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Maq's Substrate Experiment

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At last, the experiment has begun. Let me summarize basic data & thoughts here so that you don't have to read through the whole thread.

The aim of the test is to compare the early development (three months, perhaps) of tanks with silica sand and aquasoil. Also, one tank contains root fertilizer; I'm curious whether it would make any difference.
You can see my workshop here. There are four identical tanks with net contents 20 liters. I call them "Micurins" and individual tanks are named (from left to right) A, B, C, D. This is Maq at work so it's needles to say that no CO2 enhancement is employed, as well as no filtration. Internal pumps AquaEl 500 circulator without venturi make the water move quite vigorously, all plants are visibly moving in the current. Temperature was 16 °C, but the pumps are likely to warm the water by 1 or 2 degrees. Lighting is an old Chihiros 1200, all LEDs are white. Running at approx. 30-40 % of maximum performance. Photoperiod is 7 hours a day with 2 hour siesta around noon. Some very young snails (ramshorns) were deliberately introduced with plants.
A - silica sand is in fact a control. Three liters of carefully washed sand size 1.4 to 2.0 millimeters.
B - root tabs. The same sand but 32 beads of Osmocote fertilizer spread at the very bottom. I've dried the sand in the oven not to initiate ferts dissolution with adding the sand but only after filling the tank with water.
C - aqua soil. I've used 3 liters of ADA Amazonia ver. 2, without the Amazonia supplement.
D - custom. This is the same silica sand but enriched with an additive. @Simon Cole had the idea which I'm about to check whether it's of any value. For now, I will not disclose details, yet I can tell you that it's not any kind of "nutrient depot" or so.

I've established tanks C & D on Nov 13th. I've poured RODI water in them just enough to make the substrate moist but not fully submerged. I rather think that such a "bog" arrangement is better for cycling than anything else. But I can be mistaken, of course.

The Day Zero was on Dec 7 th. I've added the sand in tanks A & B and then filled the tanks with RODI water. After that, I've checked the conductivity with following results: A - 7 µS/cm, B - 5 µS/cm, C - 26 µS/cm, D - 10 µS/cm. Then I planted the plants:
Grasses
Tonina fluviatilis - one cutting with apex from my stock.
Monocots
Blyxa japonica - one rosette (the plants arrived rather weaker than what I'd imagined).
Cryptocoryne albida Brown - a group of quite small plants. I've been keeping this species for quite long already, and it remains small in all tanks. So, I'm curious whether aquasoil or root tabs would make a difference.
Dicots
Ammannia gracilis - tissue culture.
Ludwigia inclinata Meta - two cuttings with apex from my stock.
Ludwigia repens - one short cutting with apex. I didn't plan this species but my dealer added it as a gift, so why not?
Lysimachia nummularia - I've got damned seven cuttings so they are by two in all tanks except A. This species is not particularly demanding but its transition from emersed to submerged is often problematic.
Myriophyllum tuberculatum - two cuttings, one with and one without apex.
Rotala macrandra - tissue culture.
Rotala wallichii - one cutting with apex from my stock.

Here you can see a schematic map:
1702122869504.png
Next day (Dec 8 th) I mineralized/fertilized the water like this:

1702123997572.png

You can see that the dosing is lean. I think it's the best way to see if root tabs or aquasoil contribute to improved growth.
I'm planning to change 50 % water weekly, with front loading re-calculated to 10 liters.
A few hours later I've checked the conductivity again: A - 35 µS/cm, B - 35 µS/cm, C - 106 µS/cm, D - 46 µS/cm. It seems that aquasoil is leaching some substances.

A(02).jpg


B(02).jpgC(02).jpgD(02).jpg
 
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_Maq_ said:
1702123997572.png
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Maq, anyway for you to put them in ppm instead of Molars? Most of us are use to looking at ppm. You can probably put both Molars and ppm on the same picture for us. Thank you

Edit: nevermind, I somehow missed the mg/l on the right side.
 
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What is your test equipment and method for each data point? Apologies if you've described this before as I skimmed this thread and your previous '23b' thread and did not see anything. Mostly curious how you're measuring to two decimals on the nitrogen components. 🙂
 
_Maq_ said:
data

View attachment 213684
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I really like these Silica Sand water parameters. Not attainable unless you use a high quality RO-DI system and of course dose homeopathic amounts of fertilizers and minerals. I don't particularly like the look of the sand though.

Will be interesting to see how the aqua soil performs vs the plain silica sand. It was never super obvious to me why enriched substrate (as evident from the high EC) is such a big deal for some hobbyist. I don't really see much evidence around that suggest you can't accomplish the same with just water column dosing or perhaps initially prime the pump with a bit of root tabs... anyway, I guess this is what this experiment will help shed some light on 🙂

If asked, my recommendation would be to go inert with reasonably grain size (1.5-2.5 mm) to promote flow and a substrate color you like. In my own tanks I use inert gravel but the grain size is 4-5 mm and I am not happy with the looks... Lesson learned 😉

Cheers,
Michael
 
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MichaelJ said:
I don't particularly like the look of the sand though.
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Neither do I, but I don't trust artificially coloured sands. Such a substrate is effectively formed by some kind of plastic. The big unknown is its adsorption qualities.
MichaelJ said:
Will be interesting to see how the aqua soil performs vs the plain silica sand. It was never super obvious to me why enriched substrate (as evident from the high EC) is such a big deal for some hobbyist.
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Yes, I'm curious, too. But the question is not limited to the amount of nutrients only. The grains of aquasoil are microporous and contain clay. I quite believe clay is beneficial, not only as a source of CEC, but that plants' roots somewhat "like" it.
Actually, my substrate of choice would be (in Dec 2023 - my knowledge & experience still developing) silica sand with minor addition of powdered clay. (And ferric oxide dust at the very bottom.)
 
A fact that seemingly evaded attention is that I've detected ammoniacal nitrogen in all tanks higher than total nitrogen I delivered with fertilizers (16 µM). What does it mean? I can see two sources: (1) remnants of agar in tissue culture plants, (2) the plants themselves, leaching from injuries sustained during manipulation. These fluids apparently contain amino acids and other compounds of reduced nitrogen.
Such an observation calls into question the common practice of 'feeding' bacteria with fish food etc. I've repeatedly cycled tanks successfully without anything but silica sand and plants. It seems that plant themselves are enough to start and feed fairly complex microbial colony.

Another point of interest is the high level - in fact, very high level - of ammoniacal nitrogen in tank C - aquasoil. It seems that 25 days of 'dry cycling' did not work very well and nitrification remains far from established. Secondly, once the microbes begin oxidizing (=nitrifying) that ammonium, I expect the pH fall down quite substantially.
 
_Maq_ said:
Such an observation calls into question the common practice of 'feeding' bacteria with fish food etc. I've repeatedly cycled tanks successfully without anything but silica sand and plants. It seems that plant themselves are enough to start and feed fairly complex microbial colony.
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Around here I think that is de rigueur ... When breaking in a new tank all you need to do is plant dense preferably with fast growing plants and feed your plants from the get go, wait for some new growth and a bit of mulm and detritus from organic waste to build up and your tank is pretty much broken in and ready for livestock to be introduced ... No need to add any additives or magic potions or perform any rigorous testing... arguably you can probably speed up the process of getting a microbial community started with some gravel or filter media from an established tank but no need to buy any questionable additives or potions.

Cheers,
Michael
 
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hax47 said:
How do you explain the comparable amounts of NH3 and NH4 at such a low pH?
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That's misunderstanding. It's only one measurement expressed in three different ways. It cannot measure separately dissociated and undissociated ammonia/um.
 
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