Rendering a Koi pond

[siko]

I consider myself a reasonable DIY'er but would like to get a straight answer on the following question.I have left over from the building of the pond (which is 7ftx7ftx6ft deep using Dense concrete blocks) about 1/3 of a jumbo bag of building sand. Can i use this for the render using it in a 3 sand to 1 cement ratio? I will be adding fibres to the render and the final finish will be fibreglass. I am getting conflicting answers from websites, some saying use building sand and some saying use sharp sand. Thanks in advance for your time in replying.

 

[Jasonb]

The guy who rendered my pond used a mix of fine sharp and building sand around 3:1 as it made the mix easier to work. You may get away with just building sand on the base but it tends to fall off the walls.

Jason

 

[siko]

Thanks for your reply, that was my kinda thought on it.