Fish in Garden pond

[strain]

My pond is very green with algae - there are approx 10-11 fish in it and over the past few weeks one fish died and floated to the top. There is a mixture of koi, carp and large goldfish. I have been on holiday and my family where feeding them however i have only seen one of the goldfish since returning after 3 weeks - there is a net over the pond which has not been broken. Different people have told me they are probably at the bottom eating the algae and I am unlikly to see them but I am still worried they are all dead. I inherited these fish when a friend of a freind emigrated to Oz. The pond does not have a pump in it and was orginally put in to attract the frogs in my garden. Of the three weeks I was away the first week was warm and the second two very wet. I live in Northern Ireland. Any small amounts of feed I am putting into the pond appear to be eaten. However before I went away if I started talking at the side the fish all came up to the surface. This is not happening anymore. I have bought an algae clear and a friend has suggested replacing some of the pond water which I was planning on doing this weekend. I have also used a net in the pond but did not seem to disturb anything. These fish survied a cold winter when the pond was completely frozen. Any ideas or suggestions will be most welcome.

[ipek]

First of all, I would not bother to replace any water - in fact it is better to leave the water that is currently there. It has matured and replacing it (particularly with tap water) only adds unnecessary chemicals - topping up when the pond loses water in summer is OK as it usually not a great volume.

Secondly, if you can, add a pump - nothing too vicious or large, just enough to keep the water moving. This will clear the water of algae faster than anything else and Koi like clear water. It also aerates the water for the fish.

Fish do tend to disappear to the bottom and in the plants - be patient for a while and I'm sure you will find they are fine. The net should keep off marauding cats as well as herons, but there is always the possiblity that they've been hunting.

[hammerman]

First of all....i WOULD do a water change. I do a 10% water change on my 3,000 gallon koi pond every month....with tap water. This helps dilute the chemicals that filters can't remove such as phosphates and nitrates.

Secondly, a pump will do NOTHING unless it is linked to a filter and a UV sterilizer. The filter will remove fish waste and toxins such as nitrite and ammonia which are a product of fish waste and the UV will clear green water. You will need to revert to chemicals to clear blanket weed (cloverleaf do a very good blanket weed killer which i use in both my koi ponds)

Hope this helps

[strain]

Thanks you for your help - i did change some of the water and found two fish in the pond dead behind a couple of stone - since taking them out the rest of the fish seem much happier and have all come up to the surface again - they dont appear to be eating yet but perhaps there is enough algae in the water - there is no blanket weed or weeds in the water but I added the algae granules which should clear the water within 2-4 weeks