Aquarium Lighting, Lumens/Watts?

[SkittleKittie]

My husband and I stumbled into being marine aquarists. For a while they survived, but now we've learned a lot more and managed to stabilize our tank. We are by no means experts, which we learned is exactly what a 20gal tank is for. So, we're upgrading!! (I also needed more room for more fish )

So far the most confusing thing has been the lights. We've been searching all over for the appropriate lights for the tank we're building (75gal) and I think we've been making this way more difficult than it needs to be. Our current set up is just 2 clowns and some pests so not much light requirement, but we'd like to be prepared to add anemones and more fish in the bigger tank.

Firstly, Is there a difference in the light requirement for a tank with just anemones vs. a reef tank which presumably has soft and hard corals?

We found some recommended watts per gallon but being unsure of the conversion between LED power wattage and actual light output wattage... the numbers were coming up weird. Overthinking this?

TLDR; Our LFS recommended a 64hd and we just want to verify if this is enough/ too much or if it's perfect for our 75gal anemone/fish tank (no hard corals)?

 

[Biokabe]

First off, welcome and congratulations on making it far enough to need an upgrade. =) Most people who dip their toes into saltwater don't make it that far, so you're already doing good.

When it comes to keeping a reef tank, especially with modern LEDs, throw the idea of watts per gallon out the window. It's an old rule that comes from freshwater planted tanks when lighting options were limited (and thus most people had the same things), and it doesn't really translate to much of anything anymore.

In terms of lighting your tank, it all depends on your dimensions and what you want to keep. If you mostly want to keep anemones in your tank, you might be able to get away with some fairly conservative lighting. Is your 75g a cube or a traditional rectangle?

If it's more of a cube shape, then the Hydra 64HD would probably give you a pretty good solution for anemone-only or less light-intensive corals. You'd need to keep things up a little higher in the tank, and your anemones would probably need regular supplemental feedings.

If it's a rectangle, I'd recommend a pair of Hydra 32HDs instead of the 64. That lets you split your light up a little more to get a better spread of light throughout the tank rather than concentrating everything in the center.

If you want to step up to more demanding corals down the road, you can either simply add more fixtures - probably 3-4 32 HD over a rectangular - or pick up one of the hybrid fixtures.

You can also use T5 fixtures or metal halides. I couldn't begin to make a recommendation for halides, but a 4-bulb T5 fixture (sized for your tank) would be good for low-light corals, a six-bulb fixture would work for somewhat more demanding, and an 8-bulb fixture would be good for pretty much anything, at least insofar as lighting is concerned.