Thanks for the reply
Well, I wanted it to be planted with Valls,cabomba,crypts etc. Hence, I wanted a filter so people can actually see them. Also, I an not interested kois, coz they ll probably die of heat or get eaten by birds and they are not native to India. This pond is neighboring one of the largest national parks of Asia, and one of the most well preserved too. A lot of homework will have to be done before adding any fish, in case it escapes. Right now I am thinking of adding small shoaling natives, in huge numbers.
And yea, even I am thinking now do I really need a lot of filteration. The pond is quite big and can easily start its ecosystem. I think I should first make it hold water, see how it goes. If it clears up I ll let go of the filter. Else I ll do something.
Do you think $12/meter is a good price for butyl liner?