in accordance with Liebig's law of minimum.
"When two or more factors limit growth, addition of just one will have little effect. The provision of both will have a much greater influence"
Marginally low in a number of nutrients, one unavailable nutrient limits overall growth, over time.
Increase supply of that limiting nutrient, even slightly, increasing the demand for nutrients and another nutrient, the next unavailable, becomes limiting.
C, H, O, N, P, K, S, Ca and Mg
Mobile or non mobile elements.Carbon (Nonmobile)
Mobile nutrients can be reclaimed from old leaves and used to produce new growth.
Nonmobile nutrients can not and nutrient deficiencies show up in new growth.
✒ CO2 and Light
✒ 35-40 mg/L
✒ DIY CO2
✒ Non CO2 methods
✒ Dissolved organic carbon (DOC).
After ten days of CO2 supplementation there should be a noticeable increase in growth.
Environments with elevated CO2 will require non-limiting macro-nutrient and trace due to the vigorous nutrient uptake from the plants. Moderately lit aquatic environments with ample CO2 have 4 ~ 5 times greater growth then low or inconstant CO2 levels. Under higher lighting, CO2 is essential or plants quickly becomes CO2 limited, leading to growth deficiencies and unwanted algae.
Hydrogen is necessary for building sugars and building the plant. It is obtained almost entirely from water. Hydrogen ions are imperative for a proton gradient to help drive the electron transport chain in photosynthesis and for respiration.
✒ Barr Report Newsletter (BRN) - Oxygen
✒ Dissolved Oxygen 6ppm
The efficiency of nitrifying bacteria is at it's best when the water is near oxygen saturation and most oxygen concentrations below 3 ppm are not considered healthy. The approximate saturation level for oxygen at 50° F. is 11.5 mg/l; at 70° F., 9 mg/l; and at 90° F., 7.5 mg/l. Impurities added to the water (i.e. salt) or an increase in altitude (above sea level) further decrease these saturation levels.
Energy from respiration drives metabolic processes. In plants these processes include the absorption of plant nutrients (salts) into roots, transport of potassium (K) into and out of guard cells. Other functions: synthesis of proteins, lipids and structural components of plants such as cellulose and other fibers all require O2. Synthesis of storage compounds in stems, roots and seeds also require O2.
Nitrogen (very mobile)
✒ BRN - Nitrogen
✒ Nitrogen cycle.
NO3 ≮ 5ppm
DC Tap water 2ppm
Fish waist, (ammonia / nitric acid).
Ca++ ≮ 10ppm
DC Tap water 44ppm
✒ BRN - Calcium
Thought to enhance uptake of N-NO3. Calcium deficiency can cause stunting of the terminal buds; developing roots, distorted new growth (twisted, bent, maybe cupped leaves) black spots/white leaf margins and impaired root function. Some sources of calcium are; Gypsum plaster/Plaster of Paris (CaSO4.1/2H2O), calcium sulphate (CaSO4) and Calcium Chloride Dihydrate (CaCl2.2H2O).
Mg++ ≮ 3
DC Tap water ~9ppm
✒ BRN - Magnesium
Magnesium is the only mineral constituent of the chlorophyll molecule accounting for near 20% of total Mg in plants. Magnesium serves as a structural component necessary for protein synthesis. Most reactions involving phosphate transfer specific to ATP require this element, as well as, the activities of several other enzymes. As an example, insufficient magnesium can restrict RuDP carboxylase and CO2 assimilation. Deficiency symptoms often result in leaf distortion for this reason. Other symptoms include interveinal chlorosis of the lower leaf, in which the veins remain green; advancing to uniform pale yellowing of the leaf, to brown and necrotic.
✒ GH & KH
My tap water's total hardness (GPG), 5.3 - 11
Alkalinity is 37 - 111ppm
PO4 ≮ 0.4ppm
DC Tap water ~2ppm
Fish waist/Fish food
- A useful animal cell buffering agent, a component of DNA, RNA, ATP, phospholipids, bulbs and flowers.
- GSA, indicates high levels of light, low phosphate and/or low CO2.
✒ BRN - Phosphorus
✒ False positive for CO2
✒ Limiting plant growth
Potassium (very mobile)
K+ ≮ 5ppm
DC Tap water ~3ppm
Plants can not use phosphate or nitrate when they don't have potassium available.
✒ BRN - Potassium
Sulfate (Moderately mobile)
DC Tap water ~54ppm
✒ BRN - Sulfur
Although sulfur is most often regarded as secondary nutrient,
plant requirements for sulfur are equal to and sometimes exceed those for phosphorus.