Thoughts on building a pond

Hi Eric,
In my previous home we had a large goldfish pond that I put in, and of course I got the hankering after that for Koi, but did not purchase any for my inadequate pond.
10 years ago we moved into our present home, and immediatly I started digging my Koi pond. But as a police officer and working shifts, it was taking time, and during that time we had an extension put on the house, and then I purchased a conservatory which my father in law helped me put up. Guess where all the earth from both footings went. You've got it, in the hole I had already dug. So when that was all finished I got back to the pond, by now 5 years had passed. Of course in that 5 yrs I have done a lot of reading on Koi pond construction and my views changed to what I had planned. The hole was being re-dug and got larger and larger.
This was all being dug by hand to keep the costs down in heavy clay, placed into a wheelbarrow, taken round to the front of the house and placed in a small box trailer that my brother in law gave me and taken to a farmer friends field nearby and dumped after leveling it on his field.
Over the next couple of years the hole got deeper, the rains came and the sides collapsed, so the pond got bigger. In the end I decided that the pond would be 19' x 10.5' x 6' deep, kidney shaped, making it just over 7000 gallons. Some while ago I found your site whilst at work, as we are allowed to surf the net during our grub break and not having a computer at home, I printed all your pages re pond construction on the 24/05/02, which I use as my bible.
The hole was originally 7' deep, but now 6' as I have placed two aerated bottom drains in the base along with reinforcing mesh in the concrete base. I am now waiting for better weather to start building the walls which are hollow block with reinforcing rods inside continuing up from the base. The pond will be level with the ground, no raised wall, as I want it to complete the garden and not stick out like most I see.
I have deliberately not hurried this project, I want it to be right, or as right as it can be the first and only time. I want the best that can be purchased, even if it means putting it back a year in order to save the money. In order to get to this stage I have since joined a local Koi club, which I should have done years ago, but most of my praise goes to this fantastic, excellent site, which has informed and helped me out so much. I can clearly say it is the best site on the net, and I have looked at quite a few. You cover every point in detail, the diagrams speak for themselves, not like the many books that I have purchased over the years that leave you to guess at so much. I have also written to Koi magazines, and although they have published my letters and answered me, they still do not fully answer the question.
The updated version of your site is even better, and as I still have my bible, I can see that you have even put more information on there, which assists me greatly. I am at the stage where I have got to decide what sort of returns I am going to put in the wall, I am going along the lines of TPR's.
I should at this stage explain my proposed set up. The two bottom drains will each go to its own seperate filter system. The first bay being a vortex, via a 4" pipe which will have ball valve fitted, then into a four bay filter system which I already have. The last bay will have a pump which will put it through a UV and back into the pond. the other vortex will feed a different type of filter set up, possibly another 2 vortex chambers converted to filter bays and then back into the pond. Either pump will go via either 2" or 1.5" pipework, again fitted with ball valves, into a three return set up, a deep return, a mid water return, and then one just below the surface. I am not going to bother with venturis as I dont want to restrict the flow and also the aerated bottom drains will fulfil that purpose better than the venturis I think. Do you think I am doing it right in this way, ie three returns in this fashion, if so what power should the pump be, I have yet to sit down and work that out as yet, but I am looking at the Oase 15000 for both returns.
I will have a skimmer fitted which will feed a header pond which will incorporate a vegatable filter, returning via two waterfalls. But thats a long way to go as yet. The pond has yet to be fibreglassed, and thats going to cost an arm and a leg, but it will be worth it.
I am still battling with the idea of benching the base of the pond, some say you should as it helps clear the sediment, but some say you should not bother, certainly not in my set up, and that a benched base does not allow Koi to overwinter on the base easily because of the slope. I have yet to make a decision.
Again I just wanted to thank you for such a well informed and helpful site, and anyone who has problems or wanting information I always tell them to look at your site.
Regards Chris

Hi Chris,
Thanks for taking the time to send this interesting letter, and I will add it to the Letters page.

I think that with a pond of 6,000 gallons or more then having a twin filter system is a good solution.

The question of venturi's has been discussed here recently. I would still like to have both, but it is something that you can always add later. Some of the venturi's you can buy now, which are at the cheaper end of the market, are quite efficient even with a low output pump.
If you are going along the line of TPR's then I suggest you read up what we have written on this website.
As I have said before I do not discuss makes of pumps or filters as this is best discussed with a dealer who can advise what is available in your area, and you can go back to him if it does not perform as expected.

The question of benching is something that can be argued all night without coming to an answer. In the end it is up to you to decide. I personally prefer benching, but if you have blanket weed on the base it will prevent the sediment from moving. The slope is quite shallow and I don't believe stops the fish from resting in the winter as nearly every pond I know of in this area is benched.
Eric