Question on keeping/changing substrate for plant growth

[Paristheprince]

Hello guys,

I have had a 30 gallon tank for about 6 months now which completed cycling about 3 months ago. I have a couple of plants in the tank that are growing at super slow pace. I really want a tank with vibrant plants to create a natural background for the tropical fish. I currently have this type of substrate covering the bottom for about 2 inches:

I know that for better plant growth I will need a soil-based substrate. I am a little hesitant to totally replace the substrate with soil-based substrate out of the fear that it will suddenly rid the aquarium of the beneficial bacteria living in the blue gravel and cause an ammonium spike. Plus, it will uproot the plants that already rooted in the blue gravel. I was wondering if anyone has any advice as to whether it is totally necessary to replace the substrate to induce plant growth. Is there any way around that? Unfortunately, my tank is in a low-light place as well and I cannot move, so I am wondering how best to plant and grow plants efficiently in these conditions. I would appreciate advice from y'all. Thank you!

 

[Colin_T]

Most aquarium plants will take nutrients through their leaves and don't need a plant substrate.

I used Sera Florena liquid plant fertiliser, but there are other brands of iron based aquarium plant fertilisers too. Have the iron (Fe) level at 1ppm (1mg/l) and give the plants some light and they should grow.

It also depends on what plants you have and some plants sold at shops do not belong in aquariums and will struggle to grow.

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LIST OF PLANTS TO TRY
Some good plants to try include Ambulia, Hygrophila polysperma, H. ruba/ rubra, Elodia (during summer, but don't buy it in winter because it falls apart), Hydrilla, common Amazon sword plant, narrow or twisted/ spiral Vallis, Water Sprite (Ceratopteris thalictroides/ cornuta).
The Water Sprite normally floats on the surface but can also be planted in the substrate. The other plants should be planted in the gravel.

Ambulia, H. polysperma, Elodia/ Hydrilla and Vallis are tall plants that do well along the back. Rotala macranda is a medium/ tallish red plant that usually does well.

H. ruba/ rubra is a medium height plant that looks good on the sides of the tank.

Cryptocorynes are small/ medium plants that are taller than pygmy chain swords but shorter than H. rubra. They also come in a range of colours, mostly different shades of green, brown or purplish red. Crypts are not the easiest plant to grow but can do well if they are healthy to begin with and are not disturbed after planting in the tank.

Most Amazon sword plants can get pretty big and are usually kept in the middle of the tank as a show piece. There is an Ozelot sword plant that has brown spots on green leaves, and a red ruffle sword plant (name may vary depending on where you live) with deep red leaves.

There is a pygmy chain sword plant that is small and does well in the front of the tank.

 

[itiwhetu]

I only ever use natural river gravel, and I find that everything that you need for plant growth slowly leeches out of that gravel.