Low-iron glass

Low-iron glass is aquarium glass manufactured with a lower iron content than standard soda-lime glass, which is what normally gives thick glass panels a faint green tint when viewed from the side. With less iron in the mix, the glass looks nearly colorless even at the thicker panel sizes used for larger aquariums, which many aquascapers prefer since it lets plant and hardscape colors come through more accurately.

The clarity difference is most noticeable on larger tanks or in bright light, where standard glass panels can visibly shift colors toward green, especially along the front pane and corners. Low-iron glass is common on rimless, cube-style and other display-focused aquariums where the tank itself is meant to disappear visually and let the aquascape be the focus, rather than on utility tanks kept in a fish room.

Low-iron glass usually costs more than standard glass and can be more prone to visible scratches since any mark shows up more clearly against the clearer background, so a soft algae scraper and care during cleaning matter more than with a standard tank. A common mistake is assuming all rimless tanks use low-iron glass by default, when many budget rimless models still use standard glass, so it is worth checking the specification rather than the tank style alone.