I have given the sump its own page in order to give details about what I think is a pretty good design.

I wanted a number of things from my sump. Firstly and most importantly, I wanted most of the equipment to stand inside it so as to remove the worries of leaks, thus it needed to be as large as possible. Given that I need space for the two Deltec external return pumps (they are effectively modified Grundfos pumps a little like Quiet Ones), the sump ended up 76cm (30") by 61cm (24"), with a height of 38cm (15"). Two holes were drilled at the rear of the two side panes to provide the inlet to the return pumps. I would have preferred to have return pumps in the sump as well but its difficult to get hold of 4000lph (around 1000 gallons per hour) pressure rated pumps that can be submerged.

The sump is divided equally into three using one 30cm and one 28cm high panes of glass. The middle third is the home of the deep sand bed (DSB) and live sponge filtration area. Water is pumped into the DSB via the output of the skimmer. In some respects it would have been better to have "unfiltered" water enter the DSB region but this is the most convenient manner and everything seems happy.

In the left-hand third I have the skimmer, it's feed pump, a heater, and the feed pump to the chiller. In the right-hand third, I have another heater, the calcium carbonate reactor and the kalkwasser stirrer. At the rear of both the outer thirds I have a sloping baffle to try to protect the return pump inlets from small bubbles.

This pretty much is a full as my sump can get.

The tank water comes via the weirs, via 25mm (1") ID piping to the front of the sump.