Sorry been trying to respond to this all day,typing paragraphs and the damn app keeps force closing before it sends. Anyway 100000000% on a UV sterilizer for that size pond a 25 watt will be fine not just for algae but overall health,types of carp tend to be heavy on aeromonas and psuedomonas among other things. Personally I'd recommend an Aqua Ultraviolet no wiper and or an Emperor Aquatics. Get yourself at least a barrel filter better would be a sand filter,bead or bio filter. Cheap end but effective is a Tetra Pf filter(atleast the 2) the pressurized is better but like 5 times the $, a little more advanced is the aqua Ultraviolet bead filter Ultima II 1000 would be fine. There are others too but ideally you want that style I just mentioned those to give examples of what I personally have used for a bunch of ponds and I know work. Don't get the combo filter and UV, other than the effectiveness if a pump breaks or the unit now your left with nothing running as opposed to at least 1 of the 2 running.The combo is better than not having them though! Without a uv and getting sunlight the pond will be pea soup unless your insanely planted. No need to get rid of the comets unless you don't like them,they do breed prolifically usually bur if you have kids in the family they'll probably love it. You can absoulety, competely clean the pond and keep those fish at the same time. Is it a plastic pre formed or rubbermaid (firestone) liner? If it's not a concrete and or heavy rubbermaid preformed be careful when scrubbing, depending on natural location you can easily put too much pressure and possibly puncture the pond with rock in the ground. Again depends on what and if anything is laid below the pond but better safe then sorry. You should completely scrub,drain and fill the pond it will take multiple drain and fills and probably a lot of scrubbing. I always use algae pads, scrub brushes, I'd highly suggest having multiple tools to scrub and a few different styles,between wearing out,changing position and fitting in certain areas you'll be happy you did. In general unless something major happens,heavy rain,crazy parties lol you only change water twice a season, once to open and once to close so it makes sense to start out the season spotless. Be sure to get all the leaves and stuff out before it warms up,that stuff becomes a mess when it breaks down and that's when people normally loose fish. The equipment between pumps,filter and Uv going brand new going to be $1k plus but other than normal maintenance on the stuff if you take care of it it'll last as long as the pond does. Also I'm a huge fan of Supreme mag drive pumps for the pond,take a beating and last forever also can get the extra long plug. Feel free to pm me for details,depending when your looking to do it I'd come by and help for sure,miss the pond days! Get that pond brand new and sparkling in 1 day.
