glutaraldehyde

[Sheraaz Essak]

Has anyone got any feedback on this product from "Aqua design" I usually look at the % of glutaraldehyde in a product I'm buying, as nothing was stated on the label or website, I emailed the company asking for some basic information, I.e the glutaraldehyde percentage used in their product. Unfortunately they weren't willing to disclose the % claiming their formula is a secret which has raised doubts on the effectiveness of their product.

Anyone that's actually used this and has some feedback, I'd really appreciate it, thank you in advance.

 

[tiger15]

Your math is correct in that 1.22 ppm_molar CO2 in water is equivalent to 3 mg/l. But molar fraction is not concentration, not equivalent to ppmv (by volume) in water, and not appropriate for concentration comparison between two media. Gas concentration in air is expressed in ppmv or ug/m3 by weight. By volume or weight refers to the numerator, not the denominator which is in volume. Since Avogadro Law is not applicable to liquid, I don’t think ppmv in water is definable.

Reference this link if you are still confused. Parts Per Million (ppm) Converter

Although molar fraction is not a concentration/density measurement, it defines the partial pressure of a gas over water which greatly affects its diffusion, solubility and biological activities. The reason CO2 diffusion rate in air is many times greater than in water is due to its higher molar fraction. I guess this leads to the same conclusion that there is no greater concentration of CO2 in air than in water, and the difference of uptake rate is due to greater diffusion activities.

 

[hax47]

I think that the above discussion proves my point, that the ppm is confusing 🙂. Of course, once we understand it, even the most complex particle physics isn't complicated.

I guess this leads to the same conclusion that there is no greater concentration of CO2 in air than in water

Indeed, while accurate, it's common for individuals to perceive atmospheric CO2 at 400 ppm as "a lot" compared to 2-3 ppm in water due to the apparent similarity in units.

I think that plants care about partial pressure

Although molar fraction is not a concentration/density measurement, it defines the partial pressure of a gas over water which greatly affects its diffusion, solubility and biological activities.

We can use CO2 partial pressure (pCO2) not just in air above water, but also in water. It is directly comparable, the higher value means "more". The difference between these values can be used to determine the CO2 diffusion between air and water, water and plant tissue, or air and plant tissue. The partial pressure difference is directly proportional to the CO2 diffusion flux and determines the direction of diffusion.

and the difference of uptake rate is due to greater diffusion activities.

I agree, in the end, we don't only care about the "how much", but also about the availability which also depends on diffusion rates and convection (water or air circulation).

 

[tiger15]

I think that the above discussion proves my point, that the ppm is confusing 🙂. Of course, once we understand it, even the most complex particle physics isn't complicated.

Indeed, while accurate, it's common for individuals to perceive atmospheric CO2 at 400 ppm as "a lot" compared to 2-3 ppm in water due to the apparent similarity in units

I agree. ppm is confusing as it depends on the unit of reference, and ppmv is the worst. You have to imagine that gases in air can be partitioned into separate volumes so the ppm ratio can be calculated. In reality, gas molecules commingle in the air space and can only be separated in the Lab. ppmv is not definable for liquid and solid, and is applicable to air only due to the Avogadros Law.