About Closed Loop
Search "self-sustaining aquarium" and you get two things: a sealed jar of brine shrimp sold as a desk toy, and a forum thread from 2011 where the one right answer is buried under forty wrong ones. Closed Loop is the resource that should exist instead.
What we are
Closed Loop is the independent reference for self-sustaining, human-built living ecosystems: bioactive vivariums and terrariums, low-tech Walstad planted aquariums, and balanced living ponds. Systems that run on plants, biology, and a cleanup crew instead of a wall of equipment. A person builds them on purpose, and they hold for years.
A closed loop is a system whose waste feeds its own inputs: animal waste becomes plant food becomes clean water, and dead leaves become soil. That is the name and the thesis. Get the biology right and the filtration is free.
What makes it different
Two things. First, a real compatibility database: 117 records of plants, livestock, cleanup-crew invertebrates, and gear, with the temperature, pH, hardness, light, and size that decide what can share a system. Every guide renders from it, so a number on a page traces to a record, not to someone's memory. Second, a build planner that computes on that database and tells you, before you spend a dollar, whether your plan will balance.
We are independent. We link to gear and plants with disclosed affiliate links, and we say plainly when the cheaper option is the right one. We are not a store, and we do not have a brand of substrate to sell you.
What we do not do
We teach ecosystem design and husbandry: plants, water chemistry, hardscape, cycling, and species compatibility. We do not diagnose or treat sick animals. If an animal is ill or injured, that is a veterinarian's job, and we will tell you so on every page that touches livestock. Knowing where our expertise ends is exactly why you can trust it where it does not.
And we are honest about the work. "Self-sustaining" means the biology does the filtration, not that you never touch it. You still top off, feed, prune, and watch. The jar that never gets touched is dead by month three, and we will not sell you that.
The one test for everything we publish
Read it aloud. If an experienced keeper, someone who has cycled a dozen tanks and crashed a couple, would say it to another keeper and be believed, it ships. If it sounds like it was written to rank on a search engine, it does not.
One build breakdown a week.
A stocked, balanced setup pulled apart: the plants, the cleanup crew, the parameters, and where it would go wrong. Free.
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