The fish pond

Adventures in pond building.


After much negotiating with the wife, I built a pond in an unused corner of the back yard with the assurance that it “will be a thing of beauty forever.” There are still some complaints but only on the details.

With the donation of 100 square feet of pond liner from a friend, and lots of studying on how to do it in books and web sites, I started digging. The plan was to make something simple with the idea of changing it later if it doesn’t work out. It’s a simple 10’ X 6’ oval one foot deep with a center section two foot deep for a water lily if I want to add one later. Also I planned to add a veggie filter with the leftover pieces of liner.

Nice plan … but … as any general will tell you, “No Battle Plan Survives Contact With the Enemy.”

The first problem was an old guy, (me), with a bad back. For a fleeting moment, I thought of asking my wife dig the hole but somehow I knew that wasn’t going to work. I dug the hole but it cost me dearly. All my friends are in even worse shape so I would not dream of asking them.

After a suitable recovery period, I put the liner across the hole, put some cement blocks on them for weights, and slowly, slowly, filled it up. I thought I could avoid any wrinkles by doing it slow enough but I couldn’t. After the second time filling it, I declared it done, wrinkles and all. Actually, I think the wrinkles add a little interest to the pond. Maybe I can try it again next spring when I refill the pond. Maybe move the wrinkles around for a nicer effect. A friend with pond building experience tells me that it very hard for one person to fill a pond without wrinkles.


I used some of the wastewater complete with the fish poop from my indoor fish tanks to add bacteria to the pond. After the water warmed up in a few days, I added 7 adult red swordtails along with an unknown number of baby fish. Also I added handfuls of hornwort. (Ceratophyllum submersum).

That night, I had a visit from some raccoons for a fish dinner. Now I have three adult swordtails. I had planned to build a raccoon proof cover but didn’t get to it in the excitement of populating the pond. That night I used some plywood with cement blocks to hold them down which worked. The next morning there were many paw prints around the pond and some minor digging but no free lunches for them! Notice the paw prints on the lower middle of the picture.


I have since built some covers made with a wood frame and some plastic fencing stretched over it and that seems to work… so far. I only use the covers at night since they don’t exactly blend in with the décor. If later I get lazy, I can leave them on since they don’t block the light.

Two weeks later I noticed the hornwort died. The leaves turned to mud. I removed as much as was practical but the rest will become part of the décor. That’s a mystery. I noticed in a couple of web sites that copper will kill hornwort. It seems to be hearsay but it’s worth looking into. My inside tanks where the hornwort thrives uses water from a plastic pipe connected near the feed into the house while the water for the pond comes from a spigot on the other end of the house with 40 feet or more of copper pipe. It seems plausible but other explanations are also possible.

Just as an added item, I notice there is no green water! The pond gets about six or more hours of full sun every day which I expected to be a problem with single cell algae, but the water is still perfectly clear. This isn’t as good a thing as it sounds. I wonder if copper in the water is killing the algae. If it is copper, this can’t be good for the fish too so I will do a big water ASAP. Luckily, I have more hornwort so I can replenish it later when I think the water is copper free. Possibly this could be a copper indicator? In this case, if the water turns green I will be happy. I can cure green water if it bothers me and the fish won’t have a problem with a moderate amount of green water.

When I say “The water is clear” what I really mean is it isn’t cloudy. It is stained a tea color due to the occasional leaf falling in. I can see the fish fine, which is the main purpose.


DSCF0751You can see the chair and the makeshift tables next to the pool. It makes a nice place to hang out in the morning. You would think there would be swarms of mosquitos near the pool but it is mostly mosquito free. The fish must be taking care of that problem.

DSCF0754 DSCF0756

It still is a work in progress as you can see from the pictures. The trench you see is a veggie filter that I am making. I don’t really have enough of a bio load to support marsh plants so part of the filter will need some garden soil. I will also be making an open section in the middle to raise shrimp in, (not the eating kind but cherry shrimp). I plan to construct a bridge over the filter open section to hide the permanent raccoon cover which will probably be needed.

Well… it’s now the Labor day weekend, (2014), and I have been pretty good about putting the raccoon cover on the pond at night. I did miss the cover one time in early August but I didn’t notice any fish missing. The water was stirred up and the plant pots overturned making a mess with all the dirt from the pots clouding up the water..

After that time the water started to turn green and it has been that way since then. I assume the cause was all the dirt that the raccoons released in the water. It’s odd, however, that when I tested the water just after that raccoon thing, I didn’t measure any nitrate or nitrite in the water. The duckweed covers about 30% of the pond but the green water persists. Next year I will investigate having more floating plants.

I have been looking at the water temperature every morning and in the afternoon. In mid August after a warm week it is 72 degrees F at the deepest part and 80 degrees F in the afternoon. That’s about an 8 degree temperature swing every day. I will have to see if I can make the pond deeper. It calculates to be 120 gallons, (if I can believe my math.) If I remove the 12″ shelves around the sides I probably can make it about 300 gallons.

I wonder how long I can leave the fish outside? It is now the end of August and the morning water temperature is 68 degrees. The morning air temperature was 47 degrees but when I measured the water it had gone up to 58 degrees. I did a count of the fish I could see and there are about 30 1/2 size fish and out of the original fish I can only see 4. The water is green so I’m probably missing most of them. I better start making room inside for them.

This fall when the water is drained, I have some improvements planned. As I mentioned above, I will make the pond deeper to minimize the daily temperature swings. Also I had installed a solar powered water pump to keep the water stirred up and it actually worked. (Not everything is a bad idea). I plan to use something like this to make a waterfall. I’m not concerned that it will be off every night since I don’t heavily stock the pond with fish. It’s really just to make me happy. As for the veggie filter I planed, maybe I will incorporate it into the design.


One major problem I hadn’t anticipated was running air to the pond. Originally I had planned to run an airline out to the pond since I prefer to place the air pump inside the house out of the weather. I forgot that the pump should be above the water level of the pond water. The four possible solutions are;

(A) Put the pump in a higher part of the house. (Too noisy!)

(B) Put an anti siphon valve in the airline. (Not 100% reliable.)

(C) Don’t use air. It worked this summer fine and it may be what I do depending how lazy I get. However, this was a cool summer which I can’t always count on.

(D) Lower the pond. This is the best permanent solution and probably what I should do. This points out that you need to plan before you dig!

I will have to do some digging anyway since I noticed some problems when I partly drained the pond to catch the fish. I needed to make a steeper slope toward the deep end of the pond so fish aren’t trapped in the depressions when I drain it. The good part is with a small deep hole in the pond, the leaves, and other stuff concentrates in the hole making cleanout much easier.


The pond is much better than last year. I had dug it out deeper and removed the shelves on the side thus increasing the volume to a little more than 300 gallons. Also it is as deep as the liner will allow at 18″.

I also added a filtration system with a vegi filter. It is a submerged pump, (Quiet One 400.) and a buried 5 gallon plastic pail with a fibrtgall mat to remove solids.

In June, I put in three, 1″ goldfish and a little later in July I put in around 50 baby guppies for an experiment to see if it is practical to use the pond as a grow-out tank.


One thought on “The fish pond”

  1. 9/7/2014
    I had made some room for the pond fish inside and removed the fish I could catch into the inside tanks. I will have to remember next year to set aside more time for this.

    The fish are outstanding. They started as simple swordtails and platies that I got from a friend and ended up as fish you would be proud to show at a fish club. I don’t know what it is but the colors were much more vivid as compared to my memory of how they looked when the were put into the pond. Also I now have a lot of 1/2 grown fish along with uncountable numbers of small fish.

    The experiment with potted Cryptocoryne and sword plants wasn’t a success. The algae completely covered the plants, pot and all. I put them in a tank with some catfish and they seem to like the algae so it wasn’t a complete failure. As I look at them now, they are mostly algae free and seemed to have been growing although I expected more growth. I won’t do that next year.

    Today I will catch the remainder of the fish and make some plans for next year’s pond.


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