[rafael.nicolaidis]

Hi folks

Been keeping a small "low tech" tank (60 x 20 x 20 cm) for 5 months.

Plants are mostly Eleocharis mini, Mayaca fluviatilis and some Salvinia.
I´ve been dosing the tank with Seachem Flourish daily, around 6 drops per day.

Substrate is MBreda Amazônia, a local aquasoil brand (3 mm granules; TiO 0.05%; K 0.24%; Ca 1.05%; Mg 0.84%; Fe 0.27%; Al 1.16%; Si 6.35%; N 0.40%; P 0.07%; S 0.34%; Na 0.0009%; Mn 166.9 ppm; Zn 292.5 ppm; Cu 14.2 ppm; B 63.8 ppm; Electrical Conductivity 1,600; CTC 15.5 me/100g). There are some basalt stones here and there.

Water is absolutely still.
Water parameters are: ammonia 0, nitrite 0, nitrate 5 mg/l; pH 6.8, KH 1; GH 8; Fe 0.05 mg/l.
I do a partial water change weekly with tap water (pH 6.4, KH1, GH 2, remineralized with Seachem Equilibrium). I do top offs as needed, with distilled water.

I´ve been keeping the tank at room temperature, which at this time of the year oscilates between 16 and 24 °C most of the time.
The tank sits by a window and receives only natural sunlight. In that place, light is more intense in the first 2-3 h of the after sunrise.

At the moment it houses only 1 Poecilia vivipara fry and some snails and smaller invertebrates.

I am having problems with the Eleocharis. It has been more than a month that I have noticed it has been losing leaves. In the beginning I thought it was a normal thing (never had a tank so full of hairgrass, did not know what to expect). But in the last weeks it has become evident that the carpet is thinning in the right corner of the tank. Two times this month I inserted root tabs in that area, but noticed no improvement.

Bellow is a picture of the tank before the issue manifested. Tomorrow I´ll try to take a picture of the thinning area.

Can you guys help me?

 

[mistergreen]

Eleocharis grows well with CO2. Maybe the mass of plants is competing for CO2 and some are losing out.

 

[MudLily]

There are 2 possibilities I would be considering.

1) The plants reached a point of density where light competition became a growth-limiting resource. You're now seeing the population rebound off their upper density threshold and will notice the tank gradually thin out until it stabilizes.

2) The nutrient reserves in your soil are starting to get used up. Your plants are now running into macro deficiencies causing old growth to be reabsorbed in order to continue putting out new growth in hopes of reaching a better environment for sustained growth again.

Seachem Flourish and Seachem root tabs provide a pretty low concentration of everything compared to other comprehensive brands on the market, and actually end up providing less while costing more over time.I've since moved away from the line for this reason (I do still use root tabs, but more as an alternative supplementary source).

You could load up a calculator and figure out the target dose brands like NilocG Thrive are formulated to provide, and then find the equivalent dose of flourish to hit those targets. I would aim to match Nitrogen concentrations as a guiding reference.

EDIT:
Did the leg work...

1 recommended dose of Thrive is equivalent to using approximately:
3x dose of Flourish comprehensive
5x dose of Flourish Nitrogen
8x dose of Flourish Phosphate
2x dose of Flourish Potassium

So you see why I stopped recommending Seachem, but for some people that's all they can get.

 

[rafael.nicolaidis]

Eleocharis grows well with CO2. Maybe the mass of plants is competing for CO2 and some are losing out.

Thanks, @mistergreen , I think CO2 may be part of my problem. However, the issue is happening in a specific section of the carpet and nowhere else.
Since your observation, I have started to do my partial water changes with distilled water (remineralized for GH), hoping to improve "natural" CO2 solubility.
Still unwilling to go the pressurized CO2 route, specially in this small tank. Maybe in another one in the future.

1) The plants reached a point of density where light competition became a growth-limiting resource. You're now seeing the population rebound off their upper density threshold and will notice the tank gradually thin out until it stabilizes.

Thanks, @MudLily , I will keep that in mind, I have a luminary of adequate size for that tank. Never installed it because I thought being so close to the window the light would not be a limiting factor. Interestingly, that corner of the aquarium receives the most direct natural light. Removed most of the Salvinia anyway, so that it doesn´t make lots of shadow.

2) The nutrient reserves in your soil are starting to get used up. Your plants are now running into macro deficiencies causing old growth to be reabsorbed in order to continue putting out new growth in hopes of reaching a better environment for sustained growth again.

Now this I think may be the most important factor. I have noticed an improvement in the last week and I think it may be due to the root tabs.

Seachem root tabs provide a pretty low concentration of everything compared to other comprehensive brands on the market, and actually end up providing less while costing more over time.I've since moved away from the line for this reason (I do still use root tabs, but more as an alternative supplementary source).

I am not using Seachem tabs. I am using a gardening brand. It doesn´t disclose which form of N is in it, but I believe it may be urea. It is 20% N, 10% PO4, 5% K, 8.6% Ca and 4.78% S. Doesn´t add micros, but lots of NPK.

TY!

 

[mistergreen]

Yes, the section that receives the most light will require the most nutrients and co2.