Why these three parameters get their own conversation

Reef tanks have a long list of parameters that matter. Alkalinity, calcium, and magnesium get their own conversation because they drive coral skeletal growth, they are consumed continuously by a live reef, and they have to be replaced with consistent dosing. The other parameters describe the tank. These three describe what the tank is using up.

Track them well and the tank is mostly running itself. Track them poorly and everything else feels harder than it should.

Testing cadence that actually works

A simple rule for an established reef: test all three on the same day each week. The same day matters more than the day you pick. If life gets in the way some weeks, do the next test on the regular day rather than catching up out of phase.

For a new tank, or for any tank you have just changed dosing on, test more frequently for two or three weeks while you watch the response. Once values look stable, back off to the weekly rhythm.

What to log every time

A reef tank app earns its keep when you log a few simple things alongside the number:

  • The value (dKH, ppm, ppm).
  • The test source (Hanna checker, Salifert kit, ICP, etc.).
  • A note for any unusual context: travel week, dosing change, new coral.
  • The date and time, even if the app does this for you.

Consistency in the source matters as much as accuracy. A Salifert kit reading 8.0 dKH and a Hanna checker reading 8.3 dKH are not the same data point. If you track which source produced which number, the history is comparable. If you do not, the chart is fiction.

The three pillars, in plain language

A short field guide for what to actually aim for, with the caveat that mature tanks find their own steady values and the goal is stability around your number, not chasing a textbook ideal.

  • Alkalinity. Most reefs sit between 7.5 and 9.0 dKH. Stability matters more than the exact target. Drift of more than 0.5 dKH in a week is meaningful.
  • Calcium. Most reefs sit between 400 and 450 ppm. Calcium moves slowly and is usually the easiest of the three to keep stable.
  • Magnesium. Most reefs sit between 1250 and 1400 ppm. Magnesium does not move much on its own but it has to be there for the calcium and alkalinity system to work.

Reading the relationship between alk, dosing, and growth

Alkalinity is the most informative of the three because it changes fastest in response to coral growth and dosing. A growing reef will pull alkalinity down. A dosing pump that lifts alkalinity above your set point and lets it drift back is not as stable as one that simply holds the value.

A reef tank app helps here when the alkalinity trend and the dosing log live in the same place. You can see at a glance whether your daily dose is keeping pace, falling behind, or overshooting. Without that side-by-side view, dosing tuning becomes guesswork.

How Reef Trak handles the three pillars

Reef Trak treats alkalinity, calcium, and magnesium as first-class parameters with their own detail views, custom ranges, and multi-week charts. Each test you log records the value, the source, and any note you want to attach. The same tank also holds your dosing log so you can correlate consumption with the products you are running. Reports and AI exports include the full history of all three so a longer-term picture is always available.

It is the boring kind of tooling that pays off in year three of a reef, when you can answer "what was my alkalinity doing during the last bleaching event" instead of guessing.