Hi all..I hope thereare some enthusiasts on here that can help me with my desperate quest!! Ive just brough a new house and there is a pond in there with (somewhere) fish!! Its very green and murky..you can only plug in the "what we think is a pump" via a lead into the house so this can only be done in good weather! Where do i start? Do i strip it down and start again or will it mess up the balance?

I dont even know what fish are in there! there are two leads going to the pond Which is housed in a plastic box!! (not safe i know this will be addressed as soon as poss) but in the mean time, when you plug it in (via a lead in the house through a window!!)the water spurts up through a tube running from what i beleive to be a pump which is located out of the water at the side, i dont even know if there is filtration..the wate is pure green and the bottom is sludgY. (i keep tropical fish so i understand some things)

Any ideas where i start? Thanks in advance.