CO2 Tablets for Aquarium Plants — 60-Tablet Bottle

A simple, low-cost carbon boost for low-tech planted tanks — drop-in tablets, no cylinder or regulator.

Pressurised CO2 gives the best results in a planted tank, but a full cylinder, regulator, and diffuser is a real investment and a lot of setup for a small or low-tech aquarium. These effervescent CO2 tablets are the low-effort alternative: you drop a tablet into the tank and it releases carbon dioxide into the water, giving your plants a modest carbon top-up without any hardware. For a nano tank, a low-light setup, or a beginner planted tank running easy plants, that can be enough to nudge growth along. Set your expectations correctly and it's a genuinely useful, inexpensive tool — just don't expect it to match a pressurised system on a demanding, high-lightscape.

Why Aquascapers Choose These Tablets

• 🔧 Zero equipment — no cylinder, regulator, solenoid, or diffuser. Drop a tablet in and you're done, which makes carbon supplementation accessible for tiny and low-tech tanks.
• 💰 Low cost of entry — a fraction of the price of a pressurised CO2 kit, so it's an easy way to test whether a little extra carbon helps your plants before committing to a full system.
• 📏 Simple dosing — roughly one tablet per 20 litres (about 5 gallons) of water, once or twice a week. Easy to scale to your tank size.
• 🌱 Aimed at easy, low-light plants — the kind of modest carbon boost that suits mosses, Anubias, Java fern, and undemanding stem plants in a low-tech setup.
• 🪫 Set-and-forget format — no daily bubble-counting or pressure checks; you dose on a weekly rhythm.
• 🧪 Good starter tool — a low-risk way for a new hobbyist to learn how their plants respond to added carbon.

⚠️ This is a supplement, not a pressurised-CO2 replacement. The supplier markets these directly against CO2 cylinders, but be realistic: a tablet delivers a brief, low-level release, and dissolved CO2 escapes at the water surface quickly. On a high-light, high-demand scape it will not produce cylinder-level results or prevent CO2-limited algae. Treat it as a gentle boost for low-tech tanks, not a fix for a carbon-hungry aquascape.

⚠️ Go slow with shrimp and in small or soft-water tanks. Adding CO2 lowers pH, and a sudden change stresses livestock — shrimp especially. Start with less than the suggested dose in a nano or shrimp tank, watch your animals, and don't chase results by overdosing. If in doubt, dose lightly and observe over a week.

💡 Pro tip: surface agitation drives CO2 straight back out. The supplier suggests placing a tablet in your filter "for better results," but strong surface movement and filter outflow actually outgas CO2 faster, wasting most of it. For the little CO2 these tablets give off to do any good, place the tablet low in the tank near the plants and, if anything, reduce surface turbulence while it releases — don't feed it through a filter with a churning surface.

💡 Pro tip: dose in the morning, with your lights. Plants only use CO2 while they're photosynthesising, which is during the light period. Dosing at lights-on puts the brief carbon release where the plants can actually use it, rather than losing it overnight.

Specifications

What's in the Box

• 1 × bottle of 60 CO2 tablets

Nothing else is required to use them — no diffuser, holder, or dosing tool is included or needed. This is the 60-tablet size; 30- and 100-tablet bottles are separate options.

Pairs Well With

• Root tabs/substrate fertiliser — carbon is only one input; root-feeding plants also want nutrients at the roots for real growth.
• Liquid all-in-one fertiliser — pairs with a carbon boost to cover the macro and micro nutrients tablets don't provide.
• A drop checker or pH/KH test lets you actually see whether the tablets are moving your CO2 or pH, instead of guessing.
• Easy low-light plants (moss, Anubias, Java fern) — the plant types best matched to the modest carbon these tablets supply.

Your Top 5 Questions — Answered

1. Do these really work as well as a pressurised CO2 system?

= No — and it's worth being clear about that. A pressurised cylinder delivers a steady, controllable dose of dissolved CO2 that these tablets can't match. A tablet gives a brief, low-level release, and much of the CO2 escapes at the surface before plants use it. For a low-tech, low-light tank with easy plants, that small boost can still help. For a high-light, carbon-hungry aquascape, a pressurised system is the right tool. Buy these for what they are: a cheap, no-equipment supplement.

2. How many tablets do I use, and how often?

= Roughly one tablet per 20 litres (about 5 gallons) of water, once or twice a week. Scale to your tank — a 10-gallon tank would take about two tablets per dose. In a small, soft-water, or shrimp tank, start below that and see how your plants and livestock respond before increasing.

3. Are they safe for fish and shrimp?

= Used sensibly, yes, but with a caveat: adding CO2 lowers pH, and a fast pH swing stresses fish and especially shrimp. The risk comes from overdosing, not from the tablets themselves. Dose conservatively, avoid dumping several tablets at once into a small tank, and keep an eye on your animals. If you keep sensitive shrimp, start with a partial dose.

4. Where should I put the tablet — in the filter?

= Not the filter, despite what the packaging suggests. Filter flow and surface agitation drive CO2 out of the water faster, so running a tablet through your filter wastes most of it. Place the tablet low in the tank, near your plants, and reduce surface turbulence while it releases so more of the CO2 stays dissolved where the plants can reach it.

5. What are they actually made of — is it "solid CO2"?

= Not literally. Solid carbon dioxide is dry ice; that's not what this is. These are effervescent tablets that release carbon dioxide gas when they dissolve in water, similar in principle to any fizzing tablet. Ignore the "extracted from natural plants" marketing — what matters is that they give off a small amount of CO2 as they dissolve. They're intended for freshwater planted tanks.

Ships within 20–25 business days.