Greg gave the options on methods of liming. First you need to check your alkalinity to be sure you need to lime(or are close to needing to) if you haven't done so. A soil analysis of the dirt from your pond bottom is also a good idea to see what you are working with. It is possible to add lime and have great alka. but be missing one of the other necessary elements (nutrients) to have a sucessful fert. program. You may have done this already and if so then you are ahead of the curve. Good luck. ewest