Hi all, we have recently moved into a house which has a large pond (approx 8ft long 5ft wide and 3 deep) - and we have found about 15 koi carp in it. Water level was very low (1 ft) we topped it up to 3ft with de-chlorinated water approx 4 months ago. Since then it has got more and more murky. We have taken advice from a local shop (replaced uv filter, stopped feeding fish, now running pump 24/7, new filter/sponge). At this time 2-3 weeks ago, we were advised that as pump had been off overnight all the bacteria would have died, and so should take opportunity to clean filter out (was full of sludge). We do not do any 'maintenance' on a weekly/monthly basis.

The water has started to get worse - large bubbles and foam on surface, and water is grey.

What can we do?! gf will be most upset if we come home to 15 floaters!

you can also post this in the pond part of this forum

Koi can be a real joy and become real attention seekers so it is worth a little effort.

Sorry but keeping them is not a fit and forget task, there is something to do in our pond at least weekly and sometimes more, unfortunately becuase of the state of yours this is probably a daily not weekly requirement, my pumps run 24/7 365 days a year .....

Are they still alive ??

You have an un cycled pond because the pump was off, so the fish are poisoning themselves in their own waste, not only that but turning the pump back on when it has been off for a long period is absolutely the wrong thing to do - you just pumped all manner of toxins into the pond (caused when the bacteria inthe filter die and the anaerobic bacteria take over producing such nasties as hydrogen sulphide. the first thing you do after a long term pump stop is clean out the filters thoroughly.

However since you didn't you know have all kinds of microbial and plant live thriving on the polution - hence the murk and the foam - yuch - the gray bloom is very likely an ammonia spike which tends to make water cloudy.

First thing - change 50% of the water for clean dechlorinated water
Second Thing - clean the filter
Third thing - Get some air in there - couple of big airstones to get the water circulating.
Fourth - test the water conditions using a good liquid test kit.

Keep changing the water daily until you have zero ammonia and zero nitrite and preferably less than 100ppm of Nitrate - if you wouldn't swim in it why should they.

Filter maintenance I'm sorry to say is a weekly task - especially in the summer months.

If you really want to do this right find a temporary home for the fish and relocate them (something like a large plastic bin that has been thoroughly cleaned) while you drain the pond and give it a thorough overhaul and refill, run an airstone in the temporary home and pay attention to temperature and ammonia levels, if either get to high change a little water.

This post has been edited by Jabba: Aug 28 2007, 09:33 PM