Why do my plants stop growing?


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A reader asks for advice on adding stem plants to her aquarium. PFK expert Jordan Stirrat advises.

Any stem plants I add to my aquarium grow really well for a few weeks and then seem to run out of steam. Have you any idea why? The tank is 120x40x40cm and has LED lighting.
I have fertiliser tablets in the substrate. I’ve tried Hygrophila several times, red Ludwigia and different types of vallis. The Ludwigia grew well at first and went quite red but after three months it’s now looking stunted and sad like all the other stem plants I’ve tried.


Jordan says: There can be many factors that determine the health of our aquarium plants, but quite often it comes down to a few simple key components. 

Firstly, it’s important to start with a good base. A nutrient rich aquasoil will provide the broad spectrum of nutrients your plants require. Adding additional root tabs can be helpful in certain circumstances but have to be replenished after a few months, depending on the manufacture guidelines. Other substrate systems equipped for growing healthy plants could include a nutrient rich base layer substrate capped with gravel.

I would suggest using an all in one liquid fertiliser, starting with the recommended dosage and increasing if necessary, depending on plant health. Some all-in-one fertilisers will include nitrogen and phosphorus which is ideally used in planted aquariums after the initial few months. Other all-in-one fertilisers don’t include nitrogen or phosphorus and are suitable for new planted aquariums up to a few months old or aquariums with little plant mass and a high fish load. Most brands will provide both of these options and you should always check their advice first. Everyone has a different method and there are many ways to achieve similar results.

Lighting is important for plants, but it’s more important to select plants that thrive under the strength of lighting you currently have. The plants you’ve listed should be suitable for most lighting strengths. Similar principles can be applied to CO2 injection. If you don’t currently inject pressurised CO2, then it’s important to pick plants that can grow in that environment.

If you apply these principles to your planted aquarium, there is a very good chance you will succeed.