lastlight's 101 half cube

[Delphinus]

I think in <1/2" glass you don't really need go to low-iron. At 1/2" it's 50/50 and if you're going >1/2" then it's probably worth it. I notice the difference in 1/2", but that's me.

If clarity is really an issue then you should consider acrylic because it's even more optically clear than low-iron glass. But it's even softer, so will scratch way easier. And you have to brace the heck out of the tank. But on the plus side you can buff the scratches out of acrylic.