Liquid co2

Country joe

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On another forum someone was saying what a difference liquid co2 has in keeping his algae down, I've read its a complete waste of money, but he goes on to say, when he stopped using it, he noticed a difference in his algae situation, what do you think good product, or snake oil.
 
It works a bit to control algae, I have tried it some time ago, but it also poisonous, so dosage is very important. I do not know what the long term effects would be on your fish. With algae I find it best to control it with more conventional means, reduce lighting, reduce feeding, and wait the algae out. For me I find I get algae problems when first starting a tank but after about 6 months it is no longer a problem. Some people are very against liquid co2.
 
You don't need additional CO2 in most tanks because there's plenty in the water and it's produced continuously by the fish and filter bacteria.

If you have an algae problem, look at what is causing it. Algae grows from excess light or nutrients, or not enough live plants to use the light and nutrients.

If there's too much light or the light is on for too long each day, try reducing it.

If there's lots of nutrients in the water (either from aquarium plant fertiliser or lots of fish waste and food), reduce the nutrients with big water changes.

If you only have a few live plants in the aquarium, add more live plants to use the light and nutrients.
 
I think of fertilization in an aquarium as a way to control deficiencies.

If there is no apparent deficiencies, I don't add any. A some point the water will be depleted from some elements, deficiencies will appear, while some other compounds are building up.

With water changes and good dosing. I'm able to grow easy plants that would never made it before.

I use a complete fertilizer with Co2 included, formulated for "low-tech aquariums" over a year I probably use less than 1/20 of the prescribed dose.

But still, without it, I would never have an anubia sprouting a leaf in a month. Since I use it as soon as there is a slowdown or new leaf looks like having problems. Now they all crank a leaf per week.

So, on the algae control, the effect is more indirect, If the plant grows they are the one that are making a difference. If the plants are not growing and there is enough competition it can turn into an epic algae bloom.

Fertilizer will encourage plants. Decaying plant matter, food and fish poop will encourage algae. Both are good for plants, but most of the time algae can thrive with an incomplete diet, many plants can't
 
As much as I respect Colin's opinions, he is incorrect about the nitrifying bacteria making CO2. In fact, the exact opposite is the case. The nitrifiers need inorganic carbon. In our tanks the two most common ways for them to obtain this is from CO2 in the water or from the components of KH- carbonates and bicarbonates. The bacteria also need oxygen to function properly.

The nitrifiers live in a biofilm. As oxygen penetrates the film it gets used by an assortment of mircobial life. In some areas the O gets used up and the result is nitrate being created. Because there are also facultative bacteria in the bio-film some of them will be in spaces where the O has been used up but there is nitrate. When this is the case, the facultative bacteria use the nitrate and produce N2 gas. This means they are doing denitrification. Unfortunately, the level of this is not sufficient in most instances to avoid the presence of nitrate in the water. Think of it this way. If in the bofilm there are 100 units of Nitrate being created, the facultative bacteria may consume 5 or 10 of those units and the rest goes into the tank water. The amount of nitrate used is not sufficient to prevent it from building up in the water and we need to be remove it via water changes.

Of course, if one has a specific type of filtration set-up, one can have a greater level of denitrifcation happening. One of the best users or nitrate in our tanks are live plants. If you have a very heavily planted tank especially with faster growing plants and you are adding fertilizer which contains NPK, your are likely adding nitrate to the water for the benefit of the plants.


I have used Flourish Excel for over 20 years in as many as a dozen planted tanks. I have seen absolutely no negative effects on my fish some of which have been in such tanks for 20 years. My understanding of this product is that plants can use it but algae cannot. Further, my dosing was in tanks which contained both shrimp and/or assassin snails. The assassins were there to get rid of the pest snails which obviously were not effected by the Excel.

I dose Excel once a week after doing weekly water changes. I add 3 ml/10 gals. of water. I did not use Excel in the one tank where I had used pressurized CO2.
 

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