While some plants are supposed to be easy to keep, you might find yourself struggling with melting yellow leaves or a general lack of growth. There are a few factors that go into successfully growing and maintaining freshwater plants, including lighting, substrates, water flow, and nutrients. Nutrients can be confusing to test and understand in the scope of your freshwater tank, but luckily, some products make correct dosing easy for the best life and color out of your plants.
Keep reading to find out everything you need to know about the micro-and macronutrients in your tank and how to keep your freshwater plants happy and healthy!
What are plant fertilizers?
Plant fertilizers are typically concentrated liquids or powders of one or more nutrients that are needed by plants in order to photosynthesize and ultimately grow and reproduce. Nutrients are usually brought into freshwater tanks via fish food, fish waste, substrates, and water changes. However, if the tank has a decent amount of plants and/or nutrient-demanding plants, these inputs might not be sufficient for certain types of plants to complete the processes needed. As a result, hobbyists turn to fertilizers to help with that nutrient deficiency.
What nutrients do aquarium plants need?
Aquarium plants are very similar to terrestrial plants and require most of the same micro-and macronutrients to thrive. Micronutrients, also known as trace elements, are usually inputted into the aquarium system by way of tap water and substrates and outputted by water changes and physiological processes. These micronutrients include:
- boron (B)
- zinc (Zn)
- manganese (Mn)
- iron (Fe)
- copper (Cu)
- molybdenum (Mo)
- chlorine (Cl)
On the other hand, most macronutrients are from fish food, fish waste, and decomposition; some are also brought in by way of tap water but they are mostly derived from organics. These major macronutrients include:
- nitrogen (N)
- phosphorus (P)
- potassium (K)
Secondary macronutrients include:
- calcium (Ca)
- magnesium (Mg)
- sulfur (S)
Depending on plant species, nutrients are taken in through leaves, stems, roots, or all of the above. Each of these nutrients plays an important part in the plant’s survival and ability to grow and eventually propagate. However, even though both micro-and macronutrients can come in through tap water, some hobbyists need to buffer levels by way of a fertilizer.
Are liquid, dry, or root tablet aquarium plant fertilizers better?
Some aquariums don’t need extra nutrients to thrive. Some only need specific nutrient supplements while others need an overall boost of both micro-and macronutrients. The only way to find this out is by routinely checking water parameters and watching how nutrient import and export happens in the tank.
Out of liquid, dry, and root tablet fertilizers, dry fertilizers seem to be the most cost-efficient and customizable type of fertilizer. Many liquid fertilizers include one or more nutrients in an all-in-one bottle while dry fertilizers might come in nutrient-specific pouches; dry fertilizers can be especially helpful if you know the exact nutrient missing from your tank. With dry fertilizers, you also have the ability to manually measure concentrations instead of liquid fertilizers that cannot be as precise. Because of the high concentration of dry powders, dry fertilizers are also cheaper over time.
There is some discussion about whether liquid fertilizers or root tablet fertilizers are better, and hobbyists haven’t seemed to make a concrete decision. It has been argued that deeper-rooted plants will do better with root tabs while floating plants and more superficial species will absorb the nutrients through their leaves and stems. Some hobbyists don’t find a difference between the two while others dose them together. What really matters is if you are dosing the correct nutrients at the right levels and keeping a balance in the system.
It should be noted that while root tabs are just as acceptable to use as dry or liquid fertilizers, it can be difficult to gauge levels at first as the tabs are designed for slow release.
How often do you need to fertilize your aquarium plants?
You will need to fertilize your aquarium plants as much as needed. There is no specific or guaranteed schedule for any tank, even if the product gives a recommendation; for the most part, you will need to customize your own routine to keep nutrients balanced in your tank. In general, all-in-one liquid fertilizers will recommend a given schedule, usually something like two dosings every week with a water change at the end.
With that being said, there are two main ways to determine how often and how much you need to fertilize your tank: the estimated index (EI) method and the perpetual preservation system (PPS-Pro/Classic).
Estimated index (EI) method
The EI method requires dosing more nutrients (micro-and macronutrients) than your plants need, but not so much that can be taken advantage of by algae. This method is recommended for most planted tanks and works best for beginners.
This method can seem counterintuitive at first. Excess nutrients lead to algae so why would you want to purposely introduce more nutrients than are needed? This statement isn’t fully true, and algae growth is more so caused by an imbalance of nutrients, lighting, and carbon dioxide than excess nutrients.
The EI method works on a 7-day schedule where micro-and macronutrients are alternated each day to prevent reactions between the nutrients, namely between iron and phosphate. For example, macros may be dosed Monday, Wednesday, and Friday and micros may be dosed Tuesday, Thursday, and Saturday. On Sunday, a 50% water change is needed to remove excess nutrients from the water column and to let the system rest for a day.
The amount of fertilizer needed each day will depend entirely on the species of plants being kept, lighting, carbon dioxide levels, source water, and other parameters. While this might seem intimidating for beginners at first, the EI method is the best option for high-tech tanks with more demanding species.
Perpetual preservation system (PPS-Pro/Classic)
The PPS-Pro dosing method works on the idea of measuring exact nutrient inputs and outputs, allowing for your aquatic plants to only have the nutrients needed for the day. Once perfected, this method can limit the amount of tank maintenance and overall water changes that need to be done and can lead to a self-sustaining and self-regulating system.
In short, the PPS-Pro method requires measuring out specific amounts of micro-and macronutrients and adding them both to the tank every day. The amount that is needed for this balance needs to be carefully monitored through regular testing. PPS-Pro can be difficult to monitor as nutrient uptake can change daily based on growth rate and other factors.
For most hobbyists, this method is much more advanced and that much more demanding for certain nutrients than the EI method, especially with heavily planted tanks. However, once the ratios are perfected, the cost and time given to the tank can decrease substantially.
Do you need fertilizers for your tank?
Most low-tech aquariums do not need fertilizers. As mentioned before, many of the essential nutrients needed for photosynthesis come from water changes, fish food, and general fish waste. However, if you end up upgrading your aquarium light or start injecting carbon dioxide, then you will likely need to keep up with the demands of the plants and start dosing.
The best aquarium plant fertilizers
The best aquarium plant fertilizer will be one that compensates for the nutrient-uptake and overall lack of available nutrients in the source water. It is up to the hobbyist to measure import and export and find the balance between the two.
In this list of aquarium fertilizers, we have considered efficacy, concentration, price, and overall customer satisfaction. Remember that many hobbyists have to try several products before finding the right one, and sometimes multiple fertilizers are needed.
Thrive Planted Aquarium Fertilizer -All in One Planted Tank Liquid Fertilizers – Micro & Macro Nutrient Rich Food for Aquatic Plants – Highly Concentrated for 2500 Gallons of Water – Handy Pump Bottle
- ✅ SPOIL YOUR PLANTS WITH NUTRIENTS: Make your planted aquarium look great and provide your plants with all the essential micro/macronutrients by choosing the NIlocG Aquatics Thrive aquarium plant…
- ✅ TREAT 2500 GALLONS OF WATER WITH EASE: The Thrive highly-concentrated liquid fertilizer for aquarium plants will allow you to treat up to 2500 gallons of water with just a single 500ml pump…
- ✅ KEEP YOUR AQUATIC PLANTS HEALTHY: Ideal for both low and high-tech setups, our water plant fertilizer will not only keep your plants from dying
One of the most popular all-around liquid fertilizers available right now is NilocG’s Thrive Planted Aquarium Fertilizer. This fertilizer comes in two sizes, 500 ml and 2,000 ml, treating 2,500 gallons (9,463.5 L) and 10,000 gallons (37,854.1 L) respectively.
NilocG Thrive combines both micro-and macronutrients that are needed for plant growth; this does mean that copper is included in the ingredients, which some hobbyists might have concerns about overdosing with invertebrates. Many hobbyists have successfully used NilocG Thrive with all types of invertebrates as long as levels are regulated and water changes are maintained.
This fertilizer is packaged in a squirt bottle that is calibrated for 1 pump (2 ml) for every 10 gallons (37.9 L), introducing approximately 6.0 ppm nitrate, 1.1 ppm phosphate, 5.0 ppm potassium, and 0.25 ppm iron. Hobbyists have found the nitrate concentration to be too much at times, leading to algae, stressed fish, and melting plants; however, this is more often due to incorrect tank maintenance than problems with the product.
Otherwise, this bottled fertilizer will last a long time for most aquariums, which is good considering the initial price. It can be difficult to use the calibrated pump and to measure nutrients being added for smaller tanks, and the liquid caught in the pump is often diluted between each use. Some customers have found little to no difference in their tanks from using NilocG Thrive, while others still find deficiencies in certain nutrients.
What we like:
- All-in-one liquid fertilizer for micro-and macronutrients
- Invertebrate-safe even if containing traces of copper
- Long-lasting and high-quality ingredients with packaging that does not require special storage
What could be better:
- Nitrate concentration can be more than expected, leading to algae blooms and stressed fish
- The calibrated pump can be difficult to measure for smaller tanks
- Some hobbyists find no difference with using NilocG and some nutrients are still deficient
Easy Green All-in-One Fertilizer
A close competitor to NilocG Thrive is Easy Green All-in-One Fertilizer, and the two are pretty comparable overall. Easy Green comes in two sizes: 236 ml that treats 2,300 gallons (8,706.4 L) or 1 L that treats 10,000 gallons (37,854.1) but that doesn’t include a pump. Easy Green is also relatively easy to dose and each pump treats 10 gallons (37.9 L) of water.
In comparison, Easy Green and NilocG Thrive are very similar and many hobbyists find similar results between the two. For the most part, micro-and macronutrient percentages are comparable, however, Easy Green does not include copper which might bring some added comfort to shrimp owners.
Easy Green does not need to be stored in any special way, but it is strongly recommended to keep the bottle out of the sun. Otherwise, most hobbyists have success with this fertilizer, though it is noticeably more expensive than NilocG. Some hobbyists have also found clumping at the bottom of their bottles and overall poor pump quality; some algae outbreaks have also been thought to be connected with this product, though this is possible with all fertilizers if directions are not followed.
What we like:
- Two size options for travel size and bulk
- Comparable ingredients and results to NilocG Thrive
- Copper not included for invertebrate consideration
What could be better:
- Poor quality pump
- Some clumping at the bottom of the bottle
Seachem Flourish Freshwater Plant Supplement
- ENHANCER: Seachem Flourish Advance is an advanced formula contains phytohormones, minerals, and nutrients that dramatically stimulate the growth of both roots and shoots in aquatic plants.
- GROWTH: The phytohormones play crucial roles in regulating plant growth in a wide range of developmental processes, including cell division, formation and activity of shoot meristems, induction of…
- ADVANCED FORMULA: With regular use, Seachem Flourish Advance enhances mineral absorption and improves disease resistance. During the first ten to fourteen days after application, Flourish Advance…
One of the most known aquarium liquid fertilizers is Seachem Flourish. However, this might not be the best product for your tank and the previous two alternatives tend to be more trusted across all tank setups. Nevertheless, Seachem Flourish does have its benefits and is widely used by many hobbyists today for micronutrient dosing.
The main problem with Seachem Flourish is that it lacks concentration levels for many of the macronutrients, namely nitrogen, phosphorus, and potassium. Because of this, hobbyists usually need to buy a whole line of Seachem products to compensate for the nutrients missing which can get expensive and confusing over time. One cap (5 ml) is recommended for every 20 gallons (75.7 L) every day, however, most hobbyists dose only a couple of times a week alternating with dosing other nutrients.
Seachem Flourish is usually used with Plant Pack Enhancer NPK, Flourish Iron, and Seachem Flourish Excel; it is important to keep in mind that Seachem Flourish Excel is a liquid alternative for carbon dioxide injection and doesn’t contain any nutrients. Instead, the organic carbon in this liquid will facilitate photosynthesis as long as nutrients are available.
Seachem Flourish can be useful if you are aware of the nutrient concentrations in your tank and know how to make up for them with other products; Seachem Flourish does contain copper and has been known to affect shrimp and other invertebrates.
While extra dosing can become pricy over time, many hobbyists have seen immediate results from their aquarium plants after just a few uses of Seachem Flourish alone. As always, it’s important to understand what your aquarium needs and how often it needs to be dosed.
What we like:
- Readily available in most aquarium stores
- Provides a broad range of micronutrients
- Easy to dose
What could be better:
- Lacks macronutrients and usually needs to be used alongside other fertilizers and supplements
- Copper can affect invertebrates if water changes are not maintained
- Poor-fitting cap and bottle design
- Very expensive over time
Seachem Flourish Tabs Growth Supplement – Aquatic Plant Stimulant 10 ct
- GROWTH TREATMENT: Seachem Flourish Tabs are growth stimulating tablets for plant roots which contain essential trace elements, amino acids, and vitamins.
- VITAMINS: Seachem Flourish Tabs are rich in iron, manganese, magnesium, calcium, potassium, inositol, choline B12, biotin, and other factors that have been determined to be beneficial to aquatic plant…
- NUTRIENTS: When inserted into the gravel, Seachem Flourish Tabs provide direct, time-released fertilization to the plants’ root zone. Nutrients are slowly made available through enzymatic action of…
Seachem Flourish Tabs Growth Supplement is one of the favorite root tabs chosen by aquarium keepers to keep their plants green and growing. This package contains 10 root tabs that are rich in iron, manganese, magnesium, calcium, potassium, inositol, choline B12, and biotin. The best results will be seen when using a gravel substrate.
One root tab is recommended for every 4-6 inches (10.2-15.2 cm) of the radius. It is estimated that a traditional 10 gallon (37.9 L) aquarium will use 6 tabs that need to be replaced every 3-6 months on average. Many hobbyists end up breaking these tabs into smaller pieces for larger distribution.
Seachem Flourish Tabs are often compared to API Root Tabs. Overall, API Root Tabs have a higher macronutrient content, but only offer minimal micronutrients; API Root Tabs do not contain copper for those worried about dosing with sensitive invertebrates. In comparison, Seachem Flourish Tabs have fewer macronutrient levels, but a larger range of macro-and micronutrients overall.
Root tabs are preferred by hobbyists who keep plant species with deep roots and/or those that may not be able to regularly measure and dose fertilizers. Seachem Flourish Tabs are safe for fish and invertebrates, though some hobbyists have found detrimental effects if the substrate is kicked up; these tabs are also very easy to suck up if using a gravel vacuum. Over time, these fertilizers can be expensive for larger tanks, especially if you have a tendency to suck them out of the tank!
Note that many hobbyists usually use root tabs along with liquid fertilizers as well.
What we like:
- Micro- and macronutrient rich with amino acids and vitamins
- Last a few months at a time and can be left in the tank without having to worry
- Safe for fish and invertebrates
What could be better:
- Easy to suck up with gravel vacuum
- Can be harmful if released into the water column in larger concentrations
- Expensive for 10 count pack every few months
NilocG EI BASED NPK + CSM+B
Dry fertilizers might seem intimidating at first, but they can save money and give better control over your tank in the long run. EI BASED NPK + CSM+B from NilocG is designed to make exact dosing easier following the estimative index (EI) dosing method. This package includes 2 lbs KNO3 (potassium nitrate), 0.5 lbs KH2PO4 (monopotassium phosphate), 0.5 lbs K2SO4 (potassium sulfate), and CSM+B (magnesium, copper, iron, molybdenum, boron, manganese, zinc, and “EDA”/ethylenediaminetetraacetic acid).
At an additional cost, 0.5 lbs iron DTPA 11%, 1.0 lb iron DPTA 11%, 0.5 lbs ferrous gluconate, or 1.0 lb ferrous gluconate may be added. While this set of dry fertilizers is sufficient for the success of most aquatic plants, some hobbyists find that they still need to dose extra iron and/or other nutrients.
With the EI method, control over exact doses can be easy given some time to understand what your tank does and doesn’t need. The upfront costs for these dry fertilizers might seem expensive from the start–plus the additional cost of other equipment, like storage containers and measuring spoons–but these powders can last several years with the right conditions.
What we like:
- Additional iron and ferrous gluconate add-ons
- Exact control over dosings for EI or PPS-Pro dosing methods
- Dry fertilizers last a long time
What could be better:
- Learning curve and steep initial costs
- Does not include additional measuring or storage equipment
Can you use normal plant fertilizers in the aquarium?
It depends. If you have full comprehension of the nutrients in the garden fertilizer and know for sure that they are aquarium safe, then you should have no problems; some hobbyists even use organic potting soil for a bottom layer of a nutrient-rich substrate. But for the most part, it’s better to be safe than sorry and just order some aquarium-specific fertilizer.
In return, aquarium water makes some of the best fertilizers for terrestrial plants, so save those leftovers when doing water changes!
There are many aquatic plant fertilizer products available, and it can get confusing. First, it’s important to understand how nutrients are introduced and recycled in the aquarium and how you will need to manage levels through dosing and water changes. Once you’ve figured that out, you will need to decide if you want to try an all-in-one liquid plant fertilizer that needs to be dosed every few days, or dry fertilizers that might be more cost-efficient with the EI method or PPS-Pro method.
Remember that your tank is a living thing and what might work one day for healthy plant growth might not work the next, so always have a comprehensive index of where your tank works best!
If you have any questions about mico- or macronutrients, how nutrient levels are affected in the aquarium or have had success keeping a high-tech planted tank without any fertilizers at all, don’t hesitate to leave a comment below!