Galvanized Stock Tank Fish Pond

Stock tanks have been used for keeping fish for a lot of years. In the early days of the West, galvanized stock tanks were placed next to windmills and were used to provide water for cattle and horses. These stock tanks are still being used on ranches today. Some of these old stock tanks are over 50 years old and have been kicked and abused by livestock but are still holding water. The ranchers just mend them and keep using them.

I ran into a very old stock tank at a rental store a few years back.  It had large dents and some holes in it.  It was a 6-foot diameter galvanized stock tank and looked very old.  The store offered it to me for $25, including delivery since they wanted to get rid of it.  I hammered out the dents and patched it up and used it for many years as a raised pond.

My wife’s grandmother, when in her 90s, liked to talk about her dad raising goldfish in stock tanks when she was a little girl on a Kansas farm.

Many people are unaware that stock tanks make excellent ponds for water gardening and keeping fish. This is a shame since stock tanks are an excellent alternative to plastic liners, which is what most ornamental ponds are made from today.

Galvanized Stock Tanks and Poly Stock Tanks

Stock tanks come as galvanized stock tanks and poly stock tanks.  The poly stock tanks are newer and becoming widely accepted now for use by ranchers and farms.  However, many farmers and ranchers still prefer metal tanks.  Both should work well for ponds.  I have only used galvanized stock tanks though since when I got into ponds, only that type was available. If I decide to put in another pond, I may consider buying a poly type.

Galvanized Stock Tank Prices

I checked with a local farm and ranch supply store and found out that galvanized and poly stock tanks are about the same price.  A 10 ft diameter stock tank that is 2 ft deep and holds 1200 gallons sells for about $400 as of February 2012.  The 8 ft diameter sells for about $350.  There was also a delivery fee of $75, which is necessary for most people.  The poly stocks come in either blue or gray.  The galvanized tanks can be either left plain on the outside or painted.  Prices will vary from state to state.

Galvanized stock tanks are made of galvanized sheet metal, which has many advantages over pond liners. It is strong, durable, and flexible enough to expand when ice covers the pond.  Since the sheet metal is galvanized with zinc, it protects the metal from rusting. When new, the galvanized metal surface is a shiny silver color, which changes to dark dull color as it reacts with the chemicals in the water.

Aging Galvanized Metal Tank

Does galvanized metal hurt fish? fish seem to do better in galvanized stock tanks that have been aged for a while. One of the best methods to age the stock tank is to buy it in the fall and let it set full of water until Spring when it will be safe for fish.

Of course, it could also be purchased in the summer and used as a swimming pool for the kids until it aged sufficiently for fish.  All pond tanks, regardless of how they are made, should be allowed to season at least a month before adding fish.  Plants can be added immediately though and will help season the pond.

What is the best fish you can add in a stock tank?

It is also a good idea to never add expensive fish to a new pond. Start out with feeder goldfish and see how they do before considering anything like expensive Koi. Just a word about Koi.  They tend to grow fast and get large so they are not really ideal for smaller ponds.  If your main interest is water gardening, it is best to stick with goldfish and plants, or other coldwater fish since Koi can be destructive to pond plants.

What Is the Ideal Depth for Water Lilies and Fish Pond?

Stock tanks are 2 foot deep, which is an ideal depth for water lilies and fish.  A lot of pond owners on the front range of Colorado think that a depth of 3 to 4 feet is necessary to protect fish from freezing. Based on my own experience, I have rarely seen the surface freeze down more than 5 to 6 inches if the tank is buried.  However, if the stock tank is used as a raised pond, it should have a stock tank heater, or it could freeze totally.  If a stock tank heater can’t be used, the stock tank should be drained and left empty for the winter.

Actually it’s the carbon dioxide that builds up under the ice during extended cold spells with subzero air temperatures that kills fish, not the depth of the pond. Koi seem to be more sensitive to this problem than goldfish.  When I had Koi, I always kept a stock tank heater in the pond.  Since I now only have goldfish, I don’t worry about keeping an opening in the ice since goldfish are hardier than Koi.

Galvanized Stock Tank Sizes

A 6-foot diameter stock tank makes a nice home for a half a dozen middle-sized koi or goldfish since it holds about 700 gallons of water and has about 50 square feet of the surface. It is also large enough for 3 or 4 water lilies, depending on the varieties.

A 10-foot diameter stock tank holds about 1200 gallons and has about 78 square feet of surface area. These stock tanks are made either a little larger or a little smaller, so they can be shipped and stored easier.  So a 10 ft diameter tank will not be exactly that size.

This size tank is large enough for 5 water lilies and about 10 small Koi or goldfish.  Of course, more fish could be added, but I believe that a lighter stocking produces healthier fish.  Keep in mind that Koi can get quite large so it can outgrow a pond.  Goldfish do not get very large, but they tend to produce a lot of offspring so can also overrun a pond.

Stock tank prices appear at first glance to be a little higher than plastic liners.  However, since other materials such as rock to line the edges of the pond are not needed, the final cost of the pond may be less than using a plastic liner.  You can find stock tanks at farm and ranch supply stores.  Make sure you have it delivered if it is a larger one.

Stock tanks can be used as raised pools or buried to their rim and used as regular ponds.  When you first get the stock tank, set it in a level spot and fill it with water. Then carefully check for leaks which may have developed due to flexing of the metal during delivery. Mark the spots where the leaks are and open the drain on the lower side of the tank and drain out the water.  Patch the leak with Silicone and allow drying the recommended time before refilling.  They don’t normally start leaking again after being put into their permanent location.

Raised Ponds and In-Ground Pond

Raised ponds have a lot of advantages that are not immediately apparent.  Based on my experience with above-ground stock tanks, raised ponds are much easier to take care of.  It would also be better for a handicapped person or an older person since they wouldn’t have to get down on the ground.

The fish and water lilies are closer to a raised pond, so they are easier to see without having to bend over.  To do maintenance or cleaning is easy since the pond is up high. Of course, the biggest advantage is that you don’t have to dig a hole for the pond.  Once I put a 10-foot high windmill by my 10-foot tank, which enhanced its farm look.  However, the possibilities are endless on how to decorate it.

To use a stock tank as a raised pool all that is required is to have the delivery man put the tank on the lawn where you want it.  Then add a little water to see if the bottom is level.  If it is not, add some bricks or lumber to raise the low spot.  When it is level, fill it with water and, except for the aging process, it is ready for the fish.

Aging is not necessary for plants though and can be put in immediate.  Even liners ponds should be allowed to age and stabilize before adding fish.  Always start out with cheaper fish since you will lose some. Stock tanks are not real heavy since they are made of sheet metal, so one person can normally move it around when empty by lifting one side slightly and dragging it into position.

The best way to makes sure it is level is to fill it about 1/2 inch deep and raise any side that is not high enough.  When the tank appears to be level, go ahead and fill it the rest of the way to the top.  If it is not level when full, open the drain near the bottom to drain the water out and re-level the tank.

If the stock tank is to be used as a regular pond, place the stock tank on the lawn where you want the pond.  Cut a circle in the lawn at least 4 foot wider than the tank, which will give you two-foot on each side in case you need to get down in the hole to move it around.  Move the tank out of the way and start digging the hole.  Make the hole only deep enough to cover the tank up to 2 to 4 inches of the top of the stock tank so that the rim of the tank will be above the level ground when in place.  That will prevent rain water from washing dirt into the pond.

Use a level and make sure the bottom of the hole is level.  If the soil is sandy, you can also fill the hole about an inch with water and dig the shallow areas deeper until the water is an inch deep all over the bottom of the hole, which is the way I do it.  Next, slide the tank into the hole and refill with water.  Check again to see if the water is approximately level all the way around.  If not, pump the water out and insert dirt under the low areas.  It is best to have two or three people to help you get the tank in the hole.

Now fill in the hole around the sides of the tank. Raise the dirt level almost up to the top rim then take some of the grass that was removed when the hole was dug and place all around the rim. Grass growing right up to the rim looks really nice and is soft to kneel on to watch the fish or to do pond maintenance.  Of course, you could also use flat rocks around the rim in lieu of the grass, which is an interesting effect.

One of the best features of the stock tank is now realized. Since the tank has a rigid rim, people can stand right on the edge of the pond without falling in or the sides of the pond caving in. Since the rim is slightly raised, it’s easy to get close to view the fish and the water lilies.  My grandchildren like to lie down on the grass and hang over the side and watch the fish and feed them food from their fingers.

If you want to make the owner of a liner pond nervous, step on one of the rocks on the side of the pond.  The sides are not strong or rigid like a stock tank so could cave it.  I remember going to a pond tour one time and the pond owner was constantly telling people not to get too close to the pond since it might cave it.  When I was on the pond tour, I never worried about people getting too close to the edge of the ponds though.

I leave water in the ponds all year and the water lilies and the plants survive the winter well.

How to Grow Water Lilies in a Container?

Water lilies can be grown in a container on the bottom of the stock tank. Fill the container full of garden soil and top off with gravel after planting the water lily.  If shallow water plants are grown, use small inexpensive outdoor plastic tables to set the container on. Fill the container with dirt and top off with gravel to prevent fish from digging in them.  If the tables aren’t tall enough, raise the container with bricks.  Koi like to hide directly under the tables with only their noses exposed.  These inexpensive tables can be bought from Wal-Mart and other similar stores.

painting galvanized stock tank

Galvanized stock tanks, used as raised ponds, are not very attractive so something should be done to improve their appearance.  The easiest thing is just to paint them with metallic paint.  I used a spray can accomplish it and usually, it doesn’t take too many cans. Only paint the outside of the tank. The color can be your preference, but I like blue or brown.

One of my galvanized stock tanks, which has been painted with blue metallic paint is being shown on this book cover. I also have used wood slates on the outside of the stock tank, and it looked very sophisticated.  What I did was buy 6-inch cedar boards and cut them to 24 inches long.  Then I rented a metal strapping tool and put a couple of metal bands on the outside of the tank to hold the boards in place.  It came out looking very good and the boards never did fall off.

How Long Should Stock Tanks Last?

I have some that I have had over 25 years.  I have patched them though when I got small leaks.  Swamp cooler tar works very well to fix stock tank leaks.  However, the tank needs to be drained, dry, and clean.  Just apply the tar with a brush.  It dries in a couple of hours and can be refilled after a few hours.  Follow the instructions on the can about swamp coolers.

I have had a lot of stock tanks over the 30 years of owning ponds.  Occasionally I have thought about trying a liner pond, but after talking to ponders in my pond club, I decided against it since I just didn’t have as many problems as they did.  Disease has never been a real problem like it was with many of their ponds.

I was talking to a Professor at Colorado State University.  He was presenting a class for Master Gardeners, which I was attending.  After the class, I mentioned to him about not having many problems with diseases in my stock tank ponds.  He was their expert on plant diseases and said that the zinc probably protected the fish.  He said zinc was used to prevent diseases on plants in the early days.

String Algae in Pond

Another problem that I haven’t had is a lot of trouble with string algae, which plagues most ponds.  I wonder if the algae don’t like the zinc.  However, I haven’t noticed a lot of difference with green water caused by algae.  It just takes a while to balance out.  Of course, a good biofilter can reduce this time significantly.

These are the stock tank ponds that I have had. I had one raised pond and four buried stock tanks when I lived in Colorado Springs.  These tanks were 8 to 10 ft in diameter.  I also ran a small business selling water lilies and pond plants, using these stock tank ponds.

When my wife and I moved to Pueblo, Co, I put in three buried stocks tanks to be used for ponds. The raised pond from our former residence was moved to our new house.

I don’t use rock by any of my buried ponds, but grow lawn right up to the rim of the stock tank.  It is easy to mow the grass next to the pond.  A person can also sit right next to the pond and let the fish eat from your fingers.  Adults and kids really enjoy this experience.

It is not unusual for people to use stock tanks for ponds and many people that have them love them.  They are also not concerned about their dogs getting in the water and tearing a hole in the liner. 

Should I Put Gravel in the Bottom of My Pond?

People wonder if gravel should be added to the bottom of the stock tank to make it look more natural.  I don’t recommend it since it tends to accumulate debris and is difficult to keep clean, so it is best to just leave it out.  The bottom will soon get covered in algae so it will lose its bare look.

What if you lose interest in having a pond or may no longer be in good enough physical condition to take care of it.  With a buried stock tank, it is very easy since all you have to do is poke some holes in the bottom and fill it with dirt.  There aren’t tons of rocks to have to haul away.

I converted one of my older stock tanks last spring into a rose garden since I can’t take care of three anymore.  I had it filled with dirt and then planted it with roses, which were really beautiful and bloomed well.  A raised pond could be used for a small vegetable garden or flower garden.  I have a couple of older small stock tanks that I use for that purpose.

If the stock tank has been used as a raised pond, it is very simple to get rid of it.  Just advertise it in a local newspaper and sell it.  If you are renting you could use a small stock tank as a pond, and then when you move, drain it and move it to your new house or apartment.  So if you are considering putting in a pond, think about using a stock tank instead of a liner.  It is a viable alternative, which works very well and has many advantages over liners.