180l (~47gal) tank - Page 17 - El Natural - Aquatic Plant Central

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El Natural Diana Walstad's low-maintenance, soil-based 'El Natural' method for keeping plants and fish.

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Old 11-25-2019, 09:18 AM   #161 (permalink)
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Default Re: 180l (~47gal) tank

Small change in the tank setup - I am using the air stone only during night. I believe that it increases available CO2 for plants as floaters start showing micro nutrients deficiency again - I will need to adjust the fertilization schedule. I still remove a small bucket of plants every week or two and fish slowly stabilize their numbers - there is considerably less fry swimming around. Otherwise no change, still a jungle..


Not sure why I bother taking photos, they are almost identical even if several weeks or months apart
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Old 11-26-2019, 06:30 AM   #162 (permalink)
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Default Re: 180l (~47gal) tank

Always nice to see a photo of your tank!
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Old 01-18-2020, 08:49 AM   #163 (permalink)
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Default Re: 180l (~47gal) tank

Thanks!

Yet another jungle photo and "behind the curtains" photos of my air condition system (two fans, left one forces warm air around the cabinet and cools the led light, the second one on the right draws hot humid air out of the tank - a friend of mine laser cut me a custom designed acrylic airflow "thingy"). You can see also my new addition - quite fresh Pothos plant cutting with its own light. The plastic box under the light with floating plants is temporary storage until I move them to their new home.

After I saw how big positive impact the cuttlebone had in my nano tank, I decided to add it also to this one as a preventive measure. Also I decided to push fertilization root sticks into the crypts jungle again, remaining Echinodorus which I though is dead almost immediately sprout a new leave. I guess I'll need to be more diligent with substrate fertilization. Liquid ferts and detritus somehow can't keep up with Cryptocorine demands, despite very heavy stocking and (over)feeding.



I finally found an use case for the wide angle lens on my phone (hence the distortion)






And one photo of my floating plants section of the tank. Red root floater which is directly under the light (light fixture not visible on the photo) has nice red/brown hues.
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Old 02-02-2020, 12:14 AM   #164 (permalink)
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Default Re: 180l (~47gal) tank

Small change in the setup - I didn't like big bubbles which air stone produces (they splash too much and cause stem plants to float), so I reinstalled the venturi air diffuser on the filter output - it creates a lot of tiny bubbles which don't splash much water above the surface and get around the whole tank. By the working principle it increases the water flow strength as well. I'm not sure if it's the extra flow or air (CO2?), but some plants which were almost on the verge of dying out (Gymnocoronis spilanthoides) are spreading out really successfully now. Sometimes I need to prune not once, but twice a week.

Also I see a lot of shrimp with "saddles", which I did not notice before. It is probably either due to addition of extra oxygen to the water or positive effect of cuttlefish bone (or both). In each case, I'm happy with results.

And yet another photo of my nonstandard tank
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Old 02-05-2020, 11:12 AM   #165 (permalink)
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Default Re: 180l (~47gal) tank

Does that mean if you bubble in small enough bubbles, it would actually increase the CO2 in the water? Or will it always increase degassing of CO2 (unless you're bubbling CO2, obviously)?
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Old 02-05-2020, 12:04 PM   #166 (permalink)
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Default Re: 180l (~47gal) tank

Quote:
Originally Posted by jatcar95 View Post
Does that mean if you bubble in small enough bubbles, it would actually increase the CO2 in the water? Or will it always increase degassing of CO2 (unless you're bubbling CO2, obviously)?
The air-water CO2 equilibrium is around ~0.5 ppm at 24C. If the water CO2 content is below this level, then CO2 will dissolve into the water from the air. If the CO2 level is above the equilibrium, then CO2 will de-gas from the water to the air. Generally water stirring will speed up this process. O2 dissolves faster than CO2 in water and also O2 equilibrium level is much, much higher (8-9 ppm). If there is enough O2 in the water and other needs of bacteria etc are met, then they can also produce CO2 in the tank.

The Ecology of the Planted Aquarium book contains a chart of typical CO2 level in a NPT during the photoperiod. When lights are turned on in the morning, the water CO2 level is typically much, much higher than the equilibrium level (the chart shows 5-10 ppm CO2 in the morning if I recall right. Please double check.) . This example indicates to me that water stirring will likely reduce the CO2 content of the water under such conditions.

Think about it. 0.5 ppm is really not that much. C is the macro nutrient that plants need in the largest amount to grow. Estimative Index with CO2 dosing goes for a constant (which is quite impossible to maintain imho) ~30 ppm which is 60x higher!

@Mysiak's tank also contains tons of fish. With such a high fish load, it is especially important that O2 level does not drop below a critical level. During the photoperiod, plants may produce O2 from CO2, but not at night.
I have quite a few NPT tanks with much fewer fish than Mysiak's tank and I have never ever seen fish gasping for air even if I did not have any air stones or any water stirring (i.e filter).
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Last edited by zolteeC; 02-05-2020 at 10:38 PM.. Reason: typo corrected
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Old 02-05-2020, 03:08 PM   #167 (permalink)
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Default Re: 180l (~47gal) tank

Water movement in the tank help distribute CO2 and nutrients around for plants. Plants have a harder time absorbing CO2 in water than in air because gas diffusion is slow in water (slow kinetic energy)... So, water movement help the diffusion rate. Usually a higher CO2 concentration helps.
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Old 02-05-2020, 11:31 PM   #168 (permalink)
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Default Re: 180l (~47gal) tank

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Originally Posted by mistergreen View Post
Water movement in the tank help distribute CO2 and nutrients around for plants. Plants have a harder time absorbing CO2 in water than in air because gas diffusion is slow in water (slow kinetic energy)... So, water movement help the diffusion rate. Usually a higher CO2 concentration helps.
This is all true, but really the question is to me how water stirring and air stone impacts the conditions in the tank for plants and inhabitants. I guess it's rather obvious, if O2 levels are too low for the fish, then stirring or air stone or some other means of increasing O2 level in water is absolutely needed.
I don't quite know the physics of air bubbles and air stones, my guess is air bubbles introduce some water stirring and also increase the water-air surface (due to the surface of the air bubbles). The gas pressure of the air bubbles is approx 1 atm (tanks are not too deep) and bubbles contain the same gases as air (O2, N2, CO2, ...).
Let's say we have a healthy NPT where CO2 level is -say- 8 ppm at the end of the dark period. This is 16x higher than equilibrium level! O2 levels are reasonable for fish during all times. When light turns on, plants will consume this CO2 in couple of hours. My thinking is, that if we're increasing stirring significantly in this tank then it is possible that we will not reach the healthy 8 ppm CO2 level in the morning but much lower level thus plant growth may be limited.
I have quite some NPTs with no water stirring nor air stones. Plants are growing well and fish are happy. However, I think Mysiak's tank in this topic differs quite a bit from my tanks due to the heavy fish load.

Last edited by zolteeC; 02-06-2020 at 12:26 AM.. Reason: typo
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Old 02-05-2020, 11:45 PM   #169 (permalink)
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Default Re: 180l (~47gal) tank

My thinking and observations in this tank are:

a) no extra aeriation - plants and fish produce so much CO2 during night, that fish are gasping for air during night and a few hours in the morning. Extra CO2 is consumed by plants quickly during main photosynthesis period. After that, CO2 is provided mostly by fish/bacteria, which by observation isn't enough.

b) aeriation only during night - fish show no discomfort during night or day, but plants do not have any extra CO2 boost in the morning.

c) 24/7 aeriation - fish are completely fine. Plants have stable, albeit small, concentration of CO2 at any time and with better distribution due to increased flow.

I want to avoid obvious fish discomfort, so a) is out of the question. With proper equipment, I could schedule night aeriation adequately to provide extra CO2 for plants, yet safe environment for fish. But as I do not have the abilities, b) is out as well. Option c) is IMHO a safe bet where nothing can go wrong - plenty of O2, "just enough" of CO2 24/7.

But again, I am speaking strictly about this "well stocked" tank with many fish and plants.

Btw. standard air stone works mainly by disrupting the water surface and a bit of extra water movement. Venturi air diffuser produces much smaller bubbles which stay in the water column much longer, which at least in theory, helps with gas exchange.
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Old 02-06-2020, 12:41 AM   #170 (permalink)
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Default Re: 180l (~47gal) tank

I am wondering why case b) is not an option in this tank. Since your tank is "well stocked", when lights are turned off, probably fish start to consume "too much" O2 and O2 levels get depleted without air stone (or other means of increacing O2 level). Probably at the end of the light period your O2 may even be above the equilibrium (which is approx ~8 ppm) because of plants. I saw a study which stated that Zebra Danio fish was happy with O2 level above say ~3 ppm. So you could start an air stone or a bit of water stirring after the lights go off. When exactly? I don't know. How much? I don't know.
There must be "enough" water stirring or air bubbles to be always on the safe side when it comes to possibly low O2 level. However, every time your CO2 level is above the equilibrium, water stirring or air stones will speed up de-gassing and the degassed CO2 will be lost for the plants to potentially use. (I guess your tank has more CO2 than the equilibrium most of the time. After all it has soil, lots of fish and good fish food input. I guess only when plants use up CO2 due to heavy photosynthesis you have less than .5 ppm CO2.)
I've read somewhere that O2 dissolves in water faster than CO2 from air which may be a good news for fish.

Anyway, I kind of agree with "Don't touch if it works", and your tank definitely looks like it works fine!
All I wrote above is top of my head and may be wrong or its also possible that I do not remember the numbers correctly. So please double check everything before you take it too seriously .
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Last edited by zolteeC; 02-06-2020 at 12:59 AM..
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