Guides
Everything, in order.
108 guides on building living ecosystems that run on biology, not equipment. Every one renders real parameters from the database and links into the build planner. No filler, no dead jars.
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Self-Sustaining Planted Aquariums
Capping Soil With Sand: How Deep, and Why
Cap depth is the difference between a tank that clears in a week and one that leaks mud for a month. One inch of sand over the soil is the number, and here is why.
Dirted Tank vs Aquasoil: Which Substrate Is Right for You
A dirted 10-gallon costs about the price of a bag of topsoil, and an aquasoil tank of the same size costs several times that. Both grow plants; they solve different problems.
Floating Plants for Low-Tech Tanks: The Best Nutrient Sponges
A mat of floating plants is the cheapest nitrate export a low-tech tank can add. They feed on air, grow fast, and shade the algae that surplus nutrients would otherwise feed.
How to Build a Self-Sustaining Shrimp Tank
A shrimp colony is the closest thing to a tank that feeds itself, because the shrimp eat what the tank produces. The catch is the water: get the minerals wrong and the colony cannot molt.
How to Set Up a Low-Tech Planted Tank
A low-tech planted tank skips the CO2 and the pressurized gear and still grows a full scape, just slower. Here is the build, the plant list, and what to stock.
How to Set Up a Walstad Tank: Soil, Sand, and No Filter
A dirted tank clouds for about a week, then clears on its own once the bacteria catch up. The soil under the sand does the filter's job for free. Here is how to build one.
The Best Low-Light Aquarium Plants for a No-CO2 Tank
Low light is not a limit on what you can grow, only on which plants. These are the ones that never wanted strong light or CO2 in the first place.
The Best Plants for a Walstad Tank (and Why They Work)
The best plants for a Walstad tank are the ones that grow fast and eat ammonia hard in the first month. Here are the ones that hold under low light, and why.
The Best Soil for a Planted Aquarium (Dirted Tank Substrate)
The best soil for a dirted tank is the cheapest plain organic topsoil with nothing added. The fertilized, premium bags are the ones that spike ammonia. Here is how to choose.
The Cheapest Way to Start a Planted Tank
The cheapest planted tank is not the one with the cheapest gear. It is the dirted 10-gallon that needs almost no gear: topsoil, sand, a shop light, and fast plants.
The Common Walstad Tank Mistakes (and How to Avoid Them)
A Walstad tank almost never fails because the method is wrong. It fails from five or six specific, avoidable mistakes: thin planting, the wrong soil, and stocking too early.
The El Natural Aquarium: Diana Walstad's Original Idea
El Natural is the hobby's name for Diana Walstad's low-tech, soil-based tank. The plants and the dirt do the filter's job, and the balance comes from biology, not gear.
The No-Filter Aquarium: What It Takes to Run One
A no-filter tank is not a tank with the filter removed. It is a tank where the plants and substrate do the filter's biological work, which only holds if you build for it.
The Walstad Jar: A No-Filter Ecosystem on a Desk
A wide-mouth jar of soil, plants, and shrimp runs with no filter and no heater on a desk. It is the smallest honest Walstad build, and the least forgiving.
The Walstad Method, Explained: How a Tank Runs on Dirt
A Walstad tank has no filter and no CO2, yet it runs clear for years on a bag of soil. The soil feeds the plants and the plants do the filtering. Here is why that works.
Walstad Tank Lighting: How Much, and For How Long
Give a dirted tank 6 to 8 hours of light a day, not the 10 or 12 a high-tech scape runs. In a low-tech tank, extra light feeds algae, not plants.
Bioactive Vivariums & Terrariums
A Bioactive Substrate Recipe You Can Mix Yourself
A good bioactive substrate is four cheap ingredients in the right ratio: a coir base, bark and charcoal for structure, sphagnum for water. Here is the mix.
ABG Mix Explained: The Standard Bioactive Substrate
ABG mix is not soil. It is a chunky blend of tree fern, sphagnum, charcoal, and bark that drains fast, holds moisture, and does not pack down for years.
Crested Gecko Bioactive Setup: Enclosure, Plants, Cleanup Crew
A crested gecko runs at room temperature with no heat lamp, which makes it one of the few reptiles suited to a planted, bioactive enclosure. Here is the build.
Dart Frog Vivarium Setup: A Complete Bioactive Build
A dart frog vivarium runs in a narrow band: 72 to 80 F and humidity above 80 percent, never over 82 F. Here is the complete bioactive build.
How to Make a Terrarium That Lasts
Most terrariums die within a month, and it is rarely the plants. It is a jar with no drainage that rots from the base, or a sunny shelf that cooks it.
How to Set Up a Bioactive Vivarium, Layer by Layer
A bioactive vivarium's cleanup crew of springtails and isopods eats the animal waste around the clock, so you rarely scoop it out. Here is the layer-by-layer build.
How to Set Up a Paludarium (Land Meets Water)
A paludarium is half aquarium, half vivarium in one tank: land above, shallow water below. Here is how to build one for a group of vampire crabs.
Isopods for Bioactive Setups: Which Species, and Why
Not all isopods suit every viv. Dwarf whites stay small and safe for dart frogs; dairy cows clear heavy waste but need feeding. Here is how to match them.
Leaf Litter in a Vivarium: Cleanup-Crew Fuel
Leaf litter is not decoration. It is the food that keeps springtails and isopods alive between feedings and the cover isopods breed under. Here is how to use it.
Mourning Gecko Vivarium: A Nano Bioactive Colony
The mourning gecko is the only common gecko you keep in a group, because it is all-female and breeds without a mate. A 12 by 12 by 18 in planted viv holds a colony.
Springtails in a Vivarium: The Mold-Eating Foundation
Add springtails two to four weeks before the frog, not after. They are the crew that eats the mold blooming on new wood, and one culture seeds an 18-inch vivarium.
Terrarium vs Vivarium: What's the Difference?
A terrarium is a planted glass box. A vivarium is a planted box built around a live animal and held to that animal's parameters. The difference runs deeper than the name.
The Best Cleanup Crew for a Vivarium
A vivarium cleanup crew is a few dollars of springtails and isopods that replace a weekly cleaning. Seed it two to four weeks before your animal goes in.
The Best Plants for a Bioactive Vivarium
Half the plants sold for terrariums rot in a real vivarium's 60 to 100 percent humidity. Here are the ones that hold up, and the light each one needs.
The Closed Terrarium: A Sealed Ecosystem That Waters Itself
A sealed terrarium waters itself: the moisture it starts with evaporates, fogs the glass, and rains back down, the same few ounces cycling for years.
The Moss Terrarium: Cool, Low-Light, and Nearly Hands-Off
A sealed moss terrarium recycles its own water for months and asks for a few minutes a season. The trade is that it wants cool, bright shade, not a warm sunny sill.
The Vivarium Drainage Layer: Why It Matters and How to Build It
The drainage layer is the cheapest 2 inches in a vivarium and the one beginners skip, then wonder why the soil smells like a pond a month later.
What Is a Bioactive Vivarium? The Living Cleanup Crew Explained
A bioactive vivarium has no spot-cleaning routine. A colony of springtails and isopods eats the waste, the mold, and the dead leaves in the soil before you ever reach for a tool.
Living Ponds
A Balanced Pond With No Pump: Can It Work?
A pond without a pump can hold clear, oxygenated water, as long as the plants and the fish load are matched. It works in a cool, well-planted pond and struggles in a hot, overstocked one.
A Stock Tank Pond: The Easiest Patio Water Garden
A galvanized stock tank makes a pond with no digging: one vessel, a few plants, a small school of cool-water fish. In a 100-gallon tank the balance is the same as a big pond.
Building a Small Pond Ecosystem That Runs Itself
A 50-gallon stock tank can hold clear water, a lily, and a school of minnows for years on plants and snails alone. Here is how to build the closed loop.
Goldfish Pond Setup: Sizing It So It Balances
A common goldfish reaches 8 inches and pushes a heavy bioload, which is why the pet-store bowl is the wrong container by a factor of ten. Size the pond first.
How Much of a Pond Should Be Covered in Plants?
Cover 40 to 60 percent of a pond's surface with plants and the water clears itself. Less than that feeds algae, and more than that starves the open water of gas exchange.
How to Build a Self-Sustaining Pond
A pond with plants shading half its surface and only a few fish will filter and clear itself. The pump is for a waterfall, not for keeping the water alive.
How to Build a Wildlife Pond
A wildlife pond does the opposite of a fish pond: leave the fish out, and frogs, dragonflies, and newts move in within a season. Here is how to build one.
How to Clear Green Pond Water Naturally
Green pond water is not dirt, it is a bloom of single-celled algae feeding on excess nutrients and sunlight. Starve it of both and it clears without a single chemical.
How to Make a Container Pond on a Patio
A half-barrel or a stock tank on a patio, planted to shade half the surface and stocked with a few minnows, balances without a pump. The small volume is the catch.
How to Overwinter a Pond and Its Fish
A pond and its fish overwinter in place if one section is 2 ft deep and a hole stays open in the ice. The cold is not the threat. A sealed, iced-over surface is.
How to Stop Mosquitoes in a Pond, the Living Way
Mosquitoes need still water and about 10 days to breed. A pond with fish and a moving surface never gives them either. Here is how to design them out.
Stocking a Pond With Fish Without Wrecking the Balance
The mistake that breaks a pond is not the wrong fish, it is too many of the right one. Here is how to stock a pond so the biology keeps up.
The Best Oxygenating Pond Plants
A submerged plant releases most of its oxygen straight into the water. The three that do it best also starve the algae that turns a pond green.
The Best Pond Plants for a Clear, Balanced Pond
The best pond plant is the one that shades the water. A clear pond is a light-and-nutrient problem, and plants over 40 to 60 percent of the surface solve most of it.
Plant & Species Compatibility
Aquarium Fish and Plant Compatibility: What Goes With What
The mistake is rarely two fish that fight. It is a fish and a plant that want different water, or a goldfish put in with plants it will strip.
Aquarium Snails for Planted Tanks: The Useful Ones
A nerite snail grazes algae for a year and never leaves a hatching egg; a bladder snail can turn one into fifty in a month. The gap between a useful snail and a plague is mostly your leftover food.
Betta Tank Mates: What Actually Works
Most betta community-tank ideas online pair a fish that runs at 78 to 82 F with tankmates that either nip its fins or need water it does not. The list that actually works is short, and half of it is snails.
Cherry Shrimp Tank Mates: Who's Safe With a Colony
A cherry shrimp is 1.2 inches long and bite-sized to almost any fish, so the safe-tankmate list is short and mostly about mouth size. The other catch is temperature: shrimp want it cooler than most nano fish do.
Cold-Water Aquarium Fish for an Unheated Tank
The white cloud minnow does poorly in warm tropical water and does best at 60 to 72 F, which makes an unheated tank its ideal home, not a compromise.
Crested Gecko vs Dart Frog: Which Vivarium Is for You
A crested gecko wants a room-temperature tank you can open and handle; a green-and-black dart frog wants a sealed vivarium at 80 to 100 percent humidity that you only watch. Both are called beginner bioactive, and they are nearly opposite animals.
Dart Frog Safe Plants for a Bioactive Vivarium
The worry with dart frog plants is usually toxicity. It is the wrong worry: a dart frog eats springtails, not leaves. The real bars are humidity and pesticide-free.
Do Goldfish Eat Plants? What Survives a Goldfish Tank
Goldfish eat soft plants and uproot the rest, so a goldfish tank is not a place for a tender carpet. A short list of tough plants survives them, and here is why each one does.
Peaceful Community Fish That Get Along
A neon tetra and a guppy are both sold as peaceful, and keeping them in one tank still kills one of them slowly. Peaceful is only half the question; the other half is whether they want the same water.
Plants Goldfish Won't Eat (or Uproot)
A goldfish will strip a planted tank to bare stems in a weekend. Three plants survive it, for the same two reasons: leaves too tough to eat and roots too anchored to pull up.
Shrimp-Safe Plants (and the Cover a Colony Needs)
A cherry shrimp will not eat a healthy plant, so shrimp-safe is not about the plant. It is about which plants grow a colony and which arrive carrying the copper or pesticide that wipes one out.
Stocking a 10-Gallon Tank: Ideas That Actually Fit
A 10-gallon fits one small school or one centerpiece fish, plus a cleanup crew, not the dozen species beginners try to pack in. Here are four plans that actually work.
The Best Algae Eaters for a Planted Tank
No algae eater fixes a tank that makes too much algae. The best ones graze the last of it once your light and nutrients are already close, and each one clears a different algae.
The Best Bottom-Dweller Fish for a Planted Tank
A corydoras is not a tank vacuum. A bottom-dweller forages the leftover food a mid-water school misses, and the wrong one grinds its barbels off on sharp gravel within a month.
The Best Centerpiece Fish for a Nano Tank
A nano tank holds one centerpiece, not a community. The three fish that carry a 5 to 10 gallon on their own, and the school you pick when you want movement instead.
The Best Fish for a Planted Tank
A goldfish strips a planted tank to bare stems in a week. The best planted-tank fish do the opposite: they leave the plants alone and suit the soft, warm water most aquarium plants want.
The Best Hard-Water Aquarium Fish
Hard tap water, GH above 12 and pH near 8, is not a problem to fix. It is a stocking list you have not read yet: livebearers and a few others want exactly what comes out of a limestone-region tap.
The Best Nano Fish for Small Tanks
Nano fish is a real category with a hard ceiling: under about 1.5 inches adult, in a 5 to 10 gallon tank. Most fish sold as nano, like the neon tetra, actually want 10-plus gallons and get too restless for a 5.
The Best Soft-Water Aquarium Fish
A neon tetra in hard, alkaline tap does not die on day one. It fades over a month. Soft water fish want the opposite: low hardness and a pH under 7.0.
What Fish Can Live With Shrimp?
The honest answer: adult cherry shrimp survive with small, peaceful fish, but shrimplets get eaten. The real question is which fish let the colony grow anyway.
Water Chemistry & the Nitrogen Cycle
Ammonia in a Fish Tank: Where It Comes From and How to Drop It
Ammonia is the first poison every tank produces, and 0.25 ppm is enough to burn a fish's gills. In a cycled tank you never see it. When a test shows it, the tank cannot keep up.
Aquarium Tannins and Blackwater: What They Do
Tea-colored aquarium water is not dirty water. Tannins leach from driftwood and leaves, tint the tank amber, lower pH a few tenths, and suit the soft-water fish that evolved in them.
Beneficial Bacteria: The Invisible Filter
The filter is a box of surfaces. The bacteria growing on those surfaces are the part that actually processes waste, and they take about a month to build.
Fishless Cycling: The Humane Way to Start a Tank
Fish-in cycling asks an animal to live in rising ammonia for a month. A fishless cycle reaches the same finished tank with a bottle of ammonia and nothing alive to poison.
GH and KH Explained: The Hardness Numbers That Matter
Two tanks at the same pH of 7.0 can be right for completely different animals, because pH hides the two numbers that decide it. GH and KH are those numbers.
How to Cycle a Fish Tank (Before Any Fish Go In)
A new tank of clear water is one of the most dangerous places you can put a fish. Cycling builds the bacteria first, so the water is ready before anything lives in it.
The Aquarium Nitrogen Cycle, Explained Simply
Fish waste becomes ammonia, ammonia becomes nitrite, nitrite becomes nitrate. Two colonies of bacteria run the whole conversion, and it takes about a month to build.
What Is pH in an Aquarium, and Does It Matter?
Most fish care less about the exact pH number than whether it holds still. A stable 7.8 beats a 7.0 that drifts half a point a day.
Getting Started & Build Guides
Aquascaping for Beginners: Your First Layout
The fastest way to spot a beginner scape is symmetry: a stone dead center, matched pairs, everything even. Real underwater ground is never symmetrical.
How to Grow a Planted Tank Without CO2
Almost every plant that fails in a low-tech tank fails for one reason: too much light and no carbon to use it. The fix is to cap the light, not raise it.
How to Make a Jar Aquarium (a Real One)
A fish in a jar is the picture most people have, and it is the one build a jar cannot do. A real jar aquarium is a planted shrimp jar: no filter, no heater, invertebrates only.
How to Plant Aquarium Plants So They Actually Root
Half of a new tank's plant losses happen at the planting: a buried rhizome, a floated stem, a melting crypt pulled out too soon. Here is the method.
How to Set Up a 10-Gallon Planted Tank
A 10-gallon holds enough water to stay stable and little enough to sit on a shelf, which is why it is the size most keepers should start with. Here is the whole build and what actually fits in it.
How to Set Up a 5-Gallon Planted Tank
A 5-gallon is the smallest tank worth starting on, and it holds exactly one of three things well: a betta, a shrimp colony, or a true nano school. Here is the build and the three paths.
How to Set Up a Betta Tank the Right Way
A betta needs 78 to 82 F, a lid, and water that barely moves. The store cup is none of those. Here is the tank that actually suits one.
How to Set Up a Desktop Ecosystem
A 2-gallon jar of moss and shrimp on a desk runs with no filter and no heater, but only if you stock inverts and leave fish out. Here is the build.
How to Set Up a Nano Tank (Under 10 Gallons)
A nano tank is any aquarium under 10 gallons, and the small water volume makes it swing faster and demand more attention, not less. Here is how to set one up and stock it honestly.
How to Set Up a Planted Aquarium, Step by Step
A planted aquarium is built in one order that does not bend: substrate, light, plants, water, weeks of waiting, then fish. Skip to the fish and you fight ammonia for a month.
How to Set Up a Shrimp Tank
A cherry shrimp colony grazes biofilm you cannot see and breeds on its own, given the right minerals and no copper. Here is the build, in order.
How to Set Up a Terrarium for Beginners
A closed terrarium waters itself: the same cup of water evaporates, fogs the glass, and rains back down for months. The layers underneath do the real work.
How to Set Up an Aquarium in a Bowl (Without Killing Anything)
A goldfish in a bowl is the oldest way to kill a fish slowly. A bowl can hold a stable living system, but only if you stock invertebrates and plant it hard.
The First Planted Tank Shopping List
A planted tank needs about ten things, and the animals are not among them yet. Here is the shopping list, in the order you actually buy it.
Troubleshooting
Algae on Aquarium Glass: Why It Keeps Coming Back
You wipe the front glass on Sunday and it hazes green by Wednesday. That is a light and nutrient signal, not a dirty tank. Here is what the film is telling you.
Brown Algae (Diatoms) in a New Tank: Why It Shows Up
Brown algae in a new tank is a diatom bloom, not a disease. It coats the glass and sand in a rust-brown film for a few weeks, then usually fades as the tank matures.
Green Aquarium Water: What Causes It and How to Clear It
Green aquarium water goes from clear to pea-soup in 2 to 3 days because it is billions of free-floating algae cells. A snail or a water change cannot touch it.
Green Spot Algae on Glass and Plants
Green spot algae is the one film a cloth will not wipe away: hard green discs on the glass and the oldest leaves. It tracks strong light more than dirty water.
High Ammonia: What to Do Right Now
Any ammonia reading above 0 ppm is an emergency. Here is what to do in the next hour, what not to touch, and why the tank spiked in the first place.
How to Get Rid of Aquarium Algae (by Type)
Every tank grows algae. The type tells you the cause: green film is a light problem, stringy algae a nutrient problem. Here is how to read it and fix it.
How to Get Rid of Black Beard Algae
Black beard algae grows in dark tufts on slow plants and equipment, and it means your CO2 is low or unstable. Scrubbing does not fix it; steadying the tank does.
Mold in a New Vivarium: Normal, and How to Handle It
White fuzz on the wood of a three-week-old vivarium is almost always a harmless mold bloom, not a failed build. Here is why it shows up and how the crew clears it.
Why Are My Aquarium Plants Melting?
You plant a new crypt and a week later it is transparent mush. Usually the roots are fine: the plant is shedding farm-grown leaves and rebuilding for your water.
Why Are My Shrimp Dying? Water, Molting, and Copper
Cherry shrimp usually die for three ordinary reasons: the water swung, it is too soft to molt in, or something added copper. All three are preventable.
Why Is My Aquarium Water Cloudy? The Three Causes
A new tank that clouds on day four is usually cycling, not failing. The color tells the cause: white is bacteria, grey is dust, green is algae.
The Database & Planner
Aquarium Bioload, Explained
A full-grown goldfish makes more waste than a dozen shrimp. That gap is what bioload measures: the load on your water, not the inches in your tank.
Are These Fish Compatible? How to Check in a Minute
Two fish get along when their numbers overlap: temperature, pH, hardness, and adult size, before you ever reach temperament. Checking takes about a minute.
Fish pH Requirements: Reading the Ranges Right
A neon tetra wants pH 5.5 to 7.0 and a guppy wants 7.0 to 8.0, and no single tank pH is right for both. Reading the range, not chasing a number, is the whole skill.
How Many Fish Can Go in a Tank? A Better Rule
One inch of fish per gallon says a goldfish fits a 10-gallon. The rule ignores adult size and bioload, and it is how tanks get overstocked.
How the Build Planner Works, and What It Checks
Most first tanks fail on a mismatch you cannot see: a fish that wants 78 to 82 F sharing water with one that tops out at 72 F. The planner catches that in five questions.
The Aquarium Cleanup Crew: Who Does What
An amano shrimp eats hair algae a nerite ignores; a nerite scrapes glass an amano leaves. A cleanup crew is not one animal, it is a set of specialists.
Understanding Aquarium Plant Light Requirements
The plant is rarely the problem. The light reaching the substrate is: dwarf hair grass needs 40 or more PAR to carpet, and stretches thin under a weak clip light.
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