[GothicGroucho]

I have a 20-long planted aquarium. My lighting setup is a little bit unusual in that I use a 48-inch grow light fixture, which extends beyond the sides of the tank and illuminates some houseplants in addition to my aquarium (see photo).

The fixture holds only a single T5HO, but I wonder if I could take more advantage of the CO2 I use by increasing to either a two-T5HO or a four-T5HO fixture. I want to continue to use this sort of "grow light" set up, where the height of the fixture is adjustable; I don't want to freak my fish out with too much light.

Without bring LEDs into the discussion (which I realize is also an option), I wanted to ask whether two T5HOs or four T5HOs would be better for me.

Thanks!

 

[minorhero]

From the picture it looks like you have a large mass of plants floating. You could dramatically (probably double to quadruple) the light hitting your substrate by removing or at least pairing down that plant mass.

The more light you add the more co2 and fertilizer is needed to maintain balance. You may already have excess of both of those with your current light or it could be just enough or not enough etc (don't have enough information to say). What is certain is that the more light you add the quicker things can go wrong if mistakes are made. So yes, you can definitely add more light. But just keep a very close eye on your plants if you do so you can see if its too much for your ferts/co2.

I wouldn't worry about bright light freaking out your fish. In the wild they deal with the sun which is dozens of times brighter then two T5 bulbs.

 

[GothicGroucho]

From the picture it looks like you have a large mass of plants floating. You could dramatically (probably double to quadruple) the light hitting your substrate by removing or at least pairing down that plant mass.

The more light you add the more co2 and fertilizer is needed to maintain balance. You may already have excess of both of those with your current light or it could be just enough or not enough etc (don't have enough information to say). What is certain is that the more light you add the quicker things can go wrong if mistakes are made. So yes, you can definitely add more light. But just keep a very close eye on your plants if you do so you can see if its too much for your ferts/co2.

I wouldn't worry about bright light freaking out your fish. In the wild they deal with the sun which is dozens of times brighter then two T5 bulbs.

Thanks; good point about the floating plants. I do like the way they look, and I think they make a good nutrient sponge, but I certainly could reduce them. I do, periodically, but they grow like crazy!

I'll keep thinking about the light. I wonder if, at least, with two T5HOs I'd get a wider spread and see less tropism in my stem plants.

 

[minorhero]

Thanks; good point about the floating plants. I do like the way they look, and I think they make a good nutrient sponge, but I certainly could reduce them. I do, periodically, but they grow like crazy!

I'll keep thinking about the light. I wonder if, at least, with two T5HOs I'd get a wider spread and see less tropism in my stem plants.

You will definitely have wider spread with more light sources. Whether it doe what you want will probably depend on placement. If it's a double fixture with bulbs close together will have less of a wider spread then two single bulb fixtures placed far apart or a quad fixture with only 2 bulbs placed apart from each other. /Shrug lots of variables, that's part of the fun