Is my reef lighting strong enough?
Check reef lighting by coral goal, PAR target, and footprint coverage instead of picking a fixture from tank gallons alone.
Your reef light is strong enough only if it covers the tank footprint and reaches the PAR range your coral goal needs. ReefCrafter checks both: coverage area against the tank footprint, then PAR at 18 inches against soft coral, mixed reef, or SPS-dominant targets.
Quick check
- 1Measure tank length and width to get footprint area.
- 2Check the fixture's stated coverage at reef depth, not freshwater or fish-only coverage.
- 3Match PAR to the coral goal: soft coral, mixed reef, or SPS dominant.
- 4Use multiple fixtures or bars when one light creates dark edges.
- 5Plan coral placement around measured or expected PAR zones.
ReefCrafter math
Two checks matter more than the fixture name
Reef lighting is not just brightness. A premium fixture can still be wrong if it leaves the edges dark, and a budget fixture can be fine for a shallow soft-coral tank. ReefCrafter separates strength from spread so the recommendation follows the tank and the animals.
PAR target by reef goal
Soft corals can live in lower light. Mixed reefs need enough energy for LPS and some easier SPS near the top. SPS-dominant systems need high and even light, which is why two smaller fixtures often beat one large center-mounted fixture.
- Soft coral: ReefCrafter floor is 50 PAR at 18 inches.
- Mixed reef: ReefCrafter floor is 150 PAR at 18 inches.
- SPS dominant: ReefCrafter floor is 250 PAR at 18 inches.
- Coverage still matters even when the center PAR number looks good.
Why coverage can fail before PAR fails
A fixture might hit a strong center reading while the outer rockwork stays dim. That is why ReefCrafter has a geometric coverage floor: if the listed coverage area is under half the tank footprint, the build gets a hard blocker rather than a soft warning.
Common mistakes
- Buying by tank gallons instead of footprint.
- Assuming one center light evenly covers a 4 foot tank.
- Planning SPS everywhere without checking edge and lower-rock PAR.
- Turning a light to 100 percent immediately on a new tank.
- Ignoring shadowing from rockwork and coral growth.
Buying/spec checklist
- Coverage area equals or exceeds tank length x width.
- PAR target matches the coral plan at realistic depth.
- Mounting height works with your room, lid, and spill preference.
- Control app and schedule are tolerable enough that you will use them.
- Expansion path exists if you later move from LPS to SPS.
ReefCrafter may earn a commission when vendor links are used. The check comes first: recommendations should follow the build requirements, not the affiliate program.
FAQ
Can soft corals grow under cheap lights?
Often yes, especially in shallow tanks, but the light still has to cover the coral zones. Cheap is less important than usable PAR, coverage, spectrum, mounting, and reliability.
Do I need a PAR meter?
You can start with manufacturer data and conservative placement, but a PAR meter rental is the best way to remove doubt once expensive corals enter the plan.
Why does ReefCrafter warn on one light for SPS?
SPS-dominant tanks usually benefit from even spread. One intense light can create a bright center and shaded edges, while two fixtures spaced apart often produce a more useful field.