What to Do if Your Aquarium Isn’t Level

🐟 What to Do if Your Aquarium Isn’t Level

Water Weight: 1 gallon ≈ 8.34 lbs → even a 55-gallon tank weighs ~450 lbs without substrate/rocks.
Uneven Pressure: If one side is lower, the glass seams and silicone joints are under unequal pressure.
Risk: Over time this can cause leaks, cracks, or catastrophic failure.

Use a carpenter’s bubble level across the front, back, and sides.
✅ Acceptable tolerance:
- Up to 1/8 inch (3 mm) off across the tank length is usually fine.
🚨 Danger zone:
- 1/4 inch (6 mm) or more = needs correction before filling/keeping long term.

Stand: Is it flat? Cheap particle board stands often sag in the middle.
Floor: Hardwood, carpet, or basement floors can slope.
Settling: After filling, tank weight can compress carpet or flooring unevenly.

If the Tank is Empty or Partially Filled:
- 🧱 Use plastic shims (never wood → swells with water).
- Place them under the stand, not directly under the tank glass.
- Insert shims on the low side, gently tap until the stand is level.
If the Tank is Already Full:
- 🪣 Drain at least 50–75% of the water before adjusting.
- Trying to shim under a fully loaded tank can crack the glass.
Full Support Needed:
- If stand legs don’t sit flat, place a sheet of ¾” plywood under the whole stand. Shim under the plywood → distributes pressure evenly.
Rimless Tanks:
- Must have 100% bottom support (no gaps). Use a leveling mat/foam pad between tank and stand to absorb micro-unevenness.

On Carpet: Tank will settle after filling. Always re-check level after 24–48 hours. Add shims if needed.
On Concrete Basement Floor: Floors may slope toward a drain. Best fix = plywood base + shims.
Large Tanks (75g+): Weight amplifies problems. Even 1/8” off becomes dangerous. Always correct before fully filling.