Low-iron glass has increasingly become a popular upgrade for pond glass windows, especially among koi pond owners looking to experience the full benefits of low-iron glass. It offers the clearest possible view into the pond by reducing the greenish tint that naturally appears in standard glass, particularly as thickness increases. Designed to deliver a cleaner, brighter, and true-to-life view, low-iron glass enhances the appearance of your pond, fish, and overall water clarity. This guide explains how and why low-iron glass performs so well in pond environments, and whether it is the right choice for your setup.
What is low-iron glass?
Without getting too technical, the process involves using low-iron silica sand and a tightly controlled melting process to minimise iron oxidation. Reducing the iron content during production creates what’s often referred to as extra clear glass or reduced green tint glass. This process reduces the glass's iron content to around 0.01% compared to standard glass, which has 0.1%. As for the appearance, standard glass tends to have a green hue from the iron content, whereas low-iron glass removes this tint, giving accurate colour and preventing discolouration.
What are the main benefits of low-iron glass for a pond glass window?
High clarity
Low-iron pond glass allows up to 91% more light transmission than standard glass and adds the maximum brightness of any pond glass available.
Neutral colour
Removes the green hue from the edges, providing a clearer, more neutral appearance and a more accurate view of the underwater life.
Enhanced transparency
While all glass is transparent, the lower iron levels in low-iron pond glass enhance the overall transparency.
Accurate colour
Prevents colour distortion, making it perfect for koi fish ponds to showcase the vibrant shades of the fish.
Clarity in thicker panels
Ponds with a higher water volume require thicker glass, but thicker glass can have a more pronounced green tint. Low-iron glass maintains its clarity even in thicker, laminated sections.
Durability and scratch resistance
Both low-iron and standard glass offer excellent scratch resistance, a significant advantage over acrylic, which can easily haze and micro-scratch with cleaning.
Why is the difference more noticeable with thicker glass?
The iron impurities in standard glass absorb more light as it travels through the material, which can make the natural greenish tint more visible, where it would be more subtle in thinner glass. As low-iron pond glass has reduced iron content, it maintains its superior clarity and true colour even at greater thicknesses.
The colour is dependent on the way that light travels through the different materials; in thicker glass, light travels a longer distance through the iron-infused material, making the green tint more pronounced, specifically on the edges. Low-iron pond glass reduces this effect.
Is low-iron glass the same as low-iron toughened glass?
They are not the same, but have similarities.
- Low-iron glass refers to the composition and clarity of the glass. It’s about reducing the iron content to improve transparency and colour accuracy.
- Toughened glass (also known as tempered glass) refers to a heat-treatment process that increases the strength and safety of the glass.
For pond applications, these two features are often combined. Low-iron toughened glass gives you the best of both worlds: enhanced clarity and the strength required to handle water pressure and outdoor conditions.
When is low-iron glass worth it?
Because of the added benefits of low-iron glass, it can typically cost more than a standard glass pond window. That said, there are a few considerations to take into account when deciding between the two:
- For koi fish ponds, low-iron glass works exceptionally well in showcasing the vibrant colours of the fish without distortion.
- If your pond requires thicker glass, we recommend investing in low-iron toughened glass due to the green tint becoming more prominent in thicker glass. The volume of your pond will determine the thickness of the glass needed. We have a guide you can follow for this.
- If the pond window is going to be a focal point of your garden, extra clear low-iron glass offers a premium, high-quality finish that creates a key design feature in your garden.
For small, shallow ponds, standard glass can be perfectly adequate, but for larger installations where clarity is a priority, low-iron glass can make a visible, lasting difference.
Choosing the right pond glass window
It’s more than just choosing between standard and low-iron pond glass; the size of the pond will determine the thickness of the glass you choose. We recommend the following:
21.5mm - up to 400mm deep and 1400mm wide
25.5mm - up to 550mm deep and 1600mm wide
33mm - up to 900mm deep and 2000mm wide
39mm - up to 1200mm deep and 3500mm wide
44.5mm - up to 1200mm deep and 3500mm wide
We have a range of options available at House of Ponds. Explore our collection today to find the perfect fit for your pond. All our products are made to order, so you get the right measurements and thickness the first time around. For added pond safety and surface protection, shop our additional products, such as pond jump guards, which can help prevent fish from jumping out of open or raised pond areas.
If you're looking to get the clearest view of your pond’s underwater life, low-iron glass is the most effective upgrade you can make. Browse our options or get in touch with our dedicated team through our contact page with any further questions.
