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new 65G Walstad tank - with pictures!

5K views 24 replies 6 participants last post by  jochemspek 
#1 ·
Hi all,

I just started my first walstad tank (see picture with the cat lying in anticipation: )
It's pearling like crazy as there are no fish in and I just filled it yesterday.
The substrate is low-fertilized topsoil for cacti, about 1 inch and about an inch
fine white sand.



The plants in the pots (back left) are waiting to be planted (or not?) because I'm not entirely sure
how many plants I need for the tank to be (almost)self sustaining.

I'm curious to hear your ideas about it!

J
 
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#5 ·
Looks good. You can never have enough plants!

A small area in front to better see the fish is fine. I set up my 50 gal [in 2008] with a center area in front rimmed with rocks. See photo of tank at 1 week. Worked very well. I didn't put any soil in this front area, just sand.

One thing you can do is to lower the water level temporarily. This will make it easier to do water changes and increase the amount of light getting to your young plants. At this time, you don't need 65 gal of water. :)
 

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#6 ·
......One thing you can do is to lower the water level temporarily. This will make it easier to do water changes and increase the amount of light getting to your young plants. At this time, you don't need 65 gal of water. :)
I am pretty sure that you get less light at the substrate level if you lower the water level. This is because much of the light is from reflection from the glass to air interface. Reducing the water level reduces the reflection, allowing more of the light to escape through the glass. I was amazed when I did some testing with my current light system, and found that the intensity was much greater outside of the center of the tank, not less as I was expecting. Theoretically this is always the case with the glass clean both inside and out.
 
#7 ·
thank you Diana, for your kind reply! I understand that lowering the water increases ir/uv light access to the plants, but I must admit I really enjoy the bubbles travelling up and having no visible watertable for the moment. I'll see how the plants do in the coming days and if growth is too slow, I'll lower the level as you suggest. (I completely believe you that it will make water changes easier : )

@hoppycalif, thanks for your reply as well!. My reasoning about your measurement is as follows: both uv and ir radiation get absorbed by glass. Even though the visible part of the spectrum may increase because of reflection, the useful part of the spectrum for plants decreases (rapidly) with higher watertable. Even if by total internal reflection both ir and uv radiation make it to the bottom, this will be only under a shallow angle, and will definitely be offset by the (dramatic) loss of radiation through water absorption. see http://www.koppglass.com/blog/optical-properties-of-glass-how-light-and-glass-interact/ and https://en.wikipedia.org/wiki/Electromagnetic_absorption_by_water Did you measure the total lux or the intensity of ir and uv separately? I'm interesting to hear what the distribution is of those wavelengths.
 
#8 ·
Plants use light in the range of 400-700 nanometers, from near ultraviolet to near infrared. Very little radiation outside of that range is usable by plants. Light reflection from the glass sides of an aquarium occurs for that whole range also. The reflection occurs at the outside face of the glass, making it vital to keep both sides of the glass as clean as possible if you want maximum light intensity. I used a PAR meter, which covers almost all of the 400-700 nanometer range, and a little bit more. I noted as I moved the sensor from the glass towards the center of the tank, the intensity dropped significantly, instead of increasing as I was used to seeing with typical fluorescent lights. (I use a LED light panel, which spreads the light over about a 120 degree cone, so a lot of light hits the glass.)

Water does not significantly absorb light until the depth of the water is around a meter, the absorption of light isn't at all significant at 25 cm, for example. The drop in intensity with distance in an aquarium is just the result of the cone of light causing the area, the energy is in, to get larger proportional to the square of the distance the light travels, no matter what medium it travels through.
 
#11 · (Edited)
air and flow pump

Hi there, I thought I'd share this little gizmo I made to get some air into the tank, maybe it can be of use to anyone:


In order to get the plants a bit more oxygen, I put in a small waterpump (superfish aquapower 380), but I figured i wanted an airpump as well. To avoid having yet another electrical device hooked up and spending yet another €15, I made a little attachment to the pump, that sucks in air from above the watertable through the transparent tube by means of the waterflow through the green tube. Works like a charm and gives both flow and oxygen :) I'll make a nicer version of it using a 3D printer later on.
 
#13 ·
yeah, I figured that out today too :) guess I got a bit too excited about the idea for the cheap and simple solution for aeration. Whilst getting my foot out of my mouth, I'm thinking I can hook up a DIY CO2 generator (yeast/water/sugar) to the air input instead while the fish are building up confidence to come in my tank.
 
#14 ·
This type of device doesn't work with most DIY CO2 systems. It causes some suction in the CO2 line, and that can lead to sucking some of the yeast/sugar water into the tank. A much better way to do this is to stick the CO2 line into the water pump input screen. That doesn't cause any suction, and just lets the natural pressure of the CO2 cause the CO2 to bubble into the pump, where the rotor will chop it up into much smaller bubbles - possibly with some noise.

This is how I get my DIY CO2 into the tank water.
 
#15 ·
That doesn't cause any suction, and just lets the natural pressure of the CO2 cause the CO2 to bubble into the pump, where the rotor will chop it up into much smaller bubbles - possibly with some noise.
ha, that makes sense, and sounds much better. I'll have a go at it once I have my green algae under control :s (probably too much light, I'll try a light-less regime first, UV lighting second)
I'll report back :)

 
#16 ·
well, I got rid of the green algae by cutting the light entirely for two days and then to ~3 hrs a day. However, after I got rid of the algae, plantgrowth was almost 0 for the last two weeks. I investigated and the plants had developed only very small roots. I think the sand was too fine and thick (2" in places), and the substrate too shallow (< 1"). In the time since I started this thread (about a month) the substrate seems to have gone almost fully anaerobic, judging by the smell after I tore the tank down. So I've started again, and will continue reporting on my adventures in a new thread: https://www.aquaticplantcentral.com/forumapc/el-natural/143101-re-started-65g-tank-second-try.html

thanks for all the advice so far, I'll use all of it in my new setup!
 
#18 ·
well, I got rid of the green algae by cutting the light entirely for two days and then to ~3 hrs a day. However, after I got rid of the algae, plantgrowth was almost 0 for the last two weeks. I investigated and the plants had developed only very small roots.
Please don't use the light blackout regimen. Plants that don't have light can't photosynthesize and keep their roots safely oxygenated. Plants will suffer or die when the substrate goes severely anaerobic.

A UV filter will kill green water algae in a couple days with no side effects. It's one of the few gadgets that I believe is totally worth the price!
 
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