Pressurised filters

Hi everyone I recently moved into a property with a pre-existing pond in the garden and I’m looking for some setup advice. The current pond is a bit irregular – it’s about 200cm x 110cm on one side, 170cm x 110cm on the other, and 60cm deep (approx. 600-750 litres). It has gold fish in it and a small plastic waterfall cascade.The old setup is a Yamitsu/Kockney Koi box filter (I think), but the UV-C light has packed up and the pond is completely green with algae Since I have to replace the system anyway, I want to upgrade to something very powerful and efficient. Crucially, I would like to expand and enlarge this pond in the future with real waterfall. Because of this, I want to buy a pump and filter setup that has plenty of extra capacity to handle a much larger volume of water later on. I’d rather go too big than too small. Ease of cleaning is also a massive priority for me. What pumps, pressurised filters, or all-in-one systems would you recommend? I came across Oase Filters pumps, so I would like to hear opinions if anyone has them. Thanks in advance for your help! See less