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Most planted tank LEDs make you choose: enough power to grow plants, or enough automation to stop babysitting your light schedule. The Finnex Planted+ 24/7 HLC is one of the few fixtures that actually delivers on both — strong PAR output for real plant growth and a fully programmable day/night cycle you only set up once.
This review breaks down what the HLC does well, where it falls short, and whether it’s the right light for your planted tank.
Design and Build Quality
The HLC’s single-cast aluminum hood is the thinnest fixture Finnex makes — just 0.23 inches at the center. It looks clean sitting on a tank, handles heat well, and holds up against the humidity above an open-top aquarium. Finnex themselves have said they wish they could fit the CRV’s specs into this hood. That tells you how much they like the form factor.
The fixture uses a four-bulb LED cluster with 8,000K daylight whites, reds, blues, and greens. Each color channel is independently adjustable on a 0–10 scale, which gives you a wide range of brightness and color options. Dialing the white channel up or down is where you get real control over plant growth intensity.
It comes in five sizes — 20, 24, 30, 36, and 48 inches. The clear mounting legs are adjustable and have a removable inner section: keep it in for a U-shape that straddles rimless glass, or pop it out for an L-bracket that sits on thicker rims. Functional, though the plastic legs feel a bit loose on some setups.
The 24/7 Automated Cycle
The 24/7 mode runs a full sunrise-to-sunset-to-moonlight cycle that repeats daily without any input from you. The default ramps from a cool dim dawn through a warm sunrise, peaks at an intense midday, fades into a reddish sunset, and finishes with a blue moonlight phase.
Where the HLC improves on earlier Finnex 24/7 models: you can customize the colors and intensities within the cycle. The original Planted+ 24/7 locked you into factory colors during automated mode. With the HLC, you set your preferred color and brightness at each three-hour interval, and the fixture ramps smoothly between them. Set it once, and it just runs.
The IR remote also gives you four weather simulation modes — cloudy, thunderstorm, sunny, and moonlit night — plus four memory slots for saving custom color combinations. These only work outside of the 24/7 cycle though. Getting in and out of 24/7 mode requires a specific button sequence that takes some getting used to, so keep the manual handy at first.
PAR Output and Plant Growth
This is where the HLC genuinely surprised people. Independent PAR testing measured it at roughly 155 PAR at 5 inches below the waterline and around 127 PAR at 9.5 inches — at max settings. For reference, the older 24/7 SE topped out around 85 PAR at that same depth. The HLC is the most intense planted fixture Finnex has made.
That’s more than enough output for a high-tech setup with CO2 and fertilizer dosing. For low-tech tanks, you need to dial it back. Halving all channels drops PAR from around 127 to roughly 60 at 9.5 inches — still plenty for most easy and moderate plants without CO2.
One thing to know: the HLC doesn’t use true 660nm red LEDs. Only the CRV and ALC in the Finnex lineup have those. The 660nm wavelength is the sweet spot for photosynthesis, and it’s the CRV’s main selling point. However, spectral analysis has shown the HLC’s red output looks very similar in practice — and the HLC’s higher overall PAR likely matters more for growth than the marginal wavelength advantage.
The Remote Problem
The IR remote is how you control everything — the 24/7 cycle, color adjustments, weather modes, memory slots. It works well and the buttons are clearly labeled. The problem is that there are zero manual controls on the fixture itself. If the remote dies, you’re locked into whatever the last setting was with no way to change it.
This is the biggest single drawback of the HLC, and it shows up repeatedly in user complaints. Keep the remote away from water, store it somewhere consistent, and have a spare battery on hand. It’s also easy to accidentally overwrite saved memory slots while tinkering — the save and switch buttons are close together, so go slow during initial setup.
Pros and Cons
Pros
- Highest PAR output in the Finnex planted lineup — handles low through high-light plants
- Fully customizable 24/7 cycle with adjustable color and intensity at each time slot
- Razor-thin aluminum hood looks great and manages heat well
- Less expensive than the CRV while outperforming it on raw output
- Works on both rimmed and rimless tanks
Cons
- No manual controls on the fixture — remote failure means total loss of control
- No onboard clock makes initial 24/7 programming confusing
- Short power cord is a problem on tall stands
- Powerful enough to cause algae fast if intensity isn’t managed on low-tech tanks
FAQ
Can the Finnex HLC grow carpeting plants?
At full intensity in tanks under 18 inches deep, yes — but carpeting plants like Monte Carlo or dwarf hairgrass also need CO2 and proper fertilization. The HLC has more than enough PAR; the light won’t be your bottleneck.
What’s the difference between the HLC, CRV, and KLC?
All three share the same 24/7 automation. The HLC has the thinnest design, highest PAR, and lowest price. The CRV adds true 660nm red LEDs but costs more and sits in a wider hood. For most planted tanks, the HLC is the best value.
Will this light cause algae?
Any powerful light can if intensity and photoperiod aren’t balanced with nutrients and CO2. Running the HLC at full blast on a low-tech tank will almost certainly cause problems. Dial intensity to about 50% without CO2 — that still gives you around 60 PAR at 9.5 inches, which is plenty for easy and moderate plants.
Final Thoughts
The Finnex Planted+ 24/7 HLC hits the right balance for most planted tank keepers. Strong enough to grow demanding plants, automated enough to genuinely set and forget, and priced below most of its direct competition — including other lights in Finnex’s own lineup. The slim aluminum build is a bonus that makes it look right at home on a well-scaped tank.
The real tradeoff is the complete dependence on the IR remote. No manual fallback is a design choice that keeps the fixture slim and affordable, but it’s a risk you’re accepting. For what you get at this price point, I think it’s worth it — just take care of that remote.
