UV needs and bulb questions

I've been searching around to look at all the best UV bulb options that are available now and there are two that stand out to me most.

Arcadia desert t5 12% & 14% (curious what people think of the difference? I'm currently using the 14% bulb)
Megaray MVB (thinking about getting the 70w bulb for my setup, my arcadia bulb is about 6 months old)

Now that its warmer here in Oregon, I've been able to give my boy Malachi outdoor time. I am curious how many hours of natural sunlight would actually replace a artificial UV bulb on a partial shady day and a sunny day. I've seen varying amounts of time for this and the posts are a couple years old. Not sure if there's new knowledge out there for it now or not but I am interested. I tend to look at the weather UV index and take my dragon out between 6-8 UV index days. He's always leashed, protected, watched and provided shelter from the sun if he so desires.

The 14% is a really strong bulb, I only recommend them for large and tall enclosures. I don’t like MVB as much, they don’t have a nice wide coverage area and have poor color quality. Plus you have to control heat separately. If you have a good setup for t5 lights, stick wit that. That Arcadia will last you a while. Mine is a year and a half old I think, and still strong enough (I have a uv meter) that I havn’t had to adjust the distance. I expect to get a good 2-3 years out of it, adjusting the distance as it gets weaker.

As for light “dose”... A certain wavelength of UV is ideal for D3 generation, the UV index pretty closely tracks with that, so if you go outside with a UVIndex of 6 or sit under an Arcadia 14% (About 12-14’ away is a UVI of 6) it’s going to be the same dose. Sitting under a weaker lamp would take longer, just like it takes longer to get sunburned on a cloudy day.

The old 30 mins in the sun.... has never been very accurate... but also does fro using much weaker bulbs like the T8s

I'm curious if people have found any noticeable difference in decay for the 12% & 14% Arcadia bulbs. Also am curious, for those with Solarmeters, how long their Arcadia bulbs have lasted them and what their bulbs are reading per distance over time? Would love to hear more about that from other Arcadia users with Solarmeters as well.

I haven't used Megaray MVBs before. Only Powersun MVBs many years ago. I'm actually using a couple really old Powersun MVBs as a means of heating the tank and one has finally gone dead on me (Perfect timing as the weather is heating up anyway lol). I expect my Arcadia bulb to last a year or more but I don't have a Solarmeter to track it and I normally buy a bulb every 6 months anyway so I figure why not get a MVB this time since my Arcadia bulb is more than likely still good. I've read a lot of positive reviews on the Megarays MVBs, aside from the difference of fluorescent and MVB bulbs, what do you think of the Megarays?

As for replacing artificial UV with natural sunlight, it really makes me wish I owned a Solarmeter to test my bulbs and the sunlight I get on my back porch so I could see the differences in UVB output. Since the exposure is more consistent with UVB bulbs, allowing the animal to regulate itself for D3 synthesis as much as it needs throughout those 14 hours of daily artificial exposure, it's a no brainer to use UVB bulbs and use the sun as supplementation/enrichment whenever you can (unless you live in a place you can keep your beardies housed outdoors). Wish I knew exactly how much and how often beardies needed UVB. Science is fun and would be great to know you're taking care of them perfectly!

I haven't tried the 14% bulbs but I have a 12% that I got in July 2014 that is still going strong. I read UVI around 4 in the basking area. I also have two MegaRay 100w bulbs that I use as portable basking spots. They last quite a long time (a year and a half for my first one) but they have a very intense narrow beam of UVB. My dragon tends to sit off to the side of the most intense UVB in the center and gets what he needs (at around 4-5 UVI vs 3x that in the center). The PowerSuns have a wider beam which I like but I haven't tested them extensively yet.

I have only had the one Arcadia but I think a year+ is very typical for them. Mine is still UV 6 at 12” away.

Mega Ray is a reliable brand. If I got an MVB I would probably go with them. That said, MVB would not be an upgrade from T5, really.

Honestly, a solar meter is a pretty handy investment. If, like cooper is seeing, the lamps last 4 years or so with good output it will pay for itself rather than buying bulbs every six months.

I agree that an MVB isn't a good replacement for a T5 in the main enclosure. It can't top the nice even wide spread of a T5 and the independent heat control that allows. I've found them very handy for portable lights and for travel though. I'd prioritize having a T5 but if there is spare money in the budget then adding some MVBs to the mix is nice.