Lighting on 75 gal

Hi Judyok,

Your tank is about 21" tall and I am assuming approximately 2" of substrate means 19" from the aquarium top to the substrate; then we add 3" for the height above the tank so you are looking at approximately 22" from the light to the substrate. Let's assume that your fixture is equivalent to the Fishneedit fixture. Based upon Hoppy's chart the estimated PAR value would be 26.

Per fixture

If you run both fixtures, you're in the high light range.

Odyssea fixtures give more PAR than either FishNeedIt or Coralife, so you get about 40 micromols at 22 inches, which is low medium light. Roy, that chart includes the Odyssea light now too.

If you run both fixtures, but keep 8 inches or so between them you probably still have about 40 micromols, but over much more of the substrate. The PAR only doubles if the fixtures are very close together, for maximum overlap of their light.

Hmmm...looking to get closer to the high light range. I've seen alot of praise for the Catalina lights. What could I get that would distribute light evenly in the high light range. I will be receiving a pressurized co2 system next week and I wanted to try to grow some stems plants and a few others that require high light, I also have my dry ferts for dosing. I am, of course trying to achieve this with a minimum of algae.

Check out this light. Honestly it is probably too high of light for the 75 without having to raise it quite a bit. I have the four bulb Oddysea over my 75 and I still raise it almost eight inches off the top. It suits my needs.

I also have the 24" 2 bulb version of the link I posted and it is amazing. The reflectors are absolutely superb.

Higher Thinking, I don't see a link.

http://www.amazon.com/Commercial-Tube-Fixture-Light-Size/dp/B002TJOGLE/ref=pd_sim_lg_3
I suppose it would help if I posted the link

It doesn't say that it is HO, but they are.

I read somewhere on the forum about the Hydrofarm lights being of good quality and that light is a good price. It may be too high of light, but it also can be suspended a bit higher off the tank. I like the idea of the Catalina 3 bulb light have to separate cords and switches so I could run 2 of the lights if I wanted. Would that light be sufficient to provide high light?

Judyok said:

I read somewhere on the forum about the Hydrofarm lights being of good quality and that light is a good price. It may be too high of light, but it also can be suspended a bit higher off the tank. I like the idea of the Catalina 3 bulb light have to separate cords and switches so I could run 2 of the lights if I wanted. Would that light be sufficient to provide high light?

Click to expand...

With all 3 bulbs on, and the light sitting on top of the tank, you should get around 70 micromols of PAR, which is high light, in my opinion. If you ran just the outer two bulbs I'm not sure how much PAR you would get, probably between 35-50 micromols.

Thank you all for the specific information.