App key features

The all-in-one aquarium app.

Planning, stocking, water chemistry, filtration, maintenance and history — one app instead of six tabs, a forum thread and a guess. Every tool in Aquabuildr does one of four jobs.

14 water parameters0–100 health score per tank27 kinds of activity logged21 languages

Build it right

Before you buy a single fish
How the compatibility engine works

It doesn't compare numbers. It knows which fish actually live together.

Every species carries a researched list of the species it can live with. Add a fish and Aquabuildr intersects that list against everything already swimming — so your options shrink, correctly, as the tank fills up.

Vetted tank mates
A researched list per species, intersected across the whole stocking — not a parameter comparison.
Space, not just gallons
Stocking is measured against the volume each species actually needs, including the extra space per additional fish.
Behaviour and group size
Schooling minimums, male-to-female ratios, temperament and territory. A single tetra is a welfare problem, not a stocking choice — the app says so.
Chemistry across the whole tank
Temperature, pH and hardness roll up across every occupant, so you see the window your tank has to hold — not one fish's preference.
Tank Buildr
stock the tank
Tank Capacity29 Gal
8.0 of 29 Gal stocked21.0 Gal left
7IN TANK
72 – 81 °F6.0 – 7.5 pH4 – 15 dKH
Search
AI Suggestion
Info
Tank Capacity
Info
Tank Capacity
The bar warns at 80%, and stops the nonsense at 100%.

Never overstock your tank again. The Size Filter automatically hides fish that need more space than you have left, and the capacity bar changes colour as the tank fills.

Used space84% · getting full
8090100
Tank size alert
Below this species' minimum tank size — with an offer to grow the tank instead of a dead end.
Compatibility warning
Not on the vetted tank-mate list of something already in the tank — with the reason, not just a red cross.
Pair and group alert
Single, pair, trio or group — plus male-to-female ratios, and shrimp and coral notices.
Fit the tank to your room, not the box
Plug in your own dimensions and the calculator works out the volume — and what it can hold. Three shapes: rectangle, L-shaped and D-shaped bow-front, in imperial or metric.
Don't want to build from scratch?
Pre-built Starter Tanks for freshwater and saltwater — stocked, balanced, and carrying their own target temperature, pH and hardness plus a substrate, equipment, food and lighting list. Copy one and modify it.
A database that answers the whole question
Every species carries its own temperature, pH, hardness, minimum tank size, temperament and swim level — and its own vetted list of tank mates.
Beginner guide

Your first tank, in eight steps.

Turn on the step-by-step guide and Aquabuildr walks you from "I want a fish tank" to a cycled, stocked aquarium — where to put it, whether your stand can hold it, what to buy, and the three weeks of patience nobody warns you about. Saltwater gets eleven steps.

  • Translated into 20 languages
  • It won't let you skip ahead
  • Estimates the loaded weight of your tank at 8.34 lb per gallon, before you put it on furniture
  • 23 FAQ entries and a nitrogen-cycle module built in
"Test every few days. Your tank is cycled when ammonia and nitrite both read 0."
The nitrogen cycle, charted
30 days
AmmoniaNitriteNitrate
"Your aquarium is set up and cycling. We'll let you know when it's ready for fish."

Stay ahead of trouble

The years after
Tank Health Score

Your tank, scored out of 100, every day.

Every tank gets a live health score built from the things that actually kill fish: ammonia, nitrite, nitrate, pH, and whether you are keeping up with your own water-change schedule. It drifts down gently when you fall behind and recovers quickly when you catch up.

  • Do This Next gives you one prioritised action, not a list of everything you could do.
  • A 7-day trend, per-parameter ideal ranges, a sparkline on each parameter and a logging streak.
  • New tanks get a grace period — no score and no red state, just four guided prompts until there's enough data.
  • Past 60 days a tank is treated as cycled, and stops being penalised on ammonia and nitrite.
  • The score has a floor of 40. It never bottoms out, because guilt has never saved a fish.
Free: the score, the trend, the parameter cards and "Do This Next". Premium adds Aquabot's read on it, one aggregate score across all your tanks, and the patterns we notice between them.
Reef 40
40 Gal · saltwater · 14 months
Temperature - 78°FPh - 8.1
3112
UpdateReorder
PARAMETERLAST UPDATEDVALUE
Temperature9 Sep 202678 °F
pH9 Sep 20268.1
Salinity8 Sep 20261.025
Alkalinity8 Sep 20268.4 dKH
Nitrate6 Sep 202618 ppm
Calcium2 Sep 2026420 ppm
Ammonia2 Sep 20260 ppm
Four bands, and you always know which one you're in.
Floor of 40 · never zero
Healthy
75 and above
Alert
51 – 74
Alarm
26 – 50
Toxic
Below 26
Water chemistry

Test it, log it, and let the app do the remembering.

Fourteen water parameters, from ammonia and pH through to calcium, magnesium and salinity. Pick the three you want on your dashboard, log the rest as you test them, and watch them graph over time. Set your water-change rhythm once and Aquabuildr tracks how close you are to due.

  • Freshwater tanks see 13 parameters, saltwater 12
  • A Dosing Diary with 20+ preset units
  • Reminders and tasks — once, daily, weekly or custom, filed into Today, Upcoming and Completed
  • Imperial or metric throughout
All fourteen
pHAmmoniaTemperatureNitriteNitrateTDSPhosphateIodineGHKHAlkalinitySalinityCalciumMagnesium
Water change · 25% weeklyDue in 2 days

Know, don't guess

Never guess again
Filter Recommendr

We don't just ask how big your tank is. We ask what lives in it.

Built by aquarists, not marketing.

Every aquarium is different. That's why we analyze your tank's bioload, fish, feeding, maintenance, and setup instead of relying on generic tank-size ratings. The result is a filtration recommendation tailored specifically to your aquarium.

8 questions, one per screen9 aquarium styles1–210 gallonsFree
Community, African Cichlid, Goldfish, Monster fish, Discus, Planted, Reef, Predator or Other — because a heavily stocked 75-gallon community tank is nothing like a heavily stocked 75-gallon cichlid tank, and the engine treats them differently.
Filter Recommendr
your answers scored
Tank Conditions
Tank Size29 Gal
Aquarium TypeFreshwater
Aquarium StylePlanted
StockingModerately stocked
FeedingOnce a day
MaintenanceLow effort
ExperienceBeginner
Budget TierMid-range
Aquabuildr Recommended Filters
Balanced pickQty 1
Fluval 307 Canister Filter
Manufacturer spec303 GPH
Aquabuildr real world212 GPH
Required for this tank145 – 232 GPH
Why we chose this filter
Its real-world 212 GPH lands mid-band for a 29 Gal planted tank — 7× turnover, not the 10× the box implies.
Canister media volume covers a moderately stocked tank at once-a-day feeding.
Flow is adjustable, so the planted layout keeps its surface calm and the CO2 stays in.
Service interval matches the low-effort answer: media rinse every 6 weeks.
Alternative Recommendations
Oase BioMaster 250Qty 1≈8× turnover • 185 GPH real worldView Product
Seachem Tidal 55Qty 1≈9× turnover • 210 GPH real worldView Product
Why this differs from the usual advice
Most charts size a filter off the box rating. We score the flow you actually get with media in, then check it against your stocking and feeding — which is why a 303 GPH unit is the answer here and not a 500 GPH one.
Why is our recommendation different?

Filter manufacturers rate their filters under ideal laboratory conditions. Aquabuildr uses real-world conditions instead. By considering your fish, stocking level, feeding habits, maintenance routine, and aquarium setup, we recommend the filter that will actually keep your water clean — not just circulate it.

Canisters are derated to 65% of their rated flow, hollow-back filters to 75%, sponges to 60%. Above 210 gallons the engine sizes a sump at 25% of tank volume instead.
A filter rated 925 GPH
On the box925 GPH
In your tank≈601 GPH
Three budget tiers, each with a "Why we chose this filter" checklist
"Slightly too much filtration is far safer than slightly too little."
Search
4 questions · Newest
Nitrate stuck at 40 ppm in a planted 29 4h
#nitrate#planted#water-change
Weekly 30% changes, tap water tests at 5 ppm, moderately stocked. Nitrate will not drop below 40. Am I chasing the wrong number, or is the stocking simply too heavy for more
plantedtankpat7 Answers
Honey gourami with a betta — ever a good idea? 11h
#betta#compatibility
Aquabuildr flagged it as a compatibility warning but the local shop swears it works in a 20 long. Who has actually run this pair for more than a month?
nano_nadia12 Answers
Alkalinity drops 0.4 dKH overnight 1d
#reef#alkalinity#dosing
Two-part at 12 ml a day, calcium holding at 420, magnesium fine. Coral growth is good so I assume it is consumption — but should I split the dose?
reefer_marc4 Answers
Is 8 hours of light too much for Monte Carlo? 2d
#planted#lighting
Carpet is pearling but I am getting green spot algae on the glass within four days of a clean.
scapegoat3 Answers
Ask Questions
Discussions

Ask hobbyists, not a search engine.

A proper question-and-answer community built for aquariums. Ask with photos, get answers you can vote on, and mark the one that actually solved it. Link a question to one of your tanks and anyone answering can see what they're dealing with.

Upvotes and downvotes, so the good answer rises
Author Approved marks the reply that solved it
Threaded comments with @mentions, three sort orders, six tank-type categories
Six reputation levels · 22 badges
GuppyTetraCichlidDiscusArowanaLegendary Koi
Free, including answering.
Aquabot
An aquarium expert in your pocket.

Ask anything — why your water went cloudy, whether two species will get along, how long to wait before adding fish. Aquabot answers in plain language, and your conversations are saved so you can come back to them.

Free with limits · unlimited on Premium
My water went cloudy three days after a water change. What did I do?
That's almost always a bacterial bloom — harmless, and it clears on its own. Don't chase it with more water changes; keep feeding light and test ammonia daily until it settles.

See your progress

The record, and the receipts
Fish Trackr

Watch a fish grow up.

Photograph an individual fish over months and keep the whole timeline in one place — growth, health, condition. Post an update in seconds, browse it as a grid or a story, and see the latest shot of every fish right in your inhabitants list.

Size & growthHealthPhysical conditionOther
Photo or short video per update, with a built-in trimmer. Free tracks one fish per tank; Premium unlocks every one of them.
Tetras Community Tank
SearchFilter
Peacock Cichlid
Free tanks track one fish; Premium unlocks every fish in the stock list.
Water change · 25%
Today, 08:12
Nitrate logged · 12 ppm
Yesterday, 19:40
Added 8 × Harlequin Rasbora
3 days ago
Dosed 2 ml trace
4 days ago
CSV Excel
Tank Log & Tank Report

Every change, on the record.

Aquabuildr logs 27 kinds of tank activity automatically — every parameter, dose, fish added, water change and note. Graph any of it, filter it, and take it with you as CSV or Excel whenever you want.

Free keeps three months of history. Premium keeps it for life and unlocks export.
Feed
See what everyone else is keeping.

Share a tank, follow the hobbyists whose work you like, and browse Explore for builds you'd never have thought of. Tap through to see exactly what's in a tank you admire — the stocking, the equipment, the parameters they hold.

Follow and followers, likes and threaded comments with @mentions
One search across fish, species and people
Private by default — set each tank to Private, Friends or Public
Products

Discover recommended products for your setup.

Curated gear matched to your actual tank — its size and dimensions, its water type, and the specific fish, substrate and equipment already in it. No generic bestseller list.

Matched on tank size range and physical dimensions
Water type, plus the fish, substrate and equipment on the tank
An experience-difficulty and tier rating on every product

Product links go to Amazon. Aquabuildr may earn a commission on qualifying purchases — this does not affect what we recommend. [Disclosure wording pending legal sign-off.]

Free and Premium
Free lets you record. Premium helps you protect.
Compare the plans
Tanks
1 free · unlimited on Premium
History
3 months free · lifetime on Premium
Fish Trackr
1 fish per tank · every fish on Premium
Export
CSV and Excel, on Premium
Tank Buildr, Filter Recommendr, the Health Score, water logging, Discussions and the Feed are free for everyone. Premium is $4.99 a month or $39.99 a year.
We warn you at the point of stocking, not in a policy page.

"Always purchase coral from accredited, sustainable dealers. Choose aquacultured or farmed specimens to protect wild reefs and avoid harming natural ecosystems. Never buy corals collected from the ocean."

See the Accredited Vendor programme