Pontoon floats are just one option available for pumps or stirrers on ponds. Mainly used for short shaft pressure pumps which are required to be in the fluid (non self priming). The pontoon needs to be stable, balanced and have good and safe access. Each system is designed to purpose and a recommendation is made on the type of pump used and stirrer as part of the system.
Has your pond Danger warning signs?, Emergency exit?, rope ladder? Fence?
Is your pond FDE compliant, permeability tested?
Note department of labour new regulations are in place from May 2012