Why pressure does not tell you how much CO₂ is left — and why the gauge only drops near the end.
Many people have the misconception that the pressure gauge on our CO₂ cylinder tells us the amount of CO₂ left in the cylinder. However, that is not true. The gauge measures pressure, not volume or weight. The pressure reading will usually only start dropping significantly when the cylinder is almost empty. This post will explain why.
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Last update: 20 April 2026
This is a list of places to top up CO2 for planted aquariums in Singapore. If you have any updates, please message me on my Instagram, ArowanaPlanted.
Bring your cylinder for an instant top-up.
Bring your cylinder and swap it for another. Low chance of getting your own cylinder back again.
Leave your cylinder and get it back filled a few days later.
Comes to your home to top up. Usually on the spot.
There are a few ways to get CO2 for your aquarium. Some shops let you swap your empty cylinder for a filled cylinder, some refill your cylinder on the spot, and others help you send your cylinder to be refilled and let you collect it a few days later. Some hobbyists go to the gas suppliers directly for an on-the-spot or collect-later refill. Many of those who get their cylinder refilled wonder if they are getting back a full cylinder. This article will teach you how to tell.
Read More »Post Views: 279 I’m very excited to share this with the Planted Tank community. For decades, we’ve been estimating our CO2 injection rates with bubble counters. Bubble counters are great at telling us whether our CO2 is flowing, but they are barely helpful when we need to adjust our CO2 flow rate. We usually start with […]
I wrote this post some months ago (Feb 2017, I think), but never published it. The measurements will probably be different now, as I’ve made many changes to the tank since then. However, the general conclusion (for my tank) should be the same: CO2 levels remain pretty stable once they reach peak levels.
Since then, I have recently found extra information that explains why my CO2 is stable and not fluctuating (as far as I can tell). I’ll mention that at the end of the post. Everything in the quote block below was my original post.
Read More »It has been a while since the last update. The arowana is growing well, but the plants can do better. Frankly, the main reason for the lack of updates is the less than ideal condition of the plants and algae situation.
I’ve been getting an alga that forms a film on the leaves and hardscape, then dies and turns brown and hard. Also getting the green dust algae (GDA) on my glass. No one apparently has found a good solution for GDA besides lots of Bristlenose Plecos (BN). WIth my aggro arowana, more algae eaters is not really an option. Would really love to put in 10 more BN, or 2 platoons of Otos.
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Post Views: 82 The arowana is growing nicely but seems to have developed a protruding lower jaw. Was told by Gan of Gan Aquarium that a shrimp diet will cause this due to the calcium in their shells. I am not feeding shrimp, but I was dosing Seachem Equilibrium for Calcium and Magnesium for a while for […]
