thanks tony & super,
what i mean is that the design of the dupla CO2 defuser has a water input hose(incoming water dissolve the CO2 in the defuser and flow into the tank through the defuser), suppose my Luwel tank's standard filter pump has a output hole to output water to the Dupla defuser , but the output hole of the filter pump drawing water from the defuser instead of pouring water into the Dupla defuser, that cause the dissolve action can not be done inside the Dupla defuser. Now I have to use a different pump to pump water into the Dupla defuser, instead of using the hole provided by the Luwel Filter pump....Am I doing something wrong or it is the design? Sorry for using such poor english cause my chinese writing board is not functioning well
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