Nano issues: substrate bubbles, duckweed - The Planted Tank Forum
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post #1 of 7 (permalink) Old 10-20-2012, 09:24 PM Thread Starter
Join Date: Oct 2012
Location: Pennsylvania
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Nano issues: substrate bubbles, duckweed

Hello all!

I have a natural / "Walstad" style five gallon hex at work, my first planted tank, and it's doing great! There are two minor, quibbling issues I was hoping to get advice on.

First of all: the substrate is about 1" soil with a 1/2" sand cap. The soil is probably too deep for such a small tank, but there isn't much I can do about it now. There are air bubbles in the soil. Occasionally (when a drawer is closed, or the chair bumps the desk, etc) they're released. They don't seem to be "anaerobic bubbles of death!" yet and don't seem to be doing any harm, but should I be concerned? Is there anything I can do about them, aside from poking at the soil with stick?

Secondly: added duckweed and giant duckweed about a week ago. And they have been steadily dying since.

Based on what little I know about duckweed, I'm thinking there's not enough nutrients (ie: decaying stuff) in the water to support them. This leads to a few other concerns.

A) I added the duckweed in hopes it would cover the surface and help slow the evaporation some. I'm going to cut some plastic to cover the top, but only about 1/2 of it due to emergent plants. Any other suggestions?

B) All the other plants right now have roots. So they can get to that nutrient-rich (air-bubble-filled) soil, no problems. But this does not bode well for any other floating plants I'd like to add. In the long term, I'm wondering if there isn't enough livestock to support the plants (without ferts), but the tank is so small, it's too easy to overstock.

At first I thought the dead duckweed would start to rot and, in turn, feed the surviving duckweed but that doesn't seem to be happening. Also the dead duckweed looks pretty awful.

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post #2 of 7 (permalink) Old 10-20-2012, 10:40 PM
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Duckweed sometimes dies when it gets too much light.
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post #3 of 7 (permalink) Old 10-22-2012, 01:44 AM
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Heat will also kill duckweed, what temp are you running it at? (I have a Sulawesi biotope and the temp killed all my floaters)

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post #4 of 7 (permalink) Old 10-23-2012, 02:47 AM Thread Starter
Join Date: Oct 2012
Location: Pennsylvania
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Thanks for the feedback.

The tank only gets ambient lighting (it's near a window), so that should be okay.

It is pretty warm, like 82 -83... warm enough to cook duckweed?

As an added bonus, apparently pond snails piggybacked in on the duckweed. So, it looks like I'll end up without the plant I wanted and with the snails I didn't want, yay. Fortunately I think the tank is small enough I can stay on top of this easily.

Last edited by jaybird; 10-23-2012 at 03:08 AM. Reason: Additional info
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post #5 of 7 (permalink) Old 10-23-2012, 03:09 AM
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How much flow is there on the surface of the tank? Duckweed hates being tossed around on the surface.

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post #6 of 7 (permalink) Old 10-23-2012, 08:44 PM
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When I kept my tank at 70, I had duckweed clogged across the whole top. I started treating for ich (and increased temp to 80) and most of it has died back. I think it would probably be fine if I had a fan blowing on the surface but then I'd have to crank the heater up again to keep the temp up, and deal with all the extra evap. In fact all my floaters have been significantly melted, water lettuce, frogbit, and salvinia.
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post #7 of 7 (permalink) Old 10-29-2012, 11:41 PM
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I agree, when I tried duckweed on a tank many moons ago - it died on me. I think The water level was too close to the top. I had a glass cover and the light over it. I think it either got too much light or it got too hot as there was little air circulation between the water surface and the cover...
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