M

#### Marcel G

##### Guest

**how much carbon (or CO2) we can gain from glutaraldehyde**, and if we can use it as an equivalent substitute for pressurised CO2.

I tried to do some calculations, and find out the following:

The molecular formula of

__(GA) is C5H8O2. From this we can calculate, that 5 ml of__

__Glutaraldehyde__*1.5% solution of GA*(recommended dose for 100L tank) = 0,075g C5H8O2 = 0,045g C,

*which is equivalent to*0,165g of CO2 = 165 mg CO2. So in 1 recommended dose we add 165 mg CO2 into 100L tank, which is only about

**2 mg/L CO2 per day**. In case my photoperiod last 10 hours, then I supply my plants with 0.2 mg/L CO2 each hour.What do you think? Could this be sufficent for our plants? To me it seems that GA is very poor substitute for pressurised CO2.

How much

__do your plants really need? This you can calculate by measuring the consumption of nitrates (NO3). If you measure the nitrates' concentration in your tank today, and compare it with the concentration measured on the following day, you will find out the amount your plants consume in one day. Let's say, your plants consume__

__CO2__**1 mg/L NO3 per day**. In 100L tank it means 100 mg NO3 (= daily consumption of NO3 in your tank) = 22.6 mg of nitrogen (N). As we know in the plants' dry matter there is about 45% of C, and 2% of N (approximately), which makes a ratio of about

**20:1 (C:N)**. So if my plants use up each day 22.6 mg of N, then we can calculate, that they use up also 452 mg of C = 1655 mg of CO2 =

**16 mg/L of CO2 per day in 100L tank**. But if your plants use 2 mg/L of NO3 per day, then they will need 32 mg/L of CO2 per day in 100L tank, etc. Compare this with the amount of C (which we translated into CO2) in one dose of glutaraldehyde, which is 2 mg/L per day in 100L tank.

**Plants need**:

__16 mg/L of CO2__(maybe more > depends on the numbers and hunger of your plants)

**Pressurised CO2 gives us**:

__30 mg/L of CO2__constantly (or whatever concentration you want)

**Glutaraldehyde gives us**:

__2 mg/L of CO2__(in one dose)

PS: Glutaraldehyde is the main component of the following commercial products:

**Seachem Flourish Excel**,

**Easy-Life EasyCarbo**, or

**PlantaGrow PMFE**.