In planted circles, aquarists quickly learn that nutrient dosing is important. And it is. However, many fall prey to the tendency to over extend this fact to see every change (or non-change) in growth/ form / color as solely linked to nutrients, and overwhelmingly in terms of some deficiency or imbalance.
This is partially due to availability bias: on public forums, list any plant defect and one invariably gets a ton of well-intended responses that focus on the nutrients that are presumably lacking. Forums are the number 1 spot for availability bias and group thinking, and it is easy to blame nutrients for plant problems. However, plants are affected by a huge number of non-nutrient related issues that can lead to yellowing/stunted leaves. When folks think that it is nutrient related - especially when they are already dosing adequate amounts, then they keep looking for wrong causation, which cause them to never solve their problems.
The result is often a never ending circle of tweaking NPK and Iron dosing values, hoping to find the 'secret ratio' that finally gives the desired quality of plant growth as well as the complete disappearance of all algae issues. But no amount of fertilizer or water parameter tweaking alone will give a great tank as those are far from the only things that impact tank outcomes. I've seen experienced aquarists spend years running around the same circle, hoping to find some magic combination in their dosing ratios - they end up as somewhat better chemists, but their tanks look no better.
My tanks often measures much lower nutrient values than people expect. Nitrate/NO3 levels in my water column often bottom out or sit below 5ppm. This does not mean that my plants are under-fed; it just means that the residual level in the water column is low. Folks often mistake residual water column levels for what is available to the plants.
Nutrient tunnel vision also stems from the widespread use of 'deficiency charts' which tend to oversimplify the cause, and over-focus on nutrients. See what the industry experts say:
"It is a chronic newbie-intermediate urge to get focused on deficiencies, even when they're following EI (!!). I used to think all my issues were lack of something or another and when you find charts like this, it temporarily confirms existing biases. You figure your issue is K deficiency. You add K2SO4 but nothing gets better. Then what? Then it's time to focus on other stuff. I've found many clever ways to kill and stunt plants, especially Rotala and Ammannia. Deficiencies are low down on the list. Poor maintenance and poor CO2 are big reasons." - Vin kutty
"Grow the plants, not the deficiencies. The method is deceptive as it is simple."
- Tom barr
The worst thing about this particular chart is that the picture for magnesium deficiency is wrong. The correct depiction of Mg deficiency is actually the opposite; pale/whitish veins coupled with green leaves.
"I find it hard to name a factor besides Nutrients & CO2 that can cause changes to plant growth form or algae."
|"I spend more time talking about my water parameters on online forums, than working on my tanks... What do you mean by working on my tank?"||"I have experimented with 1001 ways of dosing; different ratios, types of iron chelates, trace mixes, and yet my plants are no better than folks that just seem to follow simple fert regimes."|
If those 3 statements resonate with you, you are not alone, as most hobbyists easily fall into the trap of nutrient tunnel vision.
The reality is that nutrient dosing, while important, is only one part of having good plant growth and an algae free tank. Tank results are largely dependent on other human-related maintenance factors that have nothing to do with nutrients or water parameters.
The nutrient dosing approach for my own tanks is kinda stupidly simple. I dose a standard dosage of APT complete, and enrich the soil periodically - yet I can grow any commercially available variety of aquatic plant - and often grow it better than most folks. This is largely because I spend less time shadow boxing imaginary nutrient issues, more time on improving my horticulture skills.
Nutrient deficiencies are hard to spot accurately but actually pretty easy to rule out.
The easiest approach is to check that you have met the baseline values for the main nutrients to start with. The nutrient dosing page covers a variety of methods of how this can be achieved and what levels are reasonable. These levels have been tested by expert aquarists over the years and most tanks fall within the ranges.
It takes quite a sustained lack of a specific nutrient to induce an actual deficiency.
Find out what is in your tap water (details on understanding water parameters here) and find a regular method of dosing fertilizers. If you have followed the baseline ranges detailed in the nutrient dosing guide - it is actually pretty difficult to get deficiency symptoms for most tank setups. You will never see the deep deficiency symptoms detailed in "plant deficiency charts". For most plants, if a certain nutrient is present but in small amounts, the plant merely down-regulates growth to compensate.
Aquatic plants would not survive long in nature if it required them to be constantly marinated in a highly concentrated fertilizer mix - most natural waters are very lean nutrient-wise compared to the levels we use in our tanks. The popularity of soil bases in modern aquariums, similar to in nature, also forms a backup reserve on which plants can draw from.
There are approaches to move from nutrient levels from a state of "nutrient sufficiency" to more "optimal levels" to get better form/color/health, these will be covered in later newsletters. For the purposes of avoiding efficiencies for 98% of the tanks out there, the above method will be more than adequate.
Tom barr cites CO2 as the number 1 cause of plant issues by far - because it is difficult to check, many folks just assume levels are good because they seem to be injecting "a lot". In reality, depending on injection methodology, tank dimensions, flow setup and other factors, CO2 saturation rates can vary tremendously.
50% of plant mass is carbon while the most used "nutrient", Nitrogen, only makes up only about 1.5% of plant mass. Yet most hobbyists only have poor estimates of what their actual CO2 levels are. The same hobbyist can argue all day whether 15 parts per million NO3 is better or 20 parts per million NO3 is better. CO2 assimilation is light dependent; and plants can't utilize stored reserves (which they can do with NPK). NPK is commonly available through fish/soil/tap water, whereas CO2 has to be introduced, circulated, and degases naturally if injection is stopped while other minerals accumulate.
HC is a pretty good indicator of CO2 levels near the substrate zone. It works much more reliably than any drop checker.
Key steps in improving CO2 levels:
When the environment changes for a plant, there will be a period of adaptation as the plant reprograms its cells to optimize resources available in the new environment. When light becomes insufficient for example, we see stem plants channel energy into growing longer stems in order to reach the light. Many other changes occur at the cellular levels that are not so visible to aquarists. However, this often manifest as a deterioration of older leaves as the plant channels energy to new growth - new growth that is optimized to the new environment. New growth that is optimized for environment is robust and more resilient towards algae as well, while the older deteriorating leaves can develop algae.
There are two important angles to this. The first is that you should keep the overall environment of the tank stable, so that the plant does not keep re-programming its cells to match what is available. This means keeping CO2, water parameters and other nutrient variables consistent. New hobbyists in search of the holy grail of parameters often fail at this because they keep changing parameters before plants have time to adapt. Plants can take up to 2 to 3 weeks in faster growth systems to adapt fully to regime changes. While in slower growth systems or slower species (such as Bucephalandra), adaptation can take up to a couple of months to fully play out.
The second is knowing that old leaves on plants do not heal - this is so even if your 'new environment' has better variables than the old. If plants are adapting to new tank conditions well, new growth should be well colored and algae free but old growth will deteriorate and eventually you need to cut and replant the new portions of the plant, discarding the older deteriorating portions. The bigger the changes in environmental variables, the more plants have to adapt and the faster they will discard older leaves as cells there are not optimized for the current environment. Unlike humans that can heal, plants adapt by constantly growing new leaves and discarding older, less optimized growth.
If you aim at preserving the maximum number of older leaves on a plant in the long run - keep the environment stable so that there are no adaptation changes.
It is not common to see large patches of sensitive plants like Hygrophila sp. Chai in hobbyists tanks. Most folks run their tanks in an unstable manner, which leads to premature deterioration of the older leaves. So although their Chai patch produces new leaves, its countered by the degradation of older growth - thus the patch remains sparse. For plants such as these, they are a great test of long term stability of the tank.
Some plants such as Limnophila aromatica, Ludwigia sp red, and Myriophyllum 'Guyana' can be trimmed into neat bunches and tolerate slight over-crowding. Other plants may prefer more space to grow into good form. There isn't a blanket rule - but by observing the species in your own tank grow over time, its pretty easy to figure out.
Substrate is a useful tool for those who know how to manage it, a bane for those who do not.
Oxygenation is as important for planted tanks as carbon dioxide. A successful planted tank is build upon an aggregation of small optimizations and effective choices.
Algae is a symptom, not just something to get rid of- Dennis Wong
If you have algae attached to plants, it indicates that the plant is under some sort of adaptation stress / not growing well. The question to ask is how to improve the health of that particular plant - removal of algae is a secondary concern. Folks often overly focus on tank parameters, but miss direct signals from the plants such as this.
Water changes are not enough - clear up detritus by siphoning if you do not want algae. Perfect parameters alone do not make an algae free tank.
Adopt a robust nutrient dosing regime in your tank, but once you have that, spend time in working on the other aspects of tank upkeep. Horticulture skill requires practice, experimentation and observation; and the upkeep of planted tanks is so much more than hitting specific water parameter numbers.
Though there are numerous angles to look at things - most of it boils down to observation of plant, fish and other happenings in the tank environment. Plants and livestock often give pretty direct feedback as to what is happening in the tank and changes to tank water quality.
Hopefully, this article has shown a glimpse of the multitude of other factors that one can consider when analyzing plant issues.