Tetra Plant Co2 Optimat

Could you tell us if the pocket of gas left each evening in the diffuser pipe of the Tetra c02 Optimat, which your instruction manual says is oxygen and nitrogen, would be harmful to fish or plants if left unvented. The reason for the question is the position of the diffuser pipe in our aquarium is not easy to get to, and therefore turning it upside down to release this gas pocket is very difficult. When the diffuser pipe is filled each day does the new CO2 gas push out the remaining oxygen and nitrogen gas from the day before? We note in the instruction manual it says the diffuser pipe must be placed 5 to 15 cm below the surface of the water. But there is no explanation as to the effects of placing it 5 to 15 cm below the water. Does the tube Empty quicker at five then it does it 15 etcetera?

Dear Mr Bertram, Thank you for your question The nitrogen and o­xygen gases that can accumulate in the CO2 diffusion pipe are certainly not harmful to fish. 70% of the air we breathe is nitrogen gas, which is inert. Fish can experience problems with gas supersaturation but this only occurs when large quantities of gas are forced into the water, or when groundwater is brought to the surface quickly which does not allow the gases time to depressurise. Neither of these circumstances are relevant here. The only issue the presence of these gases in your diffuser could cause would be that they could displace the CO2 thereby lowering the effective dose into the tank with each application. Regarding the placement of the diffuser in the tank, the 5-15cm depth is optimal, too high and too much of the CO2 gas can be lost to the air at the surface, too low and the elevated water pressure increases the loss of CO2 from the diffuser. Hence our trials have shown that the quoted figures were optimal. Should you wish to contact us further or to place an order, please call us on 0121 355 7701. Thank you for using our online Q&A system. Kind regards Dan Everton