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Please explain CO2 usage, in detail

959 Views 3 Replies 3 Participants Last post by  Raymond S.
Sorry if this is in the wrong forum but I didn't see a high tech forum.

I'm new to planted to tanks and will be changing my 75 gallon over, hopefully this weekend.

I've been reading everything I can find to learn and keep reading that if I want my plants to grow well and have a few red ones, I need CO2. I have no idea where to begin.

Please explain what I would need in equipment, is it dangerous, cost, how to set it up and I also understand that the water parameters must be adjusted for CO2.

I'm not sure I want to go this route but I want to learn before making a decision.

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In planted aquariums we are trying to help the plants grow at the right rate.
Some of us want the plants to grow fast, or to grow delicate plants.
Some of us want the plants to grow slower (less pruning) and are OK with average sorts of plants.

In nature some water dissolves certain minerals, and organic matter decomposes and other things happen so that the water is fairly high in CO2. Streams that are fed by underground source water are often high in CO2.
Plants that grow under these conditions often cannot live when the water is lower in CO2. These are the 'delicate' plants that many people find challenging to keep. If you are looking at plant lists these will be listed for experienced plant growers.

It is entirely possible to have a very nice tank, lots of thriving plants, and not have to add CO2 in any form.
The secret is this:
Plants use about a dozen elements in various ratios.
They need more of some things, less of others. These ratios do not change.

If the plants are growing in high light then they need lots of everything, but still in those same ratios.
If the plants are growing in low light then they do not need very much of everything, but they still need all the elements.

When you are asking about fertilizer or CO2 or anything else you need to start with:

1) What do my plants need?

And follow it up with:

2) What am I already doing that meets any part of this need?


Fish food can supply quite a lot of the elements plants need, but only enough for a low tech tank. And fish food does not supply these things in exactly the right ratio. Even in a low tech tank it usually helps to dose potassium and iron.

Fish food does not supply enough of everything to keep a high tech tank going. It is pretty much counted as zero in these tanks. The same as running a tank with no fish. You need to supply all the elements plants need, and in something approaching the right ratios.

For low tech tanks there are low tech ways to supplement the CO2, if it is needed at all. It can help.
DIY yeast/sugar is one method. This seems to work well for tanks under 29 gallons, and can even work for larger tanks, but it is more work.
Excel and similar products can work. They can cost a bit when you have a large tank or many tanks.

For high tech tanks pressurized CO2 is the way to go.
~More consistent levels.
~One major expense to set up, then much cheaper than the other methods.
~A lot less work.

The equipment is a bit complex, so read the details, but a basic rundown is this:
Pressurized CO2 is purchased in canisters that are designed to contain that pressure. When they are handled correctly they are safe.
The CO2 is released by special valves that control the release so it happens very slowly.
The CO2 is sent through tubing to a diffuser. This breaks up the stream of CO2 into tiny bubbles. The diffuser can be in the tank or under the tank, and fed through the filter.
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Thank you, Diana.

Can I grow a few red plants in low tech?

When you said fish food feeds plants, do you mean the actual food fed to fish or the waste the fish produce?

After reading your response, I know I want to do low tech.
Actually it's both. The food contains some Phosphates and the waste not only breaks down into nutrients but the process of breaking down produces ammonia which the plant use.
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