Can lime in gravel affect CO2 dosing?

[kajaksurfa]

Hello,

In my 500 liters aquaria i use "english pea gravel" in 2-5 mm size as a bottom substrate.
(I know, it's terrible, but that's what I had handy at the moment)

It was previously used as a substrate for Malawi chichlids and therefore have a few ponds of crushed limestone
gravel in it to raise pH.

Now I use the same aquarium for an Asian biotope aquarium. I am not looking for this tank to be all covered up with
plants but, I want my plants to look fresh so I added CO2 fertilization via a 6kg fire extinguisher bottle and
a CO2 reactor. Timer set CO2 ON/OFF simultaneusly with light.

Main plant is Java ferns growing on roots and some Cryptocorynes and little Java moss.

I took some 1 week old aquarium water to the municipal testlab and got pH 7.2 / kH 6 which is very similar as the tap water.

In what way can I expect the limestone gravel to affect Co2 dosing...if any?

I see Oxygen forming on the leaves after about five hours of lighting (of tot 10 hrs/day)

No signs of stress on the fishes.

Regards, Leif

 

[ceg4048]

Hi,
Evidently there is a minor loss of CO2 solubility as the hardness increases but not anything you will be able to detect in practical terms. It's just that the final pH value will rise, which is to be expected. It's not enough to worry about.

As your plants grow you might find it better to turn on the gas an hour or so before the lights. This is standard procedure to ensure better CO2 saturation by the time the lights go on. You can then turn it off earlier as well.

Cheers,