Even though we have been keeping koi carp for about ten years, I decided to upgrade my filter on my pond at the end of Summer 1996.
My original filter consisted of three large tanks and the filter medium was Canterbury Spar, this set up seemed to work alright but the problem was that I was pumping the water up to the tanks which were above ground level and then the filtered water was returned to the pond via a one inch pipe by gravity. The main problem was that the turn over of the water through the filters was dismal, as my pond is 7,500 galls I very much doubt if we were turning the pond over every two days. Apart from this I must admit that my water quality seemed to be O.K. and the fish did not seem to suffer. I put that down to the large capacity of the pond compared to the stocking levels of the fish. Well after a few pond visits I had picked up a few great ideas from the set ups I had seen, and at the end of last September we commenced work on the new filter system. We decided to convert my original pond which was about 1.000 galls into the filter, and of course then the digging commenced. we installed a large vortex which was fed by a 4" pipe by gravity and then on to the filter chambers, also another 4" pipe that fed directly into the filter chamber. the reasoning behind this was to use this as a mid water delivery to the filter for the winter months. A third 4" pipe was connected directly to the standpipe chamber to be flushed directly to drains as waste. Well by the early part of last spring the system was compete (apart from putting the garden back together that looked like a bomb had hit it) and it all seemed to be working satisfactory. Every thing in the garden should have been rosy but not so. Something was lacking - bottom drains. Because my pond was made with a butyl liner I had come to the decision that to install bottom drains at this time would be an impossible feat,and so I was left with my two 4" feeds to the filter and my 4" drain sticking through the end of the pond with a bend on the end and a pipe reaching to the bottom of the pond. Taking into account that my pond is twenty four feet long this in my eyes was not the ideal situation. All through the summer my new filter worked well and did have a significant affect on the well being of my fish and the water conditions, but we were still not satisfied and would not be until we had bottom drains. After thinking about the feasibility of cutting the liner and installing the bottom drains over and over again, and not to mention the times I had woken up in the middle of the night screaming, I came to the decision that for the sake of every ones sanity I must attempt the impossible, successful or not, or end up in a padded cell muttering bottom drains under my breath until the end of my days. What follows is a brief account of what happened when we undertook this task. MD

My next problem was how do join the butyl liner back together after it had been cut. I must admit that the very thought of cutting the liner open sent shivers down my spine as it does not seem to be the actions of a sane person to take a Stanley knife to a perfectly good liner and slash it open. Then I remembered the company I had originally purchased the liner from and I rang them.

I must admit that the staff at Midland Butyl were very helpful and they suggested that the best way to join the liner back together was to use a 2" ribbon strip and to purchase some new butyl liner to put on the top. This is what I did and waited expectantly for the post to arrive. I also purchased the 4" pipe for the drains and all the building materials I needed to compete the job.

Day One - Wednesday.
When I finished work on the wednesday evening I set up the show vats on the patio making sure that I put old carpets under them to protect them from any sharp edges that may have been on the ground.

Day Two - Thursday.
When I came home I proceeded to pump water from the pond into the show vats, when they were filled I proceeded to catch the fish and put them in the vats. But then disaster struck as my net snapped, and the only way I could catch the fish was to join them in the pond which by this time still had about two feet of water in there. Eventually as darkness fell we had managed to catch all the fish, and by this time I was soaked to the skin and freezing cold and glad to jump in a nice hot shower. Something else that is worth bearing in mind is something that did not occur to me at the time, some of the fish in the vats started to jump and we quickly had to fit makeshift covers over the vats. I'm glad that the fish started jumping when we were still out in the garden, because I am convinced that if we did not cover the vats half the fish would have been all over the patio in the morning.

Day Three - Friday.
As soon as the sun rose I jumped out of bed started to clean the pond out. I have a high pressure washer which is a marvellous tool at times like this. When the pond was clean I dried it out as best I could, and then I marked out where the 4" pipes had to go, and then I was just about to cut the liner in several places then a thought struck me. What was the point in cutting narrow slits in the liner as I would have to struggle to excavate the earth from them, why not cut it right open and peel it right back to give myself plenty of room to work when I was digging and laying the pipe work.

So that is what I did I cut the liner right up the middle of the pond and then at the end I cut a “Y” at 45 degrees as far as I needed to go and then I opened it up like a pathologist would open up a chest during an autopsy. Once the liner was pulled back out of the way, I had plenty of room to dig out the trenches for the 4" pipe work, which was quite hard work because at this depth we are down to the old river bed which consists of a small amount of clay and a large amounts of pebbles. In a surprisingly short time it was completed and I then installed the pipe work and the bottom drains,and proceeded to concrete them into position and by about 5:00 p.m. it was completed. We then retired to the pub for a well earned couple of beers.