Lighting rules

[nfinit1]

Hi All
What is the formula for lighting??
Is it 1.5 watts per gal??
Or is it 2.5 per gal??

I hahve a 75 gal oceanic
Coral Sea life BriteLite.with 2x96 or 55..I think it has 10,000 k bulbs in it

[Leopardess]

Well firstly there isn't a "formula" for lighting. It depends on what plants you want to grow.

Based on the two options you gave, 2.5 is a much better one. That is generally an acceptable level.

Also, for a planted tank, usually 5500-6700k is considered what to shoot for...

[carpguy]

Like Leopardess said, there isn't a one answer rule of thumb. It depends on what kind of plants you want to grow and what kind of setup you want to have.

As a rough guide:
Under 1 wpg is just too little in general.

1-2 wpg is low light. You can keep lowlight plants and can skip supplemental carbon. The growth will be slow and ambient CO2 levels can keep up, although supplementing them can be beneficial. There's lots of good info on keeping low light tanks on the boards. Try a search. Plantbrain has outlined a specific regimen on a number of occasions.

2-3 is medium light. You can grow more types of plants and growth will be more rapid. As the light levels increase, maintenance also increases. Trimming, pruning, dealing with fertilizers. Somewhere in this range is that line where CO2 becomes a non-optional thing. DIY (for a 75, a lot of maintenance and a lot of sugar -- long-term costs are not insignificant), pressurized (easy, steady, and economical after that initial investment), or Excel (likely to get expensive on a 75).

3-4 is high light. Still more plants available. Some plants that are happy to grow under lower light levels will show better color as light levels increase. Stuff like that. Serious maintenance of fert levels and CO2 a must. Your driving fast now and even a little inattention can spell disaster. The algae spores are in the air and they are waiting for their opportunity.

4+ is really friggin bright. Get shades for yourself, and for the fish.

Depth increases light requirements somewhat. Very small tanks need more light and very large ones somewhat less. The rough guide is for roughly "normal" sized tanks. Coverage is also an issue: if your tank is 18" wide (front to back) you'll want to make sure the lightbanks have a bit of spread over that range.

10000k bulbs are a bluer reef light. As Leopardess also mentioned, 5000-6700k are generally considered more appropriate for plants. The bluer bulbs will work, but not as efficiently and they may alter the growth patterns of the plants (making them leggier and more drawn out? I don't remember…).

2 banks of 2x55w CF would give you almost 3 wpg, which I think would be a nice high medium light tank. I bank would be low and that's low directly below it — low and 6, 7, 8 inches off to the side and its lower again. Inefficient bulbs and its lower again.

With that much light there can be a lot of spillover into the room without a fully enclosed canopy. Closing it up means that the area above and around the tank can stay dark and the focus can really be on the area you want lit up. But thats aesthetic type stuff…

HTH :cool: