Planted Tank Obsessed
Join Date: Jan 2007
Location: ABQ, New Mexico
Just my $.02 on this, but sumps do not always "waste" CO2 as most think. Depending on the filtration being used in a sump will determine a lot of how much CO2 is lost. If you are running a wet/dry filtration where the water is constantly "falling" through your media and into water below, you are in essence creating a waterfall which will in fact create more agitation and release the CO2. However, if you do not have this waterfall effect and your return is submerged, then you will be better off. In addition, you can seal off the top of the sump to combat evaporation and CO2 loss as well.
Sumps are great for hiding equipment, and that is really why I use them. My heaters, pH probe, and CO2 reactor are all in my sump. For me this is much better. Also, as someone else said, they can be made out of a letterbin from Staples or a Rubbermaid tote.
Anyway, just wanted to throw out that sumps are not all bad and can indeed be very efficient with regard to CO2. Once again, just my $.02. Enjoy your tank!