Food web

[bijouxcailloux]

Hello all!

So we have a 240L tank, biotope Guyana, with 4 maroniis, 3 nannacara, 15 gold tetras, 7 marbles hatchefish, and 8 corydoras nanus.

The pH is around 7, but we are trying to make down to 6/6,5 with oaks extract.
For the decoration, one big roots and a lot of leaves from Amazonia, some dry fruits, oaks leaves..

So the idea was to create a biotope and I would like to stop the moment of food when there is so much stress for everyone. We're trying to feed less but more often, giving there and there some mosquito larvae, ants, more spontaneous like in nature.
So my question is can we create some food chains, like with daphnia or some crustaceans ?
We're thinking of the worms, but I have too much fear of the parasite. (Which can live his life cycle endless)

Maybe you have some tips how to feed as close as a natural environment?
Have a good day,
Camille

 

[MacZ]

The pH is around 7, but we are trying to make down to 6/6,5 with oaks extract.

Instead of chasing a pH, focus on hardness/conductivity. If your pH is 7 it's fair to assume you have a measurable KH and if that's the case you will not do much with the extract except if it's just acid sold as such. (Which is sadly often the case.) Then you will raise conductivity while lowering pH and that's the opposite of what you want.

So the idea was to create a biotope and I would like to stop the moment of food when there is so much stress for everyone. We're trying to feed less but more often, giving there and there some mosquito larvae, ants, more spontaneous like in nature.

Feeding is not a stressful situation. If you want to get close to natural feeding stick to white mosquito larvae, cyclops and daphnia as staples, flightless drosophila from the terrarium supply for the hatchets, worms for the bottomfeeders and rotate other live foods.

So my question is can we create some food chains, like with daphnia or some crustaceans ?

Bluntly and frankly: No. Closed food chain systems are impossible by design. Nutrients have to come from somewhere, and even with regular addition of leaf litter, botanicals and wood, it will not be enough to keep a population of invertebrates really going. In nature you will be surprised how much detritus these fish eat and how much of really small fauna is filtered from the sand and leaf litter by chewing.

We're thinking of the worms, but I have too much fear of the parasite. (Which can live his life cycle endless)

The only bigger invertebrates that may possibly have a chance are worms like blackworms or tubifex. Tubifex may carry Myxobolus if wild caught but depending on where in the world you live chances are slim.
Otherwise go smaller and try infusoria that can make mulm and detritus from leaf litter a food source itself. Also Aufwuchs of all kinds like biofilms is a welcome source of food.

 

[bijouxcailloux]

Thank you so much for this detailed explanation!
For the pH, the acid and the conductivity:
We have at the moment pH 7,5 KH: 7. Later I can provide the GH information.
How could we lower the kh so the pH can also decrease and a low conductivity?
(It seems like you understand this topic! )

 

[MacZ]

Simple:
Use RO or rainwater as source water. KH as a buffer system determines pH. The higher the KH, the higher the pH. The trick is using water without KH in the first place. Humic substances (aka "tannins") buffer in a range betwen 4 and 6, which is exactly what you need.

 

[MacZ]

Later I can provide the GH information.

If your KH is at 7°, GH is likely around 10.

 

[bijouxcailloux]

I see I see!
And the relationship with tannin?
Because we have it hard to keep it. We put some palm tree stuff who has a high portion of tannin.
It's in the water for like 2/3 days ..
Is it linke with this question of pH and kh?

 

[MacZ]

Tannins are a group of substances within the larger group of humic substances. Botanical material releases substances of said group while decomposing in water until it is completely broken down to detritus. Most of these substances are weak organic acids and as such they bring H+ Ions (pH measures the concentration of H+) into the water, hence lowering pH. Just in contrast to strong non-organic acids (like sulfuric acid or hydrochloric acid, which are often used in "oak extract", which btw often has never seen an oak tree.) these weak acids do neither raise conductivity nor do they drop pH uncontrollably.
Even with strong ion exchanging materials like peat it's almost impossible to drop pH as fast and as far that it becomes a problem. At the same time the usual balance between pH, KH and CO2 is moved by dropping pH via another source of H+ Ions.
Both KH and CO2 strife to balance out if untouched, resulting in a specific pH.
Meaning, neither is more CO2 solved in the water, nor are carbonates generated in higher concentration, which would counterbalance CO2 as well.

So in short: Humic substances replace the KH/CO2 buffer system. They can not be changed and shifted as easy as CO2 (by injection) or KH (by mineralizing with mineral salts), they can't even be measured without a lab, but luckily they also do not harm anything if added in higher concentrations.

Now for sources of humic substances, botanicals are a good source, as they release small amounts while breaking down, but do so constantly. It takes time and accumulation of organic botanical material to take greater effect, but it's worth it in my opinion. Humic substances from botanicals can counter only very low KH of maybe 1°, even with 2° of KH, it takes months to see any significant changes.
Peat on the other hand releases a lot more a lot faster, which can even counter smaller KH-Levels (up to 5°) and softens water to a certain degree in KH, while not in GH.
So as any acid will have to counter KH, and the weak acids are only able to do so to a degree, soft water without KH and GH is a prerequisite to get into lower pH-ranges.

The only thing one has to keep in mind is: Freshly added botanical material is being colonized by microbes quickly and depending on the amount of material, this colonization may use up a lot of oxygen, causing a short term oxygen depletion, which can be easily countered by an air-stone.

And another word of advise: As humic substances derive from natural products like leaves and peat, you will have to experiment a bit with each new batch, because levels may vary a lot.

Oh, and before I forget: The water most dwarf cichlids live in in the wild is even softer and more acidic than the water we can produce in the aquarium. It takes a bit more effort to closer recreate it.