Why can't you have the light on for more than 9 hours?
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Most aquarium plants like a bit of light and if you only have the light on for a couple of hours a day, they struggle. If the light doesn't have a high enough wattage they also struggle. Try having the tank lights on for 10-12 hours a day.
If you get lots of green algae then reduce the light by an hour a day and monitor the algae over the next 2 weeks.
If you don't get any green algae on the glass then increase the lighting period by an hour and monitor it.
If you get a small amount of algae then the lighting time is about right.
Some plants will close their leaves up when they have had sufficient light. Ambulia, Hygrophilas and a few others close their top set of leaves first, then the next set and so on down the stem. When you see this happening, wait an hour after the leaves have closed up against the stem and then turn lights off.
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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 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.
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If you add an iron based aquarium plant fertiliser, it will help most aquarium plants do well. The liquid iron based fertilisers tend to be better than the tablet forms, although you can push the tablets under the roots of plants and that works well.
I used Sera Florena liquid plant fertiliser but there are other brands too.
Do not bother adding carbon fertiliser to the tank because they are not necessary.
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We use to grow plants in 1 or 2 litre plastic icecream containers. You put an inch of gravel in the bottom of the container, then spread a thin layer of granulated garden fertiliser over the gravel. Put a 1/4inch (6mm) thick layer of red/ orange clay over the fertiliser. Dry the clay first and crush it into a powder. Then cover that with more gravel.
You put the plants in the gravel and as they grow, their roots hit the clay and fertiliser and they take off and go nuts. The clay stops the fertiliser leaching into the water.
You can smear silicon on the outside of the buckets and stick gravel or sand to them so it is less conspicuous. Or you can let algae grow on them and the containers turn green.
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We did plants in pots for a couple of reasons.
1) I was working in an aquaculture facility and we grew and sold live plants to shops. Some of the shops wanted advanced plants in pots so we did that.
2) Plants like sword plants love nutrients and have big root systems so they needed more gravel and big pots. When given ideal conditions these plants would produce lots of runners with new plants on and we got more plants to sell.
3) Most of the tanks only had a thin layer of substrate that was nowhere near thick enough for plants to grow in so having them in pots allowed us to grow plants in tanks with minimal gravel in the tank.