The floating leaves of a water lily or two depending on the size of your pond would cover the surface of the water and prevent too much algae. Algae is typical this time of year as the pond "wakes up." I think if you want blooming lilies or lotus you always have to fertilize, they will grow but not bloom without extra nutrients. You have other options to prevent algae like barley products. You can also make sure the surface of the pond has good coverage from plants limiting the sunlight that encourages algae. Good luck with it, algae can be a pain but it can be overcome.
