Tank Checker (Interactive)
Mistake #1 — Overcrowding
Relying on “gallons per turtle” hides two realities: bio‑load and behavior. Turtles add particulate waste and dissolved metabolites that stress filtration and consume oxygen. At the same time, individuals defend basking spots and swim lanes; chronic harassment shows up as nipped tails, frenetic pacing, or refusal to bask. The Tank Checker uses a Stocking Pressure Index (SPI) that scales the turtles’ size and count against the tank’s surface area to flag risk levels.
| Species | Solo adult | Pair viable? | Temperament notes |
|---|---|---|---|
| Slider / Painted | 40B (wide) short‑term → 75g+ long‑term | Often no; watch aggression | Active swimmers; defend basking. |
| Musk / Mud | 40B can work for a single adult | Sometimes, width matters | Bottom walkers; prefer cover and width. |
| Reeves | 40B wide footprint minimum | Borderline | Shorter swimmers; benefit from more width. |
| Map | 75g recommended | Rarely | Strong swimmers; like current and room. |
Red flags: frequent nips, chronic hiding, daily ammonia despite water changes, escalating basking disputes. Fixes: reduce headcount, introduce a divider, upgrade to a wider footprint, or run an outdoor pond rotation.
Mistake #2 — Footprint ≠ Gallons
Length × width dictates swimming lanes, turning radius, and oxygen exchange. Two 75‑gallon tanks can behave differently: the short, tall one feels cramped compared to a low, wide design. Use the Footprint‑to‑Shell Ratio (FSR) in the Tank Checker to compare against species‑specific targets.
| Group | Length ≥ | Width ≥ |
|---|---|---|
| Slider / Painted | 8–10 × shell length | 5–6 × shell length |
| Musk / Mud / Reeves | 6–8 × shell length | 4–5 × shell length |
| Map | 9–10 × shell length | 5–6 × shell length |
Mistake #3 — Underestimating Evaporation
Evaporation drops the waterline, risks exposing heaters and causing filter cavitation, and leaves mineral crust. Rate depends on surface area, temperature difference, humidity, airflow, and lids. The Checker estimates liters per day and mm/day waterline drop so you can plan top‑offs and choose covers.
| Footprint (cm) | Uncovered (dry) | Mesh (normal) | Glass lid (humid) |
|---|---|---|---|
| 40B (91×46) | 1.2–2.0 | 0.8–1.2 | 0.3–0.6 |
| 75g (121×46) | 1.6–2.6 | 1.0–1.6 | 0.4–0.8 |
| 120g (122×61) | 2.0–3.2 | 1.3–2.1 | 0.6–1.0 |
- Mitigation: partial covers, move lamps to reduce drafts, increase sump level, add float‑valve, schedule weekly top‑offs.
- Safety: GFCI, drip loops, keep heaters submerged even as waterline drops.
Worked Examples
Solo juvenile slider
A 20‑long seems okay on paper, but its narrow width compresses turning. A 40 breeder’s wider footprint buys you a comfortable season; plan a 75‑gallon upgrade as shell length approaches mid‑teens (cm). Expect evaporation around 1–2 L/day uncovered in a dry room.
Two adult musk turtles
Prioritize width. A 40 breeder with shallow ramp and deeper swim zone can work if individuals tolerate each other. Monitor SPI monthly and prepare a divider or second enclosure.
Adult Reeves in hot, dry room
Evaporation spikes with high delta‑T and low RH. Use mesh or partial glass lid, pre‑mix top‑off water, and set a 2–3 day top‑off routine to protect heaters and filter intake.
How to Measure, Compare, and Mitigate
- Measure footprint: length × width in centimeters; multiply to get surface area.
- Check FSR: divide length and width by largest shell length; compare to the table above.
- Estimate evaporation: run the Checker and plan a weekly top‑off volume.
- Set turnover: pick a filter that circulates 4–8× the filled volume per hour; avoid excessive jetting.
- Re‑audit monthly: juveniles grow—today’s fit can be next season’s squeeze.
Downloads & Tools
- Export your Tank Checker results as CSV (top bar).
- Print this page as a PDF (top bar) — print styles included.
- Copy a shareable link with your inputs encoded (top bar).