Lowtech tank unknown issue with easy plant

[John q]

I'm really curious of your findings, personally I think there is absolutely no need to add any additional carbon in any form

My findings are not scientific but over the last 3 years I've seen lower leaf drop and those unmistakable pinholes in various sp of Hygrophila, the root cause was generally poor circulation.

Lol, I'm not for one second suggesting adding any unnatural amounts of carbon, mother nature can supply enough of that.
What is needed is some surface agitation, decent gaseous exchange and a bit of circulation around the tank. If @Heelllooo follows your advice in post #5 regards the floating plants and redirects the filter outflow so there's better circulation, I'm sure we'll see improvements in the tank.

 

[_Maq_]

while plants generally living in shadowed areas grow at much slower rate because they can utilize CO2 at much lower rates - and this is mainly because of lower energy coming from the light.

Shadowed area isn't the same as an area covered by floating plants. Floating plants are in remarkable advantage not only thanks to better illumination, but also better access to carbon dioxide and oxygen (from atmosphere). At the same time, they prevent gas penetration below because they occupy much of the surface area and don't enrich the water column with oxygen nor carbon dioxide.
As a result, areas under floating plants canopy are seriously depleted of carbon dioxide and - perhaps even more importantly - oxygen. Adding to that, emerged and floating plants are in strong advantage in competition for nutrients (they are getting much more energy from much stronger photosynthesis).
In nature, areas like this are devoid of submerged plants, and often even animals can't live there due to lack of oxygen.
Lack of oxygen has some further detrimental effects. Microbes are forced to respire other electron acceptors (nitrates, iron, sulfates), and, as a result, various harmful substances develop. Plants can defend against them, but it again requires energy. Floating and emerged plants in your tank have a plenty of energy, but submerged plants don't. They suffer and slowly die off.

the root cause was generally poor circulation

I think what we call "need for good circulation" is in fact a need for good gas (CO2 & O2) supply.
But yes, the water needs to MOVE, and at least half of the floating plants should get removed. I'm less sure about the influence of emerged plants (Scindapsus/Epipremnum) rooting in the tank.

 

[MichaelJ]

I think what we call "need for good circulation" is in fact a need for good gas (CO2 & O2) supply.

Definitely. Nutrient distribution is the key. In my own tanks I am much more worried about stale areas that are underserved with nutrients (CO2/O2/fertilizers) rather than areas that may not get enough light. Of course, there is a limit to how low you can go with light, but at least easier plants seems fairly flexible.

This is an older photo of a darker area in one of my low-tech tanks. Its quite truthful to the actual amount of light hitting those crypts, and they are doing just fine. A little extreme perhaps, but I also run my lights for 12 hours per day.

Cheers,
Michael

 

[Heelllooo]

Ok thanks for all the advices,

Right now I'm going in vacation so except for the floating plants which I will remove heavily before, nothing going to change to much.
But when I come back I will install a new filter ( dyi canister that I made in another thread ) with lily pipes which will hopefully help me increase the circulation in the tank and more importantly make it more even.

But I'm afraid I'm already at the max of what's optimal for my Betta, she seems stressed whenever I put the outflow of my filter less against the wall.

In the end if I have to sacrifice some plants for the well-being of my fish, I will.

Next time I will do a high teck tank with crazy high flow and fishes that loves it and I will have a totally different range of issue. 😂

 

[MichaelJ]

Next time I will do a high teck tank with crazy high flow and fishes that loves it and I will have a totally different range of issue. 😂

Haha, for sure... but seriously, its not really about creating an environment where your fish are twirling about like caught in a category 5 tornado... optimal flow is really a subtle thing you can certainly make happen even with livestock that hate high levels of water movements... just a simple Aquael Pat Mini (I use two in each of my 150L tanks in addition to two Tidal 35 HOB's) directed towards the substrate level (not directly at the substrate though) which is often underserved, may create just enough flow to optimize nutrient distribution.

Cheers,
Michael

 

[John q]

Next time I will do a high teck tank with crazy high flow and fishes that loves it and I will have a totally different range of issue. 😂

Having crazy high flow and added Co2 isn't always a guarantee the dreaded leaf drop and pinhole issue will be fixed. Here's a picture from the back of my tank where the circulation is poor.

 

[Heelllooo]

Some times has passed and I have some answers.

Like I said previously, before going on vacation, the only thing I changed was throwing a lot of the floating plants and the plant continued dying during the following days.
I left my home with the last stems of hygrophilas and the althernantheras worse than on the first pictures.

I left 3 weeks and the fertilisation was continued by a family member during this period.
Of course the tank has been totally covered by floating plants in less than a week.
And when I came back the plants with issues had not melted more, neither grown. They were in pretty much the exact same state as I left them.
Only the pogostemon helferi ( which was doing well before ) had taken a big toll.

I've tried changing the flow pattern a bit but my betta doesn't like it, so only a marginal improvement.
I removed a lot of the floating plants again and the sp concerned started dying again.

Until i started injecting via DYI yeast Jello Method.
The plants are now growing as you can see on the pictures below.
Still they are showing some curling and some small holes, but at least they are not dying.

Other plants are pearling and doing really well except for the Hairgrass still not growing.

So I think i can conclude it was a CO2 defficiency certainly link to the bad flow in my tank and other underlying issue ( calcium ? Why do the hygrophila leaves are curling ? )

And now I have some staghorn in the tank but it seems to be stabilising.