New Member
Jan 13, 2019
Hello All!

I apologize in advance, I'm not sure if this is the right spot for this question, but it seemed like the best fit!

I'm starting to plan out my second tank, a 10 gallon that I'm hoping to put in a part of my house that gets a lot of natural light. My other tank (a 40b) is a room that gets essentially no natural light, so this is totally uncharted territory for me. I've heard that natural light can be a challenge for keeping tanks, but I was hoping that some of you plant experts might have tips or resources to get me started.

I'm thinking that I'll likely want a light with adjustable levels, since I likely won't need as much extra light as just a "normal" setting, but that is sort of as far as I've gotten. What would you all do? Any light suggestions? Things to watch out for?


Aug 12, 2017
Are you talking about natural ambient light in a bright room, or natural sunlight filtered through a window? These are two different lights with different outcomes.

Bright room ambient light does not eliminate the need to use artificial light, and light management to grow plants is essentially the same. Direct sunlight is different and much more intense than even the highest artificial light. Even though glass plane can filter out 50% or more direct sunlight, I can still measure over 300 PAR at the window or a great distance away from the window. While artificial light diminishes by inverse square law away from the light source, natural sunlight rays are straightly parallel with no diminishing effect with distance.

I have two shrimp bowls hanged by a window that receive several hours direct sunlight. My set up is no tech, all natural. With no supplemental CO2, direct sunlight can strip off CO2 to near zero at peak sunlight period as manefested by huge swing of pH, and submerged plants grow very slowly. Floating plants grow fast though as they receive aerial CO2, and carpet plants grew fast initially and slowed down due to exhaust of nutrients in dirt. I have no algae problem except for filamentous apirogyra. If you have heavier bio load, you may have to deal with green water as I have it in my outdoor water tub to feed daphnia.
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Lifetime Member
Lifetime Member
Jul 13, 2017
Arnold, MD
Even though glass plane can filter out 50% or more direct sunlight, I can still measure over 300 PAR at the window or a great distance away from the window.

My 80G gets a 20 minute dash of sunshine through a slightly dirty basement window.
It registers over 600 PAR.

Tim Harrison

Lifetime Member
Lifetime Member
Jul 7, 2017
Really depends on a few factors. Placing a tank next to a window that does not receive direct sunlight or perhaps gets it early or later in the day when it's not so strong can work well, take a look at The Banyan Forest Journal. If the sunlight is too strong you will run in to algae problems. Blue green algae (Cyanobacteria) love direct sunlight, and will happily grow between the glass and the substrate, for instance.
A good nutritious substrate will help as well, especially if you are going low-energy. ADA AS will work well, or you could go with dirt, which has the benefit of releasing some CO2 as it mineralises.
The other factor is plant choice. Low light plants are obviously going to suit a natural light tank the best; Crypts, ferns, anubias, buces, moss etc. Take a look at Tropica's "Easy Plant" list for more ideas.
As for light, I'd go with an RGB LED unit. They have fantastic colour rendition which make your plants and critters pop. But whatever light you buy make sure the intensity is adjustable; buy one with a dimmer or a control unit, or a light that can be retrofitted with one.