Botanicare's trade marked Multi-Res reservoir was designed for the gardeners simplicity in maintenance and performance. Available in 10 gallon, 20 gallon, and 40 gallon sizes. Each Multi-Res reservoir comes with a specially designed lid containing an access port and raised grip. This standard option allows the gardener access to the reservoir without taking the entire lid off the reservoir. This allows for a more functional routine of adding solutions, nutrients, and additives to your reservoir. The Multi-Res also comes equipped with built in bulkhead ports in front and on each side. This standard option allows for the ability to add a centrifugal on pump outside the reservoir. This feature gives you the ability to join reservoirs together in-line or side by side to achieve increased water volume.