Aqueon 20-Gallon Glass Aquarium
$$Standard rectangular glass tank — the default. Drops into any 20-gallon-sized stand, accepts standard hoods and lighting. The baseline starter tank.
Almost every aquarium sold today is glass. Walk into any pet store and you'll see a wall of glass tanks in standard sizes; acrylic is the niche material reserved for custom builds, very large tanks, and specific use cases. There's a reason for that — glass is cheaper, scratch-resistant, and good enough for most aquarium needs. But acrylic has real advantages worth understanding before you commit.
The headline differences
| Factor | Glass | Acrylic |
|---|---|---|
| Cost (standard sizes) | $$ — significantly cheaper | $$$$ — 2–3× more for the same volume |
| Weight | Heavy — limits practical size to ~125 gal | ~1/2 the weight of glass |
| Clarity | Excellent; slight green tint at thicker panels | Crystal clear; no tint |
| Scratch resistance | Excellent — algae scrapers safe | Poor — scratches from sponges, sand, and substrate |
| Shatter resistance | Will crack from impact | Won't shatter — bends instead |
| Custom shapes | Limited — rectangular standard | Easily molded into curves, cylinders, custom shapes |
| Yellow over time | No | Slight yellowing in older budget acrylic |
| Repair | Crack = total loss | Scratches can be polished out |
Where glass wins
Cost. A standard 20-gallon glass tank is significantly cheaper than the acrylic equivalent. Multiply across a 75-gallon or 125-gallon build and the cost gap becomes considerable.
Scratch resistance. This is the deal-breaker for many aquarists. Glass tolerates any algae scraper, any cleaning sponge, sand stirring with bare hands, and accidental contact from a net. Acrylic scratches if you use anything more abrasive than a soft microfiber cloth — and one bad cleaning session can leave permanent marks.
Optical clarity over time. Modern glass stays optically clear indefinitely. Some budget-brand acrylic yellows slightly after 5–10 years, particularly in tanks with strong lighting.
Standard sizes everywhere. Every major pet retailer stocks glass tanks in standard sizes (5, 10, 20, 29, 55, 75 gallons). Replacement parts (lids, hoods, stands) are designed around standard glass dimensions. Acrylic is special-order.
Where acrylic wins
Weight. A 75-gallon glass tank weighs ~140 lbs empty. The acrylic equivalent is ~70 lbs. For anyone moving a tank, building above the ground floor of an apartment, or putting a tank on a piece of furniture that isn't rated for absurd weight, this matters.
Impact resistance. Acrylic flexes under impact instead of cracking. If a child throws a toy at the tank, or you drop a heavy decoration during cleaning, acrylic is dramatically more forgiving than glass. Tanks with kids or pets nearby often justify the acrylic premium for this reason alone.
Shape flexibility. The most striking visual aquariums — bow-front displays, corner tanks, cylindrical pillars, curved-front tanks — are almost always acrylic. The manufacturing process molds easily; glass would require complex glue joints that are weaker and uglier.
Insulation. Acrylic insulates ~20% better than glass. In cold climates, this can mean lower heater wattage and slightly more stable temperature.
Large tank viability. Tanks over 200 gallons in glass become impractical — the panel thickness needed to hold the water pressure is extreme. Public aquariums and large custom installations are almost universally acrylic for this reason.
SeaClear 20-Gallon Acrylic
$$$Standard acrylic equivalent at premium pricing. Lighter, more impact-resistant, scratch-prone. Suitable for renters worried about leaks or families with kids near the tank.
Innovative Marine NUVO Fusion Pro 10
$$$$Premium rimless acrylic AIO nano aquarium. Display-grade clarity, hidden filtration, integrated lighting. The acrylic answer to the Fluval Spec V.
The scratch problem
The single biggest reason aquarists choose glass over acrylic is the scratch issue. Acrylic scratches from things you don't think of:
- Algae scrapers (use only acrylic-safe pads, never metal blades)
- Sand grains caught in a cleaning sponge
- Substrate stirred against the inside wall
- Suction cups removed too quickly
- Fingernails during routine cleaning
- Snails with hard shells against the glass (sometimes)
Mild scratches in acrylic can be polished out with a specialized acrylic polish, but the process is tedious and can't fix deep gouges. Glass simply doesn't have this problem under normal use.
What about the green tint?
Standard float glass has a slight green tint when viewed edge-on, which is most noticeable in thicker panels (75+ gallons). For aquarists who care, low-iron glass (sometimes labeled "starphire" or "ultra-clear") eliminates the tint at a significant cost premium. Most beginner and mid-range glass tanks use standard glass; the tint is barely noticeable in normal viewing.
Acrylic has no tint regardless of thickness, which is part of why public aquariums use it for very large displays.
The honest call by use case
| Use case | Pick | Why |
|---|---|---|
| First tank, any size | Glass | Cost, scratch resistance, standard sizing |
| Family with young kids | Acrylic | Impact resistance worth the price |
| Apartment above ground floor | Acrylic | Weight + impact resistance both matter |
| Custom shape (cylindrical, bow-front) | Acrylic | Glass impractical for non-rectangular shapes |
| Display aquascape | Glass (low-iron if budget allows) | Optical clarity over time + scratch resistance |
| Very large tank (200+ gallons) | Acrylic | Weight and panel thickness make glass impractical |
| Coldwater climate | Acrylic | Slight insulation benefit |
For tank-size considerations and gear pairing, see our setup guide. For starter kits in both materials, see our starter kit roundup.
FAQs
Is acrylic worth the extra cost over glass?
For specific use cases (families with kids, very large tanks, custom shapes, apartments above ground floor) — yes. For a standard rectangular display tank, glass is the better default.
Can you polish out scratches in acrylic?
Mild surface scratches yes — using specialized acrylic polish (Novus or similar) and progressive grit pads. Deep gouges or repeated abrasion damage often can't be fully removed. Better to avoid scratches in the first place.
Does acrylic yellow over time?
Some budget-brand acrylic yellows slightly after 5–10 years, particularly under intense aquarium lighting. Premium acrylic brands include UV inhibitors that prevent this. Glass doesn't yellow at all.
Are acrylic aquariums safer than glass?
More impact-resistant — acrylic flexes rather than shatters. But "safer" depends on context. For a household with kids or pets near the tank, acrylic is genuinely safer. For routine use, glass is reliable enough that the question doesn't come up.
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