Most broken Aquarium grids come from one of six mistakes, and the biggest is filling a tank before it’s certain. The others are about how water behaves: it spreads across a tank, it runs down, each tank keeps its own level, and dry spreads up. Each one is below, with how to spot it.
If you’re new, the rules and how to solve pages explain the ideas these mistakes go wrong on.
1. Filling a tank before it’s certain
When a tank could be filled to one level or another, it’s tempting to pick one and see. Usually nothing tells you straight away. We took every one of the game’s levels, put water (and everything it flows into) in one square that should be dry, choosing one that broke no number yet, and kept making honest moves until a row or column number turned red:
| Track | Red number appeared | Moves before it (median) | Longest |
|---|---|---|---|
| Easy 6×6 | 49 of 50 | 5 | 15 |
| Medium 8×8 | 49 of 50 | 13 | 25 |
| Hard 10×10 | 43 of 50 | 24 | 47 |
On the rest, no number ever turned red: the honest moves ran out first, with the grid still wrong. Here’s one on Medium level 15, with wrong water in row 7, column 7:
Fourteen honest moves later, column 8 has too little room left for its number. The wrong water isn’t in column 8 at all.
How to avoid it: only fill or dry a square when a technique makes it certain. If it could still go either way, leave it and count somewhere else.
2. Filling one square of a tank’s row
Water spreads level across a whole tank. If a tank has three squares on a row, they’re all water or all dry; one on its own isn’t possible.
How to avoid it: whenever you put water in a square, fill the rest of its tank on that row straight away. In the game, a tap does it for you.
3. Forgetting that water runs down
Water in a square means water in every row of its tank below, too. Forget that, and a column looks as if it has room when it doesn’t.
How to avoid it: count a tall tank as everything it would bring with it. That’s too much water, and on Hard levels more than half the moves that use it are about columns, where the water runs down.
4. Thinking side-by-side tanks share a level
Each tank is filled on its own. Two tanks next to each other can be at completely different heights, even if the wall between them is short.
How to avoid it: follow the thick walls. Water only spreads within its own tank.
5. Forgetting that dry spreads up
A dry square means every row of its tank above it is dry too. Miss that, and you’ll count squares as open that can’t hold water.
How to avoid it: when you mark a square dry, mark everything above it in the tank. In the game, the second tap does it for you.
6. Not marking dry squares at all
It’s easy to mark only the water, but about half of every solution is dry: 50% of the squares on the game’s Medium and Hard levels. Without dry marks, you can’t see when a line has just enough room left, or when keeping a square dry would leave no room.
How to avoid it: mark a square dry as soon as it’s certain, just as you would water.
How to recover from a mistake
- A red number means a line has too much water or too little room, but the mistake may be elsewhere, sometimes a long way back. Undo to the last move you were sure of.
- Press Stuck? It rings a wrong square before anything else, so you know exactly where.
- Stuck with no red number? Count every row and column again, then look at when you get stuck.