Guide to the Planted Aquarium, Part I
Phil Edwards, MS
Phil Edwards, MS
[Author's Note:]This guide was written in response to seeing numerous comments lamenting the lack of a comprehensive "good" and up-to-date guide to planted aquaria. After reading this some folks pointed out that it's probably not so great for beginners so the Beginner's part was taken out. This is now just a Guide to the Planted Aquarium intended for hobbyists of all levels. Some points for beginners will be left in though. I still hope many beginners will get a lot out of the various parts and find clarity where some of us "old folks" had to search through card catalogs and microfiche.
It will be written in numerous parts with Part I being a listing of terms, their definitions, and a brief overview of general planted aquarium concepts and hardware. More detailed discussions of specific topics mentioned here will be posted in the appropriate sub-forum with links included here as they get written. This document is intended as a reference and not something to be digested in one sitting.
The first three sections are definition heavy. If you're looking for something a bit more readable which explains concepts, start with Section IV. Remember, there will be a test.
This is an original work by the author and may not be used in part or in whole, linked to, or otherwise transmitted without written permission of the author and proper reference/citation. (Take a second and ask, I'll likely say yes. I just like to know where my stuff is being used -Phil).
Part II, Nutrients and Nutrient Supplementation- http://www.plantedtank.net/forums/1...nts-nutrient-supplementation.html#post9960202
Part I, Section I - Technical Terms, Acronyms, and Their Definitions
Section I addresses scientific/technical and general aquatic chemistry related terms commonly or semi-frequently used (and misused) in the hobby. It is not expected that every aquarist, particularly beginners, use or understand all terms listed below. Many of the terms listed are of an advanced nature used in discussion of specific aspects of planted aquarium keeping and are included for completeness. Where possible, the technical definition will be put first with common-use definitions or explanations following. Rather than listing terms alphabetically, terms are grouped by general concept to make relating those concepts and terms easier.
pH- The negative log of the power of Hydrogen protons (Hydronium ions) in a solution. The pH scale ranges from 0 to 14 where 7 is neutral. Lower than 7 is acidic and higher than 7 is basic. In general terms pH describes the acidity or basicity of water. Alkaline is commonly used to in the aquarium hobby to refer to water with a pH greater than 7 but is something of a misnomer, see Alkalinity below.
KH- Carbonate Hardness. Measured on a degree scale (dKH), KH quantifies the concentration of Carbonate (CO32-) and bicarbonate (HCO3-) in a solution.
Buffering Capacity- The ability for a solution to resist acidification. This is commonly used interchangeably with KH and Alkalinity. It's more of a qualitative rather than quantitative term.
pH/KH/CO2 relationship- The relationship between KH, pH, and the amount of CO2 in solution. Addition of CO2 to water creates carbonic acid (H2CO3) which acidifies the water. Comparing pH with KH allows for calculation of CO2 concentration in solution. The relationship is only valid when no material or compounds which reduce pH are present.
GH- General Hardness. Typically measured on a degree scale (dGH) of calcium (Ca2+) and Magnesium (Mg2+) in water. Can also be measured in ppm.
Alkalinity- The total capacity for a solution to neutralize an acid (resist acidification). Total Alkalinity (actual Alkalinity) is comprised of all basic ions in the water; carbonate, bicarbonate, phosphate, Sulfate, etc. Carbonate (CO32-) and bicarbonate (HCO3-) are typically at much higher concentration than the other ions in solution so Alkalinity is commonly used to refer to KH.
ppm- Parts-Per-Million; the concentration of one part of the solute being measured in one million parts solvent relative to the amount of solute. Typically used to measure concentration of plant nutrients. Commonly used interchangeably with mg/L. 1 milliliter is one one-millionth of a liter as is 1 milligram one one-millionth of a kilogram. 1 milliliter of water has a mass of 1 milligram and so 1 liter of water has an equivalent mass of 1 kilogram, allowing mg/L measurements.
mg/L- Milligrams-per-Liter. This is a common means of quantifying the concentration of a solid solute in a liquid solvent. For every liter of solvent (water) there are XYZ milligrams solute. Typically used to refer to the amount of plant nutrients in the aquarium.
meq/L- Milliequivalents-per-Liter. Another means of quantifying the concentration of a solute in solution. The meq refers to the past use of the term Equivalent multiplied by 0.001 to make numbers easier to work with since Equivalents as a measure can be large numbers.
Qualitative- A subjective comparison. “I like cake more than pie.”
Quantitative/Quantifiable- A measurable amount or comparison that can be described numerically. “I added 20 ppm nitrate to my 80 gallon tank.”
Solvent- Any material which will dissolve certain solutes. In aquariums this is typically water.
Solute- Any material which will dissolve in certain solvents. In aquarium these are typically CO2 and fertilizers.
Solution- The mixture of a solvent and a solute or solutes. Commonly used to describe the amount of a chemical in water. For example “I made a fertilizer solution” or “the amount of XYZ in solution”.
Element- A naturally occurring or man-made material in its pure (non-ionic) form. Calcium, magnesium, nitrogen, phosphorus, and potassium are all elements.
Molecule- An electrically neutral combination of two or more atoms held together by electrical/covalent bonds (shared electrons). Sodium Chloride (NaCl) is a molecule.
(Chemical) Compound- A material consisting of two or more atoms held together by various types of chemical bonds. Pure water (H2O) and Glucose (C6H12O6) are compounds.
Ion- An atom or compound with a positive or negative electrical charge. Elements are frequently found in ionic form in solution such as ionic Iron (Fe2+) and ionic Calcium (Ca2+).
Cation- An ion with a positive electrical charge, ie Ca2+
Anion- An ion with a negative electrical charge, ie phosphate (PO43-).
Salt- For the purposes of this document a salt is defined as the combination of two or more ions, typically one or more cations and an anion, into a stable molecule. Magnesium Chloride (MgCl2) and potassium nitrate (KNO3) are salts.
Carbohydrate- An organic compound consisting of various combinations of C, H, and O. Plants use carbohydrates as an energy source as well as structural materials. Glucose and starches are examples of energy source carbohydrates and cellulose and lignin are structural carbohydrates.
ATP- Adenosine Triphosphate. Molecule used as the source of energy for aerobic metabolism.
NADPH- Nicotinimide Adenine Dinucleotide Phosphate. Used as the reducing agent in the dark cycle of plants to fix carbon and form glucose. Also used in the reduction of nitrate into ammonia.
Mole (mol)- 6.022 x 1023 (6,022 with 20 zeroes following it) units of a quantifiable item. A mole of humans would be 6.022 x 1023 people. Relates to aquariums via PAR/PPFD.
Biochemical- Chemical processes which occur in all living things. Photosynthesis is a biochemical reaction.
Geochemical- Chemical processes which occur in or on the earth and do not include biochemical reactions. Ground water dissolving the rock it flows through is a geochemical process.
Biogeochemical – The combination of biological and geological processes in which both living and non living things play a part. The global carbon cycle is a biogeochemical process.
Oxidation- The scientific term for a chemical losing an electron.
Reduction- The scientific term for a chemical gaining an electron.
Aerobic- Metabolic processes in which oxygen is used to oxidize substances. Typically used in aquatics to refer to an environment with sufficient oxygen to meet the metabolic needs of the organisms within.
Anaerobic- Metabolic processes which proceed without oxygen. Typically used in aquatics to refer to an environment lacking in, or devoid of, oxygen.
Oxic- The scientific term used to describe environments which have enough oxygen to support aerobic metabolism.
Hypoxic- The scientific term used to describe environments with low levels of oxygen.
Anoxic- The scientific term used to describe environments devoid of oxygen.
TDS- Total Dissolved Solids. The quantification of all dissolved organic or inorganic solutes in a solution. Solid particles small enough to pass through a filter with a 2 micron pore size are usually included in TDS. Typically measured by specific conductivity in units of µS/cm (microSiemens per centimeter).
Inorganic- Typically defined as chemical compounds that lack Carbon or certain types of carbon bonds. Common examples are nitrate, phosphate, Sulfate, etc. However, carbonate and bicarbonate are considered inorganic as they are produced naturally through geochemical reactions.
Organic- Typically defined as chemical compounds containing carbon and/or chains of carbon. Glucose, chlorophyll, proteins, oils/fats, and humic/tannic acids are organic compounds.
Substrate- Strictly, any surface that living things can grow on. In aquariums substrate typically refers to the solid material(s) on the bottom of the tank into which plants are inserted.
Labile- Easily accessed and/or broken down. Typically used to refer to organic compounds such as proteins, oils/fats, and acids. Humic and tannic acids that leech from new wood are labile.
Recalcitrant- Not easily accessed and/or broken down. Typically refers to organic material or an inorganic matrix which is left over after labile materials have been mineralized or dissolved. The gas which accumulates in CO2 reactors is called recalcitrant gas.
Mineralize- The breakdown of labile organic materials in soil into forms which are available to plants. In the aquarium hobby this generally refers to the saturate-dry-saturate-dry cycle of preparing soil as a substrate amendment. It also refers to the breakdown of organic particles in the aquarium and filter, though it is not commonly used in this context.
Absorption- The acquisition and incorporation of dissolved materials into an organism. Plants absorb dissolved nutrients.
Adsorption- The process of dissolved materials attaching to the surface of a an electrically charged particle. Dissolved organic compounds adsorb onto activated carbon.
CEC- Cation Exchange Capacity. The number of exchangable cations per dry weight that a soil is capable of holding at a specific pH value and are available for exchange with an aqueous solution. In aquariums this is commonly used to refer to the substrate rather than soil as used for terrestrial horticulture. CEC is a generally unnecessary property in aquariums as water isn't draining through the substrate and leaving the system as in terrestrial horticulture. As a substrate property, a high CEC is useful when mineralizing soil as it helps to retain Ca, Mg, and K during the mineralization process.
“Organics”- A colloquial catch-all term for the conglomeration of all dissolved and particulate organic materials in an aquarium. It doesn't differentiate between types of compounds/materials and has no practical means of measure, whether qualitative or quantitative. Typically used as “Your organics are high” when certain algae start growing or water clarity is reduced.
DOC- Dissolved Organic Carbon/Compound. The total amount of organic compounds dissolved in a solution. Typically measured in ppm. DOC is the result of the physio-chemical breakdown of physical material containing organic material (food and feces) or excretion of organic compounds (phytochemicals, etc)
Phytochemical- Chemicals produced and exuded by plants. Typically organic compounds such as acids or poisons. Nicotine is a phytochemical.
POC- Particulate Organic Carbon/Compound. A solid and undissolved organic material. Feces, uneaten food, and dead leaves are examples of POC.
BOD- Biological Oxygen Demand. The total amount of dissolved oxygen required for aerobic organisms to break down organic materials in a given amount of time. Quantified in terms of milligrams of oxygen consumed per liter over a given period of time.
This has commonly been referred to as “aerobic” in the aquarium hobby and is the reason people use aerators to increase oxygen concentration in their tanks. If BOD exceeds available dissolved oxygen then the system will become hypoxic and eventually, anoxic. BOD is primarily important in planted aquaria with soil amended substrates aka “Walstad Method” or “MTS”. BOD in soil amended substrates effects biogeochemical reactions which determine the oxidation state and availability of certain plant nutrients.
COD- Chemical Oxygen Demand. The total amount of dissolved oxygen required in chemical oxidation reactions. This is usually used in association with organic material which is assumed to be able to be oxidized into CO2. It is typically measured in mg/L, where mg is the amount of oxygen consumed per liter of water. Along with BOD, COD in soil amended substrates effects biogeochemical reactions which determine the oxidization state and availability of certain plant nutrients.
ORP- Oxidation-Reduction Potential. A measure of the tendency of chemicals to gain electrons and, as such, be reduced. In aquariums ORP is commonly used as a proxy for the concentration of oxygen in the water.
Redox Potential- See ORP. Measured in Volts of milliVolts on a negative scale with zero (0) being low and very negative being high. As aquatic soils and aquarium substrates become increasingly anoxic, elements in the substrate are more likely to be reduced.
Reduction-Oxidation (Redox) Reaction- The chemical reaction in which one chemical loses an electron to another chemical. The donor is oxidized and the receiver is reduced.
Photoperiod- The amount of time light illuminates plants for the purposes of photosynthesis. “I have an 8 hour photoperiod.” would mean the aquarist has his or her lights on for eight hours.
PAR- Photosynthetically Active Radiation. A measure of the amount of light energy available for photosynthesis measured in Watts-per-square-meter (W/m2).
Photosynthetic Photon Flux Density (PPFD)- In recent years quantifying the number of photons in the 400-700 µm range (spectrum of light used in photosynthesis) colliding with a known area over a given time, PPFD, has been used. Typical PAR meters used by hobbyists these days measure PPFD rather than the original W/ m2 PAR measurement. PPFD is quantified in moles or micromoles of photons per square meter per second (µ)mol/m2/sec.
CRI- Color Rendition Index. Strictly, CRI is the ability of a light source to accurately reveal the colors of an object in relation to an ideal or natural light source on a continuum with 100 being perfect color rendition. CRI is commonly misused when referring to color temperature.
Color Temperature- A means of describing the appearance of light using a Kelvin scale ranging from 1,000 to 10,000. The lower the rating the more red “warm” the light appears. The higher the rating the more blue “cool” the light appears. Natural sunlight has a Kelvin rating of 6500 to 6700 accounting for variance in angle of illumination relative to the point of measurement.
Emersed/Emergent [Growth]- A means of growing aquatic plants above water hydroponically or in saturated soil to capitalize on the high concentration of CO2 in the atmosphere. This is an industry standard for suppliers of aquatic plant nurseries. It is commonly used by hobbyists as a low-cost method of maintaining plant collections or get plants to flower for identification.
Submersed/Submergent [Growth]- The form of an aquatic plant when grown underwater. Also used to generally describe populations of aquatic plants, aka “Submersed Aquatic Vegetation.
Stomata (plural)- Openings in leaves through which gas exchange occurs.
Obligate- Requiring a set of conditions to live. Vallisneria obligate aquatic plants.
Facultative- Able to live under multiple conditions. The majority of aquarium plants are facultative in that they can grow above and below water and generally require emergent growth for some portion of their life cycle; typically for reproduction.
PMDD- “Poor Man's Dupla Drops”. A formula developed in the mid-90s by Paul Sears and Kevin Conlin for making a nutrient solution similar to the original, and expensive, Dupla Drops sold by the German company of the same name. The original intent of Sears and Conlin's research was to develop a method of fertilizing plants while limiting P in the system, as it was commonly thought that P was a major contributor to the proliferation of algae at the time.
PPS and PPS Pro- Perpetual Preservation System. A system of nutrient supplementation developed by a hobbyist named Edward designed to maintain certain concentrations of plant nutrients in the aquarium based on an aquarium's unique needs. As described, the method requires regular testing to determine system-specific consumption rates do then come up with a regular dosing regimen. The original PPS was intended to be used in aquariums which receive no to few water changes. PPS-Pro was later developed to reduce or do away with the need for regular testing.
EI- Estimative Index. Described by Tom Barr, EI is a method of nutrient supplementation based on the use of dry inorganic nutrient salts and/or liquid solutions. The concept behind EI is providing all plant nutrients in excess of their needs to prevent nutrient limitation and thereby maximize plant growth. Rather than determining system-specific dosing like PPS, the EI method uses general amounts of each nutrient based on ranges of tank volume to determine dosing amounts. For example, adding 1 teaspoon of KNO3 to a 75 to 90 gallon system to achieve an estimated concentration of NO3-.