Diagnosing Problems with Aquarium Plants
Cultivating a thriving planted tank can be a very rewarding experience but many aquarium hobbyists underestimate the time and dedication it takes to do it right. Not only do you need to provide your live plants with plenty of light and space to grow, but you also need to make sure they receive adequate nutrients. Like aquarium fish, live plants cannot thrive unless all of their basic needs are met. Unfortunately, many aquarium hobbyists do not understand these basic needs and, thus, they end up experiencing problems with keeping their plants alive.
If you hope to cultivate a thriving tank it would be beneficial to familiarize yourself with these common problems so you will be able to avoid them. In the event that you do experience one of these issues in your tank, you will be well-equipped to handle it properly. In this article you will receive an overview of some of the most common problems with freshwater aquarium plants and tips for remedying them.
Plant Leaves Turning Yellow
Live aquarium plants come in a variety of colors but the most common color is green – if the plants in your tank begin to turn yellow, it could be a sign that there is a problem with the conditions in your tank. As mentioned earlier, plants are photosynthetic organisms that utilize light as an energy source to facilitate biological processes. Without adequate lighting, live aquarium plants will fail to thrive and they may even begin turning yellow. Novice aquarium hobbyists often underestimate the lighting requirements for aquarium plants and they find that, after introducing the plants to their tank, the leaves begin to turn yellow because their previous environment was well-lit.
If your plants are turning yellow, another possibility is that the plants in your tank are not receiving enough nutrients to facilitate healthy growth. If you plan to keep more than one or two live plants in your tank you should definitely consider using some kind of fertilizer under your substrate to provide nutrients for your plants. If you only have a few plants, you could try using root fertilizer plants to stimulate healthy growth. The most commonly recommended substrate to use with planted tanks is Eco-Complete. Not only does this substrate contain more than 25 minerals that live plants need to survive, but it also contains live beneficial bacteria to help turn fish waste and uneaten fish food into usable food for plants.
Problems with Growth Rate
When it comes to problems with the growth rate of aquarium plants there are two possibilities – the plants are either growing too slowly or too quickly. The most common of these problems is slow growth rate and it is often due to a lack of adequate lighting, nutrients or carbon dioxide (CO2) – these are the three things aquarium plants need in order to thrive. Examine the setup you have in your tank to determine which of these three factors might be the issue. Does your lighting system provide at least 3 to 5 watts per gallon of full-spectrum light? Do you have a layer of fertilizer in place under your aquarium substrate? What is the CO2 level in your tank? Installing extra lighting or fertilizer are both fairly easy but increasing the CO2level in your tank may involve the use of a CO2 injector.
On the other side of the spectrum is the issue regarding aquarium plants growing too quickly. If you have too many plants in your tank or if you stocked your tank with fast-growing species, it may not be long before they begin to take over. Having a large number of plants in your tank isn’t necessarily a bad thing because it will keep the oxygen levels in your tank high, but it could eventually detract from the tank’s appearance and may limit free-swimming space for your fish. To control the growth of your aquarium plants, try pruning them back once in a while – you can either discard the cuttings or transplant them elsewhere in the tank. Consider replacing fast-growing species with slow-growing species or introduce a few fish that tend to feed on aquarium plants. You should also check your tank setup to determine whether your lighting may be more intense than necessary. You may also want to cut back on the amount of food you are offering your fish because uneaten fish food will simply accumulate at the bottom of the tank and provide nutrients to fuel excess plant growth.
Black Algae Covering Plants
Many aquarium hobbyists are faced with the problem of their plant leaves turning black, but some fail to realize that the problem may not be with the plants themselves – it may be that dark growths of algae have covered the plant leaves rather than the leaves themselves turning black. In cases like this, the problem is often caused by an excess of phosphates in the tank. The three nutrients essential for plant growth are nitrogen, phosphorus and potassium – if one or more of these nutrients is available in excess, it could cause problems.
In the case of excess phosphates, photosynthesis may occur at a faster rate than usual which could contribute to excess algae growth. High phosphate levels are common in tanks that are poorly maintained, especially when aquarium lighting levels are kept too low. The key to dealing with this issue is to perform a large water change and to establish then keep a routine maintenance schedule. Replace your filter media on a monthly basis and replace 15% to 20% of your tank volume once a week. This should help to keep your phosphate levels under control, thus limiting the growth of algae in your tank and on your live plants.
Holes in the Leaves
If your plants start to develop small holes in the leaves that eventually progress to the total disintegration of the plant, you could be dealing with a case of Crypt rot. This disease primarily affects plants belonging to the Cryptocoryne genus, hence the name Crypt rot. In many cases, this disease develops when water parameters in the tank change too quickly – these plants do not do well with sudden changes in temperature, lighting, or water chemistry. Even if your plants seem to die back completely, as long as the roots remain healthy the plants will come back once conditions in the tank stabilize. To encourage this, perform regular water changes to maintain high water quality in your tank and try to keep the water parameters as stable as possible. If you do these things, your plants should eventually grow back.
Overview of Plant Problems
In many cases, problems with aquarium plants are easy to diagnose – use the chart below to quickly diagnose whatever problems you are experiencing in your tank:
| Symptoms Exhibited | Likely Cause |
| Leaves turning yellow or red | Nitrogen deficiency |
| Leaves turning brown/black, plants dying | Excess phosphate |
| Old leaves developing yellow spots, new leaves yellow on edges | Potassium deficiency |
| Old leaves developing yellow spots, veins staying green | Magnesium deficiency |
| Yellow spots developing on veins, margins, and tips of leaves | Zinc deficiency |
| Plants failing to grow properly, white deposits on new growth | Carbon dioxide deficiency |
| Leaves yellowing from the tip then become transparent | Iron deficiency |
A planted tank is not significantly different from a standard freshwater tank but there are a few things you need to be aware of if you want to succeed. Keep in mind that plants are photosynthetic organisms which means they require light as an energy source to survive. Without adequate lighting and proper nutrients, your live plants will never thrive. Do yourself and your fish a favor by setting up your planted tank properly the first time, then you will be less likely to experience these common issues.