Stunted / brittle growth in new tank set-up

[guy]

Hello,

I'm new here and i am from the Netherlands. I (re) started my hobby with a 40x40x40cm tank for 2 weeks ago. my tank set up: aquasoil dennerle 15l, some rocks and spiderwood, chihiros led (a401) 8000k for 7 hours a day, in tank filter, pressurized co2 at 1 bubble/sec (my drop checker is green but not lime green). i've some rotalla's , dwarf grass, heteranthera zosterifolia and monte carlo planted in the tank, imo not the most difficult plants. I run de light for 7 hours and at 40-50%. I use on daily base, an all-in (with po4 and no3) fertilizer 2ml/day. My plants (stemplants) are brittle, the new growth is small and stunted, old leafs seem to be ok. New leafs have some decollaration (yellowish on the outside off the leafs). Not any signs of algea.

what have i done yet:
- i reduced the light one step from 60 to 40-50% and increased de co2 a little bit (a use an in-tank diffusor).
- I dose an all-inn fertilizer(with macro's) because my po4 was 0.0.
- first week tap water change 50% daily, second week every other day 33%, next week 2x/week 33%
- yesterday my parameters were: ph 6 - 6,5, Kh 2 (my tap water is 5, but i think it is due to the aqua soil), No2 0, No3 20 ppm, Po4 0,5 ppm, ammonia 0,

I'm asking myself: according to the (temporary) medium light setup, does adding co2 makes sence?
or should i increase the light instead of reducing, unless the stunted growth?

Thanks a lot!

 

[Allwissend]

Welcome!
The substrate is still new and takes up a lot of phosphate. This will go away in a few weeks, depending on how much PO4 you dose.
In the mean time, you may consider increasing your daily dose of fertilizer to keep the phosphate levels up.

The old growth is still some emersed growth so it can be that your plants are simply adjusting to being under water and will start growing larger leaves with time and PO4.

No matter how strong the light, it makes sense to add CO2. It is simply a plant nutrient and it's abundance will make it easier for plant to take it up in sufficient amounts. Then your light will be the limiting factor for growth. That's a good place to be.

 

[guy]

Welcome!
The substrate is still new and takes up a lot of phosphate. This will go away in a few weeks, depending on how much PO4 you dose.
In the mean time, you may consider increasing your daily dose of fertilizer to keep the phosphate levels up.

The old growth is still some emersed growth so it can be that your plants are simply adjusting to being under water and will start growing larger leaves with time and PO4.

No matter how strong the light, it makes sense to add CO2. It is simply a plant nutrient and it's abundance will make it easier for plant to take it up in sufficient amounts. Then your light will be the limiting factor for growth. That's a good place to be.

Thank you!

I did not knew that the new substrate consumes po4. I will increase the ferts and i pushed the co2 a little bit more. I must be carefull now because the drop checker is lime green. So i think i’m on the max for that. Light
Is still 50% at duration of 7 hours. For my opnion thats is already really bright. But the rotalla’s make new leaves but not the “feather”leaves. Does that also takes time? ( there’s not any sign of algea or dust algea)
I also have a surface film that i’ve to remove daily with kitchen paper. Does that also goes away? I dont have much surface aggitation from the “in tank” filter.

Thx

 

[Allwissend]

When it's new it does take up quite a bit but it will slow down in time. Yes, you will notice longer leaves with the Rotala as it becomes adjusted to underwater conditions, currently there are still remnants of the emersed form.

If there is no surface water movement at all, yes you will get that biofilm. With just a little rippling that should go away in a health aquarium. Alternatively, you can let ramshorn snails glide on the surface of the water and eat it. It's a nice view