We have developed a range of manually-fed, flexible low cost digester suitable for those projects when budgets don’t stretch to fund automatic feeding digesters, or this capability may not be required for specific projects. Since, up to now most AD research has been done using manually fed digesters, some researchers may want to continue that practice. Our hybrid semi-batch reactors provide manual feeding capability with gas-tight continuous digestate collection, independent mixing and automatic gas flow measurement. Leak-free dosing or sampling is available for all reactors, and handling is simple. The temperature can be set digitally in our Grant water baths. Two models: the Pegasus system has 3 x 5 litre digesters, and The Phoenix system has 6 x 2 litre, both require a small surface area and are low cost for the semi-continuously fed digester capabilities they offer. Low cost, high quality research capability.