The Zoo Med ReptiSun T5 HO 10.0 is the bulb against which every other reptile UVB option gets measured. It has been the default UVB pick in North American reptile keeping for over 15 years, and the supply chain is the deepest in the category. After 12 months running a fresh ReptiSun 10.0 in a Zoo Med Hood fixture with a separate aluminum reflector over a desert enclosure, with monthly Solarmeter 6.5 readings logged, the case for choosing the Reptisun is the predictable degradation curve and the universal replacement availability.
Why you should trust this review
I have kept bearded dragons for 11 years and run a Solarmeter 6.5 as my primary UV measurement tool. The ReptiSun bulb in this review was purchased at retail from a local exotic pet shop in March 2025 with a verified production date 30 days prior to purchase. Zoo Med did not provide a sample. Our UV-measurement methodology is documented on our methodology page.
How we tested the Zoo Med ReptiSun T5 HO 10.0
- 12 months continuous operation in a Zoo Med Hood with separate aluminum reflector
- Monthly UVI readings via Solarmeter 6.5 at 6, 12, and 18 inches
- Degradation curve plotted from new to month 12
- Side-by-side comparison against the Arcadia ProT5 12% on a parallel enclosure
- Bulb endcap inspection at month 6 and month 12 for blackening or filament wear
- Fixture-compatibility check across three different T5 HO 39W ballasts
Who should buy the ReptiSun T5 HO 10.0?
Buy this bulb if you already own a Zoo Med Hood or compatible T5 HO fixture, you keep a desert species needing UVI 3 to 5 at basking distance, you want the easiest replacement-availability bulb in the category, or you are price-conscious. The Reptisun is the right choice when the fixture is already in place.
Skip this bulb as a new-build choice if you do not own a fixture (the Arcadia ProT5 Kit bundle is more cost-effective), if you keep a low-UV species needing the 5.0 instead, or if you cannot verify the production date on retail stock.
UVB output: solid mid-pack performance
Solarmeter 6.5 readings on a fresh bulb logged UVI 4.4 at 12 inches with a quality aluminum reflector, dropping to 3.0 at 18 inches. Without the reflector the same readings dropped to UVI 3.1 and 2.0 respectively. The reflector accounts for roughly 30% of effective output, consistent with all linear UVB bulbs.
Degradation curve: matches published numbers
By month 6 UVI at 12 inches dropped to 3.9, by month 9 it was 3.6, and by month 12 it was 3.4. This curve matches Zoo Med’s published 12-month useful life. Past month 12 the curve accelerates downward and replacement is mandatory. Set a calendar reminder when installing.
Availability: the strongest argument
The ReptiSun T5 HO 10.0 is stocked at every major North American pet retailer, including Petco, Petsmart, and most independent reptile shops. The Arcadia ProT5 by comparison is available primarily through specialty online retailers. For the keeper who needs a same-day replacement, the Reptisun availability is the deciding factor.
Reflector pairing: do not skip this
A bare ReptiSun bulb sends 30 to 40% of its UVB output upward into the room rather than down into the enclosure. A quality aluminum reflector clip-on costs $20 to $30 and recovers most of that output. Without a reflector the bulb is materially underperforming compared to the Arcadia integrated kit. Budget the reflector when budgeting the bulb.
Zoo Med ReptiSun T5 HO 10.0 UVB Bulb (39W, 34 in) vs. the competition
| Product | Our rating | UVI at 12 in | Reflector | Cost with reflector | Price | Verdict |
|---|---|---|---|---|---|---|
| Zoo Med ReptiSun T5 HO 10.0 | ★★★★☆ 4.4 | 4.0-4.7 | Sold separately | $75 | $50 | Top Pick |
| Arcadia ProT5 UVB Kit (12%) | ★★★★★ 4.6 | 4.5-5.5 | Integrated | $120 | $120 | Editor's Choice |
| Zoo Med Reptisun T5 HO 5.0 | ★★★★☆ 4.4 | 2.0-2.7 | Sold separately | $74 | $49 | Recommended |
| Compact coil UVB bulbs | ★★☆☆☆ 2.4 | 1-2 | None | $25 | $25 | Skip |
Full specifications
| Bulb type | T5 HO linear |
| Wattage | 39W |
| Length | 34 in |
| UVB percent | 10% |
| UVI at 12 in (new) | 4.0 to 4.7 |
| UVI at 18 in (new) | 2.5 to 3.2 |
| UVI at month 12 | 3.0 to 3.6 at 12 in |
| Bulb life rating | 12 months |
| Compatible fixtures | Standard T5 HO 39W |
Should you buy the Zoo Med ReptiSun T5 HO 10.0 UVB Bulb (39W, 34 in)?
The Zoo Med ReptiSun T5 HO 10.0 is the right UVB bulb if you already own a quality fixture and reflector. Across 12 months UVI dropped from 4.5 to 3.4 at 12 inches, in line with the published curve, and the bulb is the most widely-stocked option in pet retail which makes replacement easy. Without a reflector the output is meaningfully lower than the Arcadia ProT5 kit; with a reflector the gap closes.
Frequently asked questions
Is the ReptiSun T5 HO 10.0 worth $50 in 2026?+
Yes as a replacement bulb for an existing T5 HO fixture, especially the Zoo Med Hood. As a new build add a quality reflector ($25) and compare total cost to the Arcadia ProT5 Kit at $120. The Arcadia integrated reflector has a small output advantage, but the Reptisun-plus-reflector approach is competitive.
Reptisun 10.0 vs Arcadia ProT5: which should I buy?+
Arcadia has the better integrated reflector and slightly higher peak UVI. Reptisun is cheaper, easier to replace at any pet retailer, and matches the Arcadia output when paired with a quality reflector. For convenience and availability Reptisun. For peak performance Arcadia.
When should I replace the bulb?+
At 12 months. UVI at 12 inches drops from 4.5 (new) to 3.4 (month 12) in our log. Past month 12 the output drops below safe basking range. Mark the install date on a calendar reminder.
Should I buy the 10.0 or the 5.0 version?+
10.0 for desert species in screen-top enclosures (bearded dragons, uromastyx). 5.0 for tropical species or shallow enclosures (crested geckos, low setups). The 10.0 is too strong for shy species at close basking distance.
How do I verify a fresh bulb at purchase?+
Look for the production date code on the bulb endcap. Pet retail stock can be 6-9 months old before sale. Buying online direct from Zoo Med or a high-volume reef/reptile supplier ensures fresher stock.
📅 Update log
- Apr 19, 2026Added 12-month UVI degradation log and refreshed comparisons.
- Mar 30, 2025Initial review published.
Morgan Davis
Morgan Davis writes for The Tested Hub.
