# Window light - OK or not OK?



## boomstik (Feb 2, 2015)

Hi forum,
I'm getting lots of conflicting advice from research around the 'net, as well as from my LFS, with regards to putting a tank near a north-facing window.

The tank is a standard 10G, and sits 90º to the window, with is short side near a wall. So the only light it's getting from the window is on its front and top (there's no cover). I'll try to illustrate (view from top):


```
East
        ├┈┈┈┈┈┈┈┈┈┈┈┈┈┤ ⬅︎ east-facing window
      ╦ 
      ║  ┌╍╍╍╍╍╍╍╍╍╍╍╍╍╍╍╍╍┐    ⬅︎ black background blocks light
      ║  │                 │
wall  ║  │      TANK       │
      ║  │                 │
      ║  └─────────────────┘
      ╩         Front
      ┬         
      ┊      ↗↗↗↗   
      ┊     ↗↗↗↗  window light
North ┊    ↗↗↗↗
      ┊
      ┴
```
To expand on these conditions:

- The front and top of the aquarium are getting most light.
- The east-facing window is always in the shade, never gets direct sunlight.
- For the purposes of this exercise, let's assume there is no artificial lighting (in fact there's a little room lighting at night, which we can consider negligible). 
- The front of the tank will get a little *direct* sunlight at dusk in the summer, maybe an hour just before sunset. At all other times, it only gets diffused light.
- There's a 13 watt or so CFL (the cheap kind) i've been turning on every night for about an hour after dark, just while i'm getting this figured out. I'd like to get rid of it, as it's 1) ugly and 2) cheap = low CRI and I assume so is PAR/PUR. Let's ignore it for now, although it may have contributed to my plants' growth so far. (I've only had it for a week, so maybe not).

So what I'm trying to figure out is, being located in downtown Toronto, would these be considered low or medium lighting conditions? I don't imagine this would count as "high". I know window lighting is unpredictable, but the advice I've heard so far has ranged from "No way, this is the worst possible lighting, your plants won't grow" to "This is too much light, you'll get lots of algae". Is there no consensus? Am I a unique snowflake, and does no one else have a planted tank under these conditions?

So far I've got some anubias, java fern, and rotala rotundifolia. They seem happy, I'm seeing a bit of growth on all of them over the last month, and the java fern is making babies. I had a bit of brown algae as the tank was getting established, it's gone now. There's a small canister filter, and the tank is about 60% stocked according to AqAdvisor (neons, cardinals, and a chainlink loach). There's no CO2 injection, though I'm thinking of adding a DIY setup maybe if it's appropriate. My ammonia/nitrite/nitrate levels are all healthy. Water changes 30% weekly. I do not dose any ferts.

I'd really like to add some carpeting moss, but was told that I should forget about it unless I get artificial lighting.

Any thoughts on this from the community?

Thank you!!


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## Rmwbrown (Jan 22, 2009)

I doubt it is enough light. My wife runs a setup in an area with a very similar window configuration with the addition of a LED lighting system. Moreover, I think the Java fern is telling you this. If by "making babies" you mean reproducing itself on the leaves, this is not necessarily a sign of health, but of damaged/dying leaves, or the plant trying to get the hell out of wherever it is at by making itself mobile. 

You don't need to go crazy or spend a fortune to grow these plants, but you will need a cheap aquarium light and then some DIY Co2 to keep BBA off the Anubias.


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## default (May 28, 2011)

I agree with the post above.

Take a few shots of your tank so we can see what the plants look like right now. You would most likely need a few weeks-months to see any change in those plants - except the Rotala. I've had Anubias, Ferns, and Bolbitis survive in pure indirect sunlight for months(~6), but your Rotala will show light deficiencies much sooner.

Another concern may not be just the light, but also the effect on the temperature, especially for such a small tank.


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## boomstik (Feb 2, 2015)

Thanks everyone for the replies. Looks like I'll have to watch the tank closely for any changes, but not mess with it too much. An update so far: I started seeing yellowing and browning of the tips on the anubias leaves closest to the CFL, which brings me to believe it is getting too much light overall and the CFL is pushing that over the limit for the low-light plant. So I'm going to stop the use of the CFL for now altogether.

I am seeing new leaves growing on the Java ferns, at least three on two separate plants. Interesting enough, the new leaves are broader than the old ones - not sure if that's expected with this species. I'm also seeing new growth on the Rotalas, they all look healthy and green and are growing pretty fast. So I'll assume for now that the lighting is at least moderate and somehow magically adequate for my tank, despite the window layout and time of year. I'll see how things change once we start getting more sun. 

Will post pics once i can get some decent shots. One of the challenges of the tank being by the window is that everything is reflecting in it, including yours truly


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## boomstik (Feb 2, 2015)

PS: I realize my reply above goes sort of against what both of you suggested, but the observations are making me want to wait and observe. I'll post updates. Thanks for the insight!


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