Guides
Long-form notes on the chemistry, observation, and small daily rituals of the hobby. One per month. Mascot-led.
Ammonia in a cycled tank: which side of the balance moved
A cycled tank showing ammonia means production briefly outran your filter — not a collapsed cycle. The seven usual causes, ranked, and the fix.
How often to change aquarium water, and why your nitrate already knows the answer
25–50% weekly is the honest default, but the right cadence comes from your nitrate trend, not a sticker. The maths, the exceptions, and a starting table.
The nitrate-to-phosphate ratio, and why your tank barely reads it
Chasing a magic NO3:PO4 number rarely fixes algae. Here's where the 10:1 rule of thumb comes from and why absolute levels and stability matter more.
The water test log, and why your memory is the least reliable instrument you own
Drift is invisible day to day and obvious in a log. What to record, how often to test each parameter, and a free CSV template to start with.
Why your KH keeps sliding, and what actually holds it up
KH falls because your tank burns carbonate faster than water changes replace it. The mechanism, the pH-crash danger, and how to hold the line.
A week-by-week calendar for your first freshwater month
A week-by-week look at what happens in the water from setup day to first stable readings, and how to dodge the standard new-tank mistakes that kill fish.
GH vs KH, and why your fish care about one and your pH about the other
General hardness and carbonate hardness are two independent numbers. One builds shells, the other holds pH steady. Here is the chemistry and the targets.
How the forecast finds your cycle, and why it draws a sine
How reefnotes reads the high-low envelope of a water-change cycle, why the forecast draws a smooth sine instead of a sawtooth, and where it misleads.
The nitrogen cycle in plain language
How fish waste turns into plant fertiliser, why nitrite is the real danger during cycling, and what it actually means to call a tank cycled.
Running a planted tank without CO₂
Species, light, and lean dosing for a low-tech planted tank with no CO₂ injection — and why patience does more work here than any piece of gear.
A walk through the reefnotes trend chart
A guided tour of the aquarium-detail trend chart: the historical line, the gap break, the cycle forecast, the WC markers, and what the staleness gate does.
Shrimp-safe parameters, and the numbers that quietly kill
The water-chemistry window where neocaridina and caridina shrimp actually thrive, plus the parameters that wipe out a colony before you see distress.
When a bigger water change helps, and when it just stresses the tank
The dilution maths behind water-change size and cadence, what a swap does to nitrate versus KH and GH, and when a bigger change is the wrong fix.
Reading CO₂ from pH and KH, no meter required
How to estimate dissolved CO₂ in a planted tank from two numbers you already measure, the chemistry behind it, and when the result lies to you.
These guides give you the model. reefnotes applies it — to your tanks, your tests, your cadence — in the background.