it takes the pond water a long time to age.dont clean the sides of the pond,that is the good stuff that will help clear your pond.a good skimmer is also helpful,keep your filter pads clean and a weekly water change of about 10% to 15% will also help

The brown residue is probably stirred up soil, or koi fish waste. Koi fish are considered "destructive" to plants and have large, powerful fins which can easily stir up soil. They also release ammonia, nitrates, nitrites etc. (waste product) into the water. This will promote plant and algae growth. The barely straw should keep the water relatively clear, but I would suggest a UV pump/filter if you do not own one yet. There is really no need for a weekly water change because evaporation will take place and you can just add water every once in a while. Even though the developing algae rimming your pond may seem ugly, I wouldn't remove it. This algae is beneficial to fish by absorbing excess ammonia and providing food for the koi and smaller fish. Just for heads up, I wouldn't add fish just yet. People usually wait a week or so to insure that beneficial bacteria and other mutualistic microorganisms have developed and circulation is properly working. Since your pond is quite large, I personally, would add mosquito fish into the pond to insure that mosquitoes do not spawn larvae. Well I hope this information will help you and good luck on your new ecosystem!

Cat

Couple of questions - does the water have a brownish cast, a greenish cast or just a cloudy look. Each of these conditions can be caused by different things and need different treatments. The stuff collecting on the sides (and probably bottom) of your pond is good stuff so don't worry about it. It is probably beneficial bacteria starting to colonize there and could be some string algae starting to grow. Both are good things to have. Don't be confused by algae growing in your pond. There are basically two kinds that will grow, string algae and free or single cell. string algae is what will grow on the surfaces, and in places where your fish can't get to it will grow in long strands like hair (some call it hair algae). The fish will graze on this kind and keep it short where they can reach it. It's a good kind to have in your pond as it will digest pond nutrients just like your plants. Single cell or free algae is the kind that floats in your water and makes it look green and if not controlled will turn your water to pea soup. The barley straw will mostly work to control the string algae. The way it works is as it decays it produces hydrogen peroxide and other chemicals that kill the algae. In fact if you were to just pour some hydrogen peroxide onto the string algae that may be growing in your waterfall it will kill it immediately. The best way to control free algae is with a UV light sized according to your pond.

A little about pond chemistry. Fish produce ammonia which is deadly to them. Beneficial bacteria that grow in your pond and in your bio filter convert that ammonia to NitRItes, also deadly to your fish. Further bacterial activity will in your filters and pond surfaces will convert the nitRItes to nitRAtes. Nitrates are not harmful to your fish unless at high levels.

I must disagree with CatCatBar on changing water. If you only replace evaporation then the nitrate level will continue to increase as you are not taking any of the nitrate saturated water out of the pond. Over time the nitrates will increase to a troubling amount and you may get sick or dying fish. To prevent this you should REPLACE 10% of your water every week or two with aged water or use a Dechlorinator.

Keep a close eye on your pond for signs of troubled fish. I say this because your pond is new and the beneficial bacteria haven't had sufficient time to colonize yet. It could take as much as 6 to 8 weeks. Of course this all depends on how many and what size fish you have put into the pond. A small number of small fish in your size pond will not be a problem. However, if you added some larger fish or a lot of them then you could create a situation where the bacteria can't keep up with the ammonia production and your fish could get ammonia poisoning.

Finally, your koi and goldfish will do a good job of eating most everything in your pond, including your plants, floating plant roots, insects, tadpoles, eggs and larvae (including mosquito larvae).

Hope this helps and good luck. I hope your pond will give you as much enjoyment as my 3 do.

Normally a pond has a cycling period that allows for the water to become a safe environment for the fish. A lot of the times people will put in a pond, fill it and put in their fish all of them at once. This creates issues with water quality and cause spikes that may kill the fish. We all want a clear healthy pond and this takes time and patience. If you like follow the link and read about water quality and koi. It just may help

Here is a link that might be useful: koi club