Quick Answer: I've had two glass panels on my workbench for 3 years. One is standard float glass. The other is low-iron. I clean them with the same magnet, the same chemicals, the same schedule. Today, I finally measured the differences. Low-iron is clearer. But it also scratches easier, costs more, weighs more, and chips more. Every advantage has a tradeoff. Here's what 3 years of testing actually showed me.
The two panels have been on my bench for 3 years.
I set them up side by side in 2023. Same size. Same thickness (12mm). Same cleaning schedule. Same magnet cleaner. Same chemicals.
I wanted to see: after 3 years of daily use, what's actually different between float glass and low-iron?
Today, I pulled out the measuring tools. Let me show you what I found.
The First Thing I Noticed: The Scratches
I put both panels under the light. I counted the scratches.
Float glass: 3 fine scratches. All along the bottom edge.
Low-iron glass: 7 scratches. 3 on the front face, 4 along the edge.
That's more than double.
Why? Low-iron glass has less iron oxide in the mix. That's why it's clearer. But it also makes the surface slightly softer. So it scratches easier.
3 years of cleaning with the same magnet? The low-iron panel has more scratches.
That's not a huge difference. But it's there. If you clean your tank every week? The scratches accumulate faster.
The Second Thing I Noticed: The Weight
I picked up both panels.
Float glass: 26.7 kg. Low-iron glass: 27.0 kg.
That's a 0.3 kg difference per panel.
Doesn't sound like much. But for a 6-foot tank with 6 panels? That's 1.8 kg extra total.
The stand needs to hold that extra weight. Most stands are designed for standard glass. If you're using low-iron? Make sure the stand is rated for it.
The Third Thing I Noticed: The Price Tag
I looked up the original invoices.
Float glass (12mm, per m²): $28. Low-iron glass (12mm, per m²): $52.
That's an 86% price premium.
For a 6-foot tank (about 2.5 m² of viewing glass)? That's a $60 difference.
Is it worth it? Depends on the tank. For a premium display? Yes. For a sump? No.
The Fourth Thing I Noticed: The Edges
I looked at the cut edges.
Float glass: the edges are clean. No chipping. Low-iron glass: there are 2 small chips along the edge.
Why? Low-iron glass is slightly more brittle. During cutting and polishing, it chips easier.
That's why the polishing process is more expensive. You need more passes. More care.
If you buy low-iron glass from a manufacturer that cuts corners on edge polishing? The edges will chip. The silicone won't seal properly. It leaks.
The 3-Year Verdict
After 3 years of testing, here's the honest answer:
Low-iron glass is better for visibility.
- 91.5% light transmission vs 83-85%
- Colorless edges vs green tint
- Corals get more light
But it has four real downsides:
- Costs 70-100% more
- Scratches easier
- Heavier per panel
- Chips easier during manufacturing
Every advantage has a tradeoff.
When Low-Iron Is Worth It
Pay for low-iron if:
- It's a premium display tank
- It's over 12mm thick (float glass looks green)
- You're keeping corals (they need the light)
- It's in a living room where people see it
Skip low-iron if:
- You're on a tight budget
- The tank is under 10mm thick
- It's a sump or utility tank
- It's in a dark room anyway
What I'm Not Going to Tell You
I can tell you what the downsides of low-iron glass are. I can tell you when it's worth it. I can tell you when to skip it.
But I'm not going to tell you which glass brand is "the best." I'm not going to tell you how to design the tank structure. I'm not going to tell you how to calculate the glass thickness.
That's not my department. I test the glass. I tell you the pros and cons. You decide.
What We Spec at Ruibit
When we build a custom aquarium at Ruibit, we don't automatically spec low-iron glass on every tank.
We ask: "Is this a display tank? Or is it a sump?"
Display tank? Low-iron on the front panel. Sump? Float glass.
We also tell every customer: "Low-iron is 86% more expensive. It's worth it for the front panel. It's not worth it for the sides and back."
That's what we've learned from 3 years of testing. The customers who spec low-iron on the front panel only? They get the best of both worlds. The customers who spec low-iron on everything? They overpay.
The Two Panels
I'm back at my bench.
The two panels are still there. One float. One low-iron.
After 3 years, the low-iron panel is still clearer. But it has more scratches. It weighs more. It cost more.
That's the tradeoff.
Know it. Then decide.
