A small betta tank loses water quietly all summer, and a top-up record is how you prove to yourself what actually happened: how much water left, how often you replaced it, and whether the tank's rhythm is changing. Each top-up deserves its own short entry with the same four parts every time, written when you pour rather than reconstructed at the end of the week. Kept that way, the entries trace the tank's evaporation pattern through the hottest stretch of the year and give anyone covering for you an exact picture of what the tank needs.
The Four Parts of Every Entry
Start with the entry-label date, written as the day itself, such as Saturday, so entries stay in order without any guesswork. Next, record the amount replaced in a measure you can repeat, such as cups or a marked jug filled to the same line each time; roughly right is acceptable, consistently measured is better. Third, note the water added: that it was conditioned water, prepared the way you always prepare replacement water for the tank before it went in, so a later reader knows raw tap water never went straight into a small tank. Fourth, record the tank's level mark, meaning where the water sat against your reference line before the top-up and where it sat after. That pair of marks turns a vague sense that the level dropped into a measured drop you can compare across weeks.
Mark the Level and Use It Every Time
The level mark is the habit that makes the rest of the record honest. Choose one fixed reference on the tank, such as a small line on the glass at the full level or the bottom edge of the rim, and judge every check against it. Note how far below the mark the water sat when you found it, in finger widths or fractions of an inch, then top up back to the mark and write the amount that took. A consistent mark also protects the heater and filter intake, which need the water above a minimum level to run safely, so the record quietly guards the equipment as well as the fish.
The Summer Rhythm
Heat speeds evaporation, so summer entries tell a faster story than winter ones. Warm room air, longer light hours, and any increase in surface movement all pull water out more quickly, and an uncovered tank loses more than a covered one. Expect the gap between top-ups to shrink during a heat wave and widen again when nights cool, and let the record show that rhythm instead of treating each drop as a surprise. Reading a month of entries, you can see whether the tank needed attention every two days or every four, which is exactly the information a friend needs if you travel during the hottest weeks. If the level suddenly falls much faster than the recorded rhythm, with no heat change to explain it, check for a slow leak at the seams and around equipment before assuming evaporation alone is responsible.
Top-Ups Are Not Water Changes
Keep the top-up record separate from water changes in your notes, because the two jobs do different work. A top-up replaces only the water that evaporated, and since evaporation leaves dissolved waste behind, topping up never dilutes what has built up in the tank. Your entries should therefore never be used to argue that a water change can be skipped; if anything, a summer of faithful top-up entries highlights how much water left while everything dissolved in it stayed. Note water changes on their own lines, with their own amounts, so the two rhythms sit side by side and neither masquerades as the other. Together they give a complete picture of the tank's summer: what evaporated, what you replaced, and what you deliberately renewed.
Held in one place by KinsLe, Pet Passport lines up a summer of dated top-up entries so the betta tank's evaporation rhythm reads at a glance.