Each biological process in a plant is influenced by several nutrients, and the visible failure of a process (turning pale (photosynthesis incomplete), getting holes/tears/fraying (structural problems), discolouration etc etc) is caused by missing one or more of several nutrients. TLDR: everything looks like everything.
Some nutrients have distinct symptoms when absent, or only occur in new growth. Look for idiosyncratic details in the symptoms, and confirm a deficiency by seeing it appear across different species.
Dosing Calculator - https://rotalabutterfly.com/nutrient-calculator.php
Nitrogen (ammonia, urea, and nitrate)
new leave to become smaller and older leaves to start to yellow. This yellow discoloring usually starts at the tips and move to the base of the leaves. This is the plant’s way of using the older leaves as nutrients for new leaves growing in. The new leaves will appear light green.
old leaves turning yellow and translucent, especially starting at the leaf tips
reducing nitrogen is the purpose and effect of water changes?
Although aquatic plants can absorb and use nitrogen in all forms (nitrates (NO3)), nitrites (NO2), ammonia (NH3)), many plant species still prefer ammonium (NH4+). If there are ammonium and nitrates present in the tank, they will always ignore nitrates and take ammonium first. Ammonium is the fastest way of getting nitrogen into a plant’s system. That is why they do not have to spend energy converting it to the form it uses.
Special needs: Duckweed, potamogetons and salvinia showed symptoms first: turning white, undersized new growth. submerged leaves dissolving.
Phosphorous (Phosphates, PO4):
uncommon (phosphates are an ingredient in fish food. If you feed your fish, you are also adding phosphates to your tank)
Colored plants become more pale when PO4 is lacking (differential:Iron).
Tanks with significant amount of livestock generally have quite a bit of PO4. However, tanks with fewer fish may experience a lack of phosphates because you are not adding as much fish food. In addition, phosphate filters may also lower phosphates to where it starts to affect the tank. Adding monopotassium phosphate to a tank will help increase phosphate levels.
These leaves will appear darker than usual, with brown undersides. Leaves will then turn completely yellow with soggy melt-like brown patches. Then, the dying leaves will usually form algae. The new leaves typically grow shorter and may even be distorted. Stems will grow to normal lengths but be much thinner compared to a healthy plant.
amount of potassium the aquatic plant needs is second only to nitrogen
Small pinholes on the leaves, mostly concentrated at the edges and tips. Note: 99% of the time to c02 is blame for pinholes.
Sometimes the edges may appear pale and curl inward.
plants begin to develop holes that are outlined with black or yellow color. The leaves can melt away in the yellow area as well.
Broadleaf water sprite- showed symptoms first: holes, transparency that looked like it was gently crushed, fraying edges. The water sprite frantically grew babies all over the surfaces of every leaf, anticipating falling apart before damage is visible.
Hygrophila- Pinholes in old leaves that multiplied until half of the leaf was perforated free. Resolved with KCI dosing. The water sprite got a little better but still not right.
“plants such as anubias or java fern need lots of potassium to survive” (please note that they say survive, not flourish).
Cheats: KCl (potassium chloride) is sold in grocery stores as a (poison flavoured) salt substitute (No-Salt Salt). A small amount, say 1/8 to 1/4 teaspoon KCl for every 10 gal., should get your plants on their way to recovery. Dose doesn't have to be perfect. To reach your target of 30ppm K you will need to add 4.33 grams (equivalent to 1/2 tsp + 1/4 tsp + 1/8 tsp + 1/16 tsp + 1/64 tsp ) KCl to your 20gal aquarium to yield: 30ppm Potassium
High magnesium inhibits potassium.
Extremely high potassium inhibits calcium
Bullshit: The internet tells me there should be enough in tap water, but how is that even possible, why do I have symptoms despite supplementation.
rare* (*I caused it by dosing potassium higher and higher chasing holes possibly caused by low C02??)
new leaves growing out twisted and stunted
tips of the leaves may wither
Calcium is used in the plant’s cell wall production process and is a crucial component of a structurally stable cell wall. A calcium deficiency may be a result of using soft water or RO water in your planted aquarium
It is recommended to gradually increase your water’s hardness by adding crushed coral in your filter or sprinkling it on top of the substrate.
Cheats: Dolomite (raises alk), gypsum (no ph change)
Dolomite is used in agriculture to neutralize soil acidity (increases water hardness) and supply calcium and magnesium; as a source of carbon dioxide;
Special needs: Hygrophila and amazon sword showed symptoms first: twisting leaves and rippled edges.
Interactions: Extremely high potassium inhibits calcium.
leaves to turn lighter in color while the veins stay dark. This is similar to an iron deficiency, but a magnesium deficiency will be seen in the older leaves. The edges of the leaves may begin to droop. This deficiency is sometimes related to a calcium deficiency. Magnesium is already in most aquatic plant fertilizers, so simply make sure you have a fertilizer regimen.
Key molecule in chlorophyll. (above) Available quite commonly in tap water, but for regions where tap water has no Mg, dosing it regularly is critical. Many commercial fertilizer miss this in their formulation.
Cheats: Dolomite, epsom salt
Dolomite is used in agriculture to neutralize soil acidity (increases water hardness) and supply calcium and magnesium; as a source of carbon dioxide
Interactions: High magnesium inhibits potassium.
Aquarium water is nearly always deficient in CO2. Natural CO2 has already been removed from the water which flows out of our taps at the waterworks, by means of aeration. The aquatic plants hungrily devour the minimal quantities which exist in the aquarium. The available supply is usually insufficient. As a result, stems and leaves appear weak and pale, with no sign of growing power. The plants’ resistance is weakened, algae settle on the leaves. In contrast to natural environments, the natural source of supply is lacking in aquaria. But who wants a centimetres-thick layer of sludge consisting of dead leaves and food residues in their aquarium?
((((So help me jesus, headesk))))
CO2 FERTILIZSATION HAS MANY ADVANTAGES
Part of the CO2 which dissolves in water forms carbonic acid. This means that CO2 can be used to set the pH value (acid content) of the aquarium water to ideal levels for fish and plants, similarly to those which prevail in nature.
Trace elements which are important for plants and fish are taken in more effectively
Unsightly lime deposits are avoided on plant leaves ("biogenic decalcification")
CO2 DEFICIENCY HAS SERIOUS CONSEQUENCES
Stunted and crooked growth
Much too high, unnatural pH values
resulting in stress for fish and an increased susceptibility to disease
Iron and trace element deficiency
Good plant growth = no alga. In aquaria with strong growing aquatic plants, troublesome algae have practically no chance. Nutrients conducive to algae growth, such as phosphates and nitrates, are "absorbed" immediately by the plants. Plant growth starts to flag when CO2 is lacking, however. Surplus nutrients are no longer consumed quickly enough. This is the chance for algae, as they need only the most minimal amounts of CO2.
That’s why a good stock of plants and regular CO2 fertilization are among the most important measures to prevent algae.
Cheats? (unconfirmed efficacy) Dolomite is used in agriculture to neutralize soil acidity (increases water hardness) and supply calcium and magnesium; as a source of carbon dioxide;
Iron (Iron chelates, soils, Fe)
common (it is unstable in water and tends to precipitate out)
leaves will begin to turn a lighter green and the veins will stay the same deep dark green.
Iron is an immobile nutrient and plants cannot transfer Fe from old leaves to feed new growth. Thus a lack of Fe is first seen as the yellowing of new leaves and poor pigmentation in colored plants.
There will not be high enough concentrations of iron in all-in-one fertilizers.
Plants with special needs: (these are both possibly due to being root feeders without appropriate access)
Amazon Sword showed symptoms first: transparency of new leaves
Cryptocoryne: reds became pink and amber, new leaves show chlorosis early. Old leaves develop apathy and the texture of garbage bag plastic.
Lucky Iron Fish experiement??? We’ll see..
Chelated iron pills as root tabs
yellow to white reticulated patches on the leaves.
Manganese has a key role in photosynthesis.
Keep in mind that some species, such as Anubias Pinto or Anubias Nana Petite White, have leaves that naturally have light colored patches and dark veins.
Boron, Copper, Boron: Trace elements. Plants use only tiny amounts of these, but they do affect both plant coloration and growth form. In high speed growth rates of CO2 injected tanks, it is easy to get sub-optimal levels of trace elements. Required dosage is tiny, but should be done regularly.
