Reference

Glossary

Short, plain-English definitions. Each term links to the guides that cover it properly.

1

120 V / 60 Hz: US household mains supply: the US Department of Energy gives 110-120 V at 60 Hz. Buy aquarium equipment in its 120 V / 60 Hz variant: Fluval lists the A202 at 3 W on 120 V / 60 Hz, and Intermatic rates the TN311 at 125 VAC, 60 Hz. Read more: 120 V vs 230 V aquarium equipment

2

230 V / 50 Hz · also 220-240 V: Mains supply in much of Europe and elsewhere. Sicce lists its AIRLIGHT pumps at 230-240 V / 50 Hz only, so they are not for North American outlets. Read more: 120 V vs 230 V aquarium equipment

3

3/16 in airline · also 3/16 inch tubing: The common North American airline size. Danner describes its standard tubing as 3/16 in; Fluval lists 3/16 in (4.78 mm) hose for its A Series pumps. It is not the same as 4 mm metric airline. Read more: 3/16 in vs 4 mm airline tubing

4

4 mm airline · also 4 mm tubing: Metric airline with a 4 mm inside diameter, used by Tetra's CV4 check valve and EHEIM's air100 pump. It differs from 3/16 in airline, so fittings may not seal across sizes. Read more: 3/16 in vs 4 mm airline tubing

A

A-weighting · also dB(A), dBA: A filter that weights sound readings toward what human ears hear, written dB(A). None of the air pump figures we found say whether they are A-weighted, which is one reason figures from different publishers do not compare. Read more: Air pump noise figures, explained
Air outlet · also outlet, port: The nozzle on an air pump where the airline attaches. Tetra says a dual-outlet pump is very loud unless both outlets have airline; Aquarium Co-Op sells single- and dual-outlet pumps. Read more: Air pump flow explained
Air stone · also airstone, bubbler: A porous block on the end of an airline that breaks the air into small bubbles. Tetra notes that tubing, air stones and check valves are sold separately from its pumps. Read more: Do air bubbles add oxygen to an aquarium?, Aquarium air pumps and aeration
Airflow · also air output: The volume of air an air pump pushes out over time, usually given in liters per minute or liters per hour. Real output falls as depth and resistance in the line rise. Read more: Air pump flow explained, Aquarium air pumps and aeration
Airline tubing · also airline, air hose: Small flexible tubing that carries air from the pump to a stone or filter. Danner describes standard 3/16-inch airline; Aquarium Co-Op says all airline eventually hardens in water. Read more: 3/16 in vs 4 mm airline tubing, Airline tubing and check valves
Algae scraper · also glass scraper: A blade or pad on a handle for removing algae from the inside of the glass. Read more: Aquarium maintenance tools
Alkaline battery: A standard 1.5 V disposable cell. EHEIM says its autofeeder must run on alkaline AAs, not rechargeables, and Fish Mate recommends one AA alkaline for the F14. Read more: Automatic feeder not dispensing or clumping, Automatic feeder specs compared
Aquarium test kit · also master test kit: Reagents or strips for measuring water values. API's Freshwater Master Test Kit measures pH, high range pH, ammonia, nitrite and nitrate with seven solutions. Read more: Water-change tools and test kits, Aquarium maintenance checklist
Authorized seller · also authorized dealer: A store a brand names as selling its products. hygger lists its authorized Amazon stores; NICREW calls Amazon its only official online channel and requires proof of purchase from one for warranty. Read more: Buying aquarium gear online: a checklist

B

Back-siphoning · also back-siphon: Water running back down an airline into the pump when it stops, as in a power outage. Aquarium Co-Op says to keep the pump above the water level or fit a check valve. Read more: Air pump above or below the tank?, Which way does a check valve go?
Background noise: The sound in a room before a device runs. FishLab took its readings at night in a room quieter than its meter's 30 dB lower limit. Read more: Air pump noise figures, explained
Backpressure: Resistance an air pump must push against: water depth above the air stone, plus the stone, tubing and valves. FishLab measured output at 10, 20 and 30 inches of depth and reports that depth affected both output and noise. Read more: Air pump flow explained
Barb fitting · also barbed connector: A fitting with a ridged nozzle that grips tubing pushed over it, found on check valves, connectors and pump outlets. Read more: 3/16 in vs 4 mm airline tubing
Battery backup: A built-in battery that takes over when mains power fails. Aquarium Co-Op says its air pump switches to its lithium-ion battery automatically when power is lost. Read more: Battery-backup air pumps, Power outage while you're away

C

Canadian certification mark: A mark such as CSA, cUL or cETL showing a product is certified for Canada. Health Canada says it must be on the product itself, and British Columbia requires one on electrical equipment. Read more: UL vs ETL vs CSA marks on aquarium equipment
cCSAus · also CSA certified: A CSA certification mark valid for both Canada and the US. Intermatic lists the TN311 timer as cCSAus: CSA certified, not UL listed. Read more: UL vs ETL vs CSA marks on aquarium equipment
CE marking · also CE mark: The EU conformity mark. EHEIM's autofeeder manual says its symbol means the unit conforms to EU standards; it is not a North American safety listing. Read more: UL vs ETL vs CSA marks on aquarium equipment
Check valve · also non-return valve: A one-way valve in the airline that lets air out but stops water siphoning back into the pump. Danner says its valves are marked with the flow direction and go outside the water. Read more: Which way does a check valve go?, Air pump above or below the tank?
CO2 check valve: A check valve made for pressurized CO2 lines. Aquarium Co-Op says its standard check valves are for air only and sells a separate stainless-steel CO2 valve. Read more: Which way does a check valve go?
Compartment feeder · also rotor feeder: A feeder with pre-filled compartments, one meal each. Fish Mate's F14 turns a rotor of compartments on a clock and releases each meal over about two hours. Read more: Drum vs compartment fish feeders
Condensation tray · also cover glass: A cover that sits under a light to stop water reaching it. The F14 manual says feeder mounting there is not normally recommended unless an air pump feeds its AIR port. Read more: Automatic feeder not dispensing or clumping
Continuous ammonia monitor · also ammonia badge: A badge that stays in the tank and changes color with free ammonia. Seachem says its Ammonia Alert responds in about 15 minutes to rising and about 4 hours to falling levels. Read more: Free vs total ammonia

D

Decibel (dB) · also dB: A logarithmic unit of sound level. A dB figure means little without the distance and setup: FishLab read its meter in air 6 inches from each pump. Read more: Air pump noise figures, explained
DEHP · also di(2-ethylhexyl) phthalate: A phthalate plasticizer used in some flexible PVC. EPA released its final TSCA risk evaluation in December 2025; Aquarium Co-Op's black airline carries a California Prop 65 warning for it. Read more: 3/16 in vs 4 mm airline tubing
Diaphragm pump: The usual aquarium air pump design: a rubber diaphragm flexes to push air. Tetra says a pump that stops producing air or gets very loud may have a worn diaphragm; Fluval says its A Series diaphragms are EPDM rubber. Read more: Air pump noise figures, explained, Aquarium air pumps and aeration
Dissolved oxygen · also DO: Oxygen held in the water that fish and bacteria use. A 2020 study of 54-liter tanks found fish metabolism, which rose with feeding dose, had the greatest effect on oxygen use. Read more: Do air bubbles add oxygen to an aquarium?
Double feeding: EHEIM's setting that turns the autofeeder drum twice, one minute apart, at a feeding time, for larger portions. Read more: Automatic feeder specs compared
Drip loop: A dip in a power cord below the outlet so water drips off instead of running into the plug. Aquarium Co-Op and JUWEL both tell owners to form one. Read more: Aquarium electrical safety basics
Drum feeder: A feeder with a rotating food drum that tips out a portion each turn. EHEIM's autofeeder is one; it holds about 100 ml and sets the portion with a slider on the drum. Read more: Drum vs compartment fish feeders

E

ETL Listed · also ETL: Intertek's mark showing a product was tested and certified by Intertek, an OSHA-recognized lab, to applicable safety standards. Read more: UL vs ETL vs CSA marks on aquarium equipment, How to verify a UL or ETL listing

F

Faucet adapter: A threaded fitting that joins a water changer to a faucet in place of the aerator. Python supplies a 69HD brass adapter and says some faucets need a MABA or FEBA adapter. Read more: Faucet water changers
Faucet water changer · also No Spill system: A long hose that connects to a sink faucet to drain and refill a tank without buckets, such as Python's No Spill Clean and Fill or Aqueon's 25 and 50 ft changers. Read more: Faucet water changers, Python vs Aqueon water changer
FCC authorization · also FCC ID: US approval that a radio-frequency device meets FCC rules on interference and RF exposure. It is not a shock or fire safety listing. Read more: UL vs ETL vs CSA marks on aquarium equipment
Feeder air port · also AIR port: A connector that lets an air pump blow dry air through a feeder. Fish Mate suggests using the F14's AIR port against condensation; JUWEL says its EasyFeed can connect to an air pump to keep food dry. Read more: Automatic feeder not dispensing or clumping
Feeder capacity: How much food a feeder holds, such as EHEIM's about 100 ml or Aquarium Co-Op's about 200 ml. It is a volume, not a trip length: how long it lasts depends on portions and feeds per day. Read more: Automatic feeder specs compared
Feeding hole: An opening in a tank hood for food. Fish Mate says to sit the F14 over it, or cut a 30 mm (1-1/4 in) hole if there is none. Read more: Automatic feeder not dispensing or clumping
Free ammonia · also NH3, un-ionized ammonia: The un-ionized, more toxic form of ammonia (NH3). Seachem's Ammonia Alert reads it, flagging about 0.05 mg/L as ALERT. Its share of total ammonia rises with pH. Read more: Free vs total ammonia
Free Return: An AliExpress label on some products. Its 2022 terms allow a return within 15 calendar days of receipt, with conditions and regional parts; check current terms. Read more: Buying aquarium gear online: a checklist

G

Gang valve · also manifold: A manifold with several small taps that splits one airline into several lines, each with its own adjustment. Read more: Airline tubing and check valves
Gas exchange: Oxygen entering and carbon dioxide leaving the water at its surface. A 2020 study of 54-liter tanks found oxygen uptake from the air was strongly influenced by water flow and open surface area. Read more: Do air bubbles add oxygen to an aquarium?
GFCI (ground-fault circuit interrupter) · also GFI, ground-fault protection: A device that cuts power when current leaks to ground. An Ontario teachers' union bulletin says school aquarium appliances should be on a ground-fault-protected circuit; local code governs, so ask an electrician. Read more: Aquarium electrical safety basics, Aquarium power and electrical safety
Gravel vacuum · also siphon vacuum, gravel siphon: A siphon tube that pulls waste out of the gravel while draining water. Aqueon says its models are primed by moving the intake tube up and down. Read more: How to prime a gravel vacuum

I

Independent measurement: A figure from a party other than the maker, with its method stated. FishLab and ModestFish each timed air pumps displacing one liter of water, with different setups, so their results cannot be merged. Read more: Air pump noise figures, explained, Air pump flow explained
Inside diameter (ID) · also ID, I.D.: The width of a tube's bore, which must match the fitting it slides over. Danner's check valves fit 3/16 in ID tubing; Tetra's CV4 fits 4 mm ID hose. Read more: 3/16 in vs 4 mm airline tubing

L

Liters per hour (L/h) · also L/h, LPH: A unit of air pump output, 60 times the liters-per-minute figure. Sicce, for example, lists its AIRLIGHT pumps at 60, 90 and 200 L/h. Read more: Air pump flow explained
Liters per minute (L/min) · also L/min, LPM: A unit of air pump output. Tetra lists its Whisper pumps from 0.5 L/min (Whisper 10) to 3.3 L/min (Whisper 100). Multiply by 60 to get liters per hour. Read more: Air pump flow explained
Lithium-ion battery · also Li-ion: A rechargeable battery used in backup pumps and some feeders. Health Canada advises not to use one that is swollen, dented or damaged, and to charge it per the maker's instructions away from soft surfaces. Read more: Battery-backup air pumps
Load rating: The maximum a timer or plug can switch, often listed separately for resistive, tungsten and motor loads. TP-Link rates the Kasa EP25P4 at 15 A but only 1/6 HP for motors. Read more: Timer and smart plug load ratings
Local schedule: A schedule stored in the device so it runs without an internet connection. Whether a given smart plug does this is model-specific; TP-Link does not state it for the Kasa EP25P4. Read more: Mechanical timer or smart plug?

M

Magnetic glass cleaner · also algae magnet: Two magnets, one inside the tank and one outside, that clean the glass without your hand in the water. Sizes are set by glass thickness. Read more: Aquarium maintenance tools
Manufacturer figure · also maker figure: A spec the maker publishes about its own product. Aquarium Co-Op's 43.5 dB and Fluval's "under 28 dB" for the A202 give no test method, so treat them as claims. Read more: Air pump noise figures, explained, Automatic feeder specs compared
Mechanical timer · also dial timer: A plug-in timer driven by a clock dial with pins or trippers. Intermatic's TN311 is a 24-hour model with a 30-minute minimum on/off time and up to 48 events. Read more: Mechanical timer or smart plug?
Motor load · also HP rating: A load with a motor, such as a pump, rated in horsepower because of its start-up surge. The TN311 lists 1/3 HP and the Kasa EP25P4 1/6 HP, far below their 15 A headlines. Read more: Timer and smart plug load ratings

N

NEMA 5-15: The standard North American three-prong grounded plug and outlet. Intermatic lists the TN311 with a NEMA 5-15 grounded plug and receptacle. Read more: Aquarium electrical safety basics
Nitrate · also NO3: The end product of the nitrogen cycle, made from nitrite by bacteria. API's Freshwater Master Test Kit measures it. Read more: Aquarium maintenance checklist
Nitrification: The bacterial conversion of ammonia to nitrite and then nitrate. It uses oxygen: a 2020 tank study found it a smaller oxygen draw than fish metabolism. Read more: Do air bubbles add oxygen to an aquarium?, Free vs total ammonia
Nitrite · also NO2: The middle product of the nitrogen cycle, made from ammonia by bacteria. API's Freshwater Master Test Kit measures it. Read more: Free vs total ammonia
Nitrogen cycle · also cycling: The process in which bacteria turn fish waste ammonia into nitrite and then nitrate. A new tank has to build up these bacteria before it is cycled. Read more: Free vs total ammonia
Non-condensing: A humidity rating meaning the device must not get water condensing on it. TP-Link rates the Kasa EP25P4 for 5-90% humidity, non-condensing, so keep it away from splashes. Read more: Aquarium electrical safety basics
NRTL · also Nationally Recognized Testing Laboratory: Nationally Recognized Testing Laboratory: a lab OSHA recognizes to certify products to safety standards. Intertek states it is one. Read more: UL vs ETL vs CSA marks on aquarium equipment

O

Outside diameter (OD) · also OD, O.D.: The overall width of a tube across its outer wall. Check whether a listing's size is inside or outside diameter before matching fittings. Read more: 3/16 in vs 4 mm airline tubing
Overfeeding protection: A feeder setting that limits extra feeds. EHEIM lists switchable overfeeding protection on its autofeeder+; it is a maker feature, not evidence about fish welfare. Read more: Automatic feeder specs compared

P

pH: A measure of how acidic or alkaline water is. API's Freshwater Master Test Kit measures pH and high range pH. Read more: Free vs total ammonia
Plug adapter · also travel adapter: A fitting that changes plug shape but not voltage. Health Canada says chargers and adapters must match the device's voltage and current; an adapter will not make a 230 V pump safe on 120 V. Read more: 120 V vs 230 V aquarium equipment
Portion slider: A sliding cover that changes the size of a drum feeder's opening. EHEIM uses one on its autofeeder and suggests the two-rotation setting for larger amounts. Read more: Drum vs compartment fish feeders
Power Save mode: Aquarium Co-Op's battery mode that cycles air 15 seconds on and 15 seconds off. It states about 40 hours in Power Save versus 20 hours continuous for current units; maker figures. Read more: Battery-backup air pumps

R

RCD (residual current device) · also residual current breaker: The European equivalent of a GFCI. JUWEL's manual says aquarium devices should run through a residual-current breaker with at most a 30 mA trip current. Read more: Aquarium electrical safety basics
Reliability claim: A statement that a device will work every time. We found no independent repeatability or failure-rate data for any consumer aquarium feeder, so we do not make or repeat such claims. Read more: How to test an automatic fish feeder before a trip, Automatic feeder or fish sitter?
Resistive load: A load such as a heater element that draws steady current. Intermatic rates the TN311 at 15 A resistive. Read more: Timer and smart plug load ratings
Restore state · also power-on behavior: Whether a smart plug or timer goes back on, off or to its schedule after power returns. This is model-specific; TP-Link does not state it for the Kasa EP25P4, so check yours after an outage. Read more: Mechanical timer or smart plug?, Power outage while you're away

S

Ships from / Sold by: The Amazon fields that show who stores and who sells an offer. Tetra links its Amazon brand store, but a store link does not prove who fills a given offer, so check these fields. Read more: Buying aquarium gear online: a checklist
Smart plug: A plug-in switch controlled over Wi-Fi from an app. TP-Link's Kasa EP25P4 uses 2.4 GHz Wi-Fi and is rated 15 A; use it for lights and other noncritical loads. Read more: Mechanical timer or smart plug?
Sponge filter: A filter driven by an air pump: rising bubbles draw water through a sponge, which also moves the surface. Aquarium Co-Op says surface agitation is key to gas exchange. Read more: Do air bubbles add oxygen to an aquarium?
Suggested tank size: The tank range a maker recommends for a pump, such as Tetra's 10 to 100 gallons for the Whisper line or Fluval's up to 80 US gallons for the A202. It is a maker claim, not measured flow at your depth. Read more: Air pump flow explained
Surface agitation: Movement that breaks the water surface. Aquarium Co-Op says air bubbles help mainly by creating water movement and surface agitation, which is key to gas exchange. Read more: Do air bubbles add oxygen to an aquarium?

T

T connector · also tee: A T-shaped fitting that joins two airlines into one or splits one into two. Tetra supplies one to join the two outlets of a dual-port pump. Read more: 3/16 in vs 4 mm airline tubing, Airline tubing and check valves
Total ammonia · also TAN: Free ammonia plus ammonium, the figure most liquid test kits report. Seachem notes 0.02 mg/L free ammonia equals 3.6 mg/L total ammonia at pH 7.0 in freshwater. Read more: Free vs total ammonia

U

UL 1018: UL's standard for electric aquarium equipment used indoors at 300 V or less, such as heaters, pumps, filters and aerators. It is active, in its sixth edition. Read more: UL vs ETL vs CSA marks on aquarium equipment
UL Listed · also UL: A mark showing UL Solutions certified a product to safety standards. UL's Product iQ database lets you look up an exact model or file number; a logo on a listing is not proof. Read more: UL vs ETL vs CSA marks on aquarium equipment, How to verify a UL or ETL listing
UN 38.3 · also UN38.3: The UN Manual of Tests and Criteria section whose design tests lithium batteries must pass for US transport, per PHMSA. It is a shipping rule, not a product-safety certification. Read more: Battery-backup air pumps
USB-C power · also USB-C: A low-voltage USB connector used by some aquarium devices. Aquarium Co-Op's air pumps run from a 5 V USB-C supply, and its auto feeder charges over USB-C. Read more: Battery-backup air pumps

V

Variant: One version of a product, such as a size, voltage or plug. EHEIM's air pumps and Sicce's AIRLIGHT are listed for 50 Hz mains only, so the variant decides whether a pump suits North America. Read more: 120 V vs 230 V aquarium equipment, Buying aquarium gear online: a checklist

W

Water change: Replacing part of the tank water with fresh, dechlorinated water. Merck lists one every two weeks, with the amount depending on stocking level. Read more: Aquarium maintenance checklist, Water changes and testing
Water conditioner · also dechlorinator: A treatment added to tap water to remove chlorine before it goes in the tank. Merck says new water should be dechlorinated, and Python recommends adding conditioner during refill. Read more: Faucet water changers, Aquarium maintenance checklist
Wi-Fi feeder · also smart feeder: A feeder run from a phone app over Wi-Fi. EHEIM's autofeeder+ uses a power supply instead of batteries and sends email alerts when food runs low; its page is for the EU and UK. Read more: Automatic feeder specs compared