14% in Arcadia fixture:
15-16" = 6 UVI
19-20" = 4 UVI
23" = 3 UVI

14% in a Reptisun fixture (just to make sure it wasn't a fixture issue):
13-14" = 6 UVI
17-18" = 4 UVI

I even tested this with another 14% bulb (both from Petsmart) and it came up with more or less the same measurements. It just seems the results are too... identical. The simplest answer is that it could just be both bulbs (the boxes weren't exactly pristine) could have been weak, but I figured it's best to check with you all before I shell out more money for more bulbs. Even in a 36" fixture the 12% should not match a 14% in intensity, should it? I figured it wouldn't make a difference.

I really appreciate any insight on this.
Last edited:

Claudiusx Sicko
Staff member
Not sure what to tell you, I've used both 12 and 14% and have been able to measure a noticeable difference between the two.

Did you check the bulb itself to make sure it's marked as a 14%, and not for whatever reason a 12% in a 14% box?

Did you let both bulbs warm up for 10 or so minutes before taking your measurements? The 14% has a noticeable jump in UVI as it continues to warm up after being turned on.


Don Piano

New member
Original Poster
Beardie name(s)
Yep, the bulbs are labeled as they should be, and I allowed the new one (the 14%) time to warm up before taking a measurement. Doesn't seem to make a difference. and they're both returning practically identical results. I guess it could be mislabeling or some internal issue with the bulb. Either way, the strength is definitely not there after all this.

At this point I think it's probably easier to just bite the bullet and drill a hole and insert a grommet to funnel the cable. That way I can just zip tie it to the screen already and stop worrying about UV bulbs for a year, ha ha.

Thank you, Brandon. Just gonna chalk it up to bad luck and get on with it.

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