Midwest Pond and Koi Society - Q&A #96 - expanding an existing pond

Hi,
I am not sure if your e-mail is open to general questions or if it is just open to members, so if it is please disregard this e-mail.

I have a question about expanding my existing pond. I currently have a 4X6 pond that is about 18" deep with two bio filtration falls (one 16 inch bio fall and one home made up-filter made out of a 6 gallon office wastepaper basket and filter media) and about 1500 gallons of flow between my two pumps. Like most first time builders I built much too small. The problem is that my fish are now well established (4 5-6" comets, two 5" fantails and one 7" butterfly koi) and I would like to expand the pond on its existing site while keeping the fish alive.

!) I am not really comfortable with the idea of splicing liners so I would like to drain the current pond and expand the current hole to accommodate a 10x6 pond that varies in depth from about 18" to 24". Do I currently have enough water movement and filtration? (I can easily build a bigger up-filter with materials on hand)

2) I anticipate construction lasting about 3-4 days (I plan on building this one much better than the last). How can I keep my fish alive and healthy during their time outside of the pond?. I have thought of getting a large Rubbermaid container and hooking one of the pumps and filters to it for a temp solution. Will this work? Also, how can I avoid new pond syndrome?

3) I would like to add koi to my new pond. I think a maximum of 4 would suit me, but I am wondering about the pond volume. Will I overrun the capacity of my bio filters? I will be moving 1500 gallons in a 900 gallon pond, but I have read horror stories of the stress that koi cause on a smaller pond.

Thanks so much for your time and your response. Your site is perhaps the most helpful and informative site on the web for hobbyist ponders. Even though I am in the Mid-Atlantic, (Richmond, Virginia) I have found many tips and Q&A's that have been very useful.

Hi Whit,
Yep, you've run afoul of the Third Law of Ponding, alright, the one that says: "There's Never Enough Water". You are currently running 270 gallons, which is just about right for your goldfish, but which your koi will outgrow within the next two seasons or so, so your plan to rip out the current pond and expand is a good one.

Your interim plans for construction are good. A 150-gallon Rubbermaid horse trough from one of your local feed supply places (here in the midwest it's Farm 'n Fleet) filled with your pond water and filtered with your existing setup, augmented by a robust air pump and airstone will work just fine.

Let me encourage you not to limit yourself to the 890 gallons you are currently planning. If you want healthy, big koi, you'll need at least 4 feet of water for them to swim in, and you would not believe how fast the critters grow. Also remember that with 4 koi, you'll almost inevitably end up with fish of both sexes, and in the spring they will spawn. You will then have many more koi.

Deep water is to koi as a stair-stepper is to a human. The exercise they get in the transition from deep to shallow water helps with conformation and health. Going deep is also a wonderfully sneaky way of buying yourself more water in the same footprint. Another successful trick to enhance volume (and believe me when I say that larger ponds are easier to maintain, more temperature-stable and less liable to predation) is to build *up* about 18 inches with landscaping stone lined with rammed earth. That extra height not only gives you a comfortable place to sit around the edge of the pond so you can play with your fish, but also buys you an extra 600 - 700 gallons.

Ultimately, you'll need to set up your pumps, falls and filters so that you move the entire volume of your pond through your filters at least once an hour, and if you go deeper than 24 inches, you'll need to consider a bottom drain system for ease of maintenance and optimum water quality. If you are planning in this direction, I'd also suggest sticking with a bare liner bottom, since these designs tend to be self-cleaning and do not accumulate sludge the way rock-bottomed ponds tend to.

The best reason to go deep in your area is predation. My memories of the Richmond area are that it is still fairly open and rural, with a lot of wildlife. Its proximity to the Atlantic coast ensures the presence of cranes and egrets, as well as osprey and heron. The semi-rural nature of the area ensures the presence of raccoons. All of these critters (with the obvious exception of the osprey) are waders who look on shallow hobbyist ponds as their equivalent of McDonald's. Brightly colored fish are easily-spotted targets; your best defense is to go deep and steep, and leave the monsters no place to stand.

Look up the Mid-Atlantic Koi Club and join. It is full of nice people with extensive ponding experience in your area. They'll help you avoid mistakes.

Please feel free to use any of the information in our Articles and FAQs sections to help you plan. There's even a nice, simple, cheap design for a homemade self-aerating upflow filter in there if you look.

Happy planning and Ponding,