Here is to dome
in the spring after the plastic was removed. The water lilies were already out
and ready to bloom!
The new design (details below) using the nylon straps to hold the plastic clips worked very well. We have had our usual very strong spring winds and I have had no clips or plastic come loose! In a high wind the dome really shakes, moves and groans but nothing has come loose. There are no damaged areas on the grass since I did not have to put heavy weights on the edges either. The side supports helped keep the hoops from bending in also. That has prevented any collapse from snow or high wind. The angled rebar to hold the entire dome onto the ground appears to have been a success also, the dome didn't fly away. If you have extreme winds, >55MPH, I would try to find a light nylon net to put over the entire dome (or at least the middle section) and then attach the net to the ground with heavy duty rebar driven deep into the ground at a angle. That would keep the plastic from flapping and keep the dome on the ground.
The high quality greenhouse plastic has been great! It isn't cheap but will last for many seasons and is very strong. Even with a hole in it (accidents or to put the nylon straps through) it remains very tough and will not tear.
Water temp this past January was lower than the prior year. It would drop to 39 at the lowest. This was likely due to our poor snow fall this past winter. The snow seals the bottom edges to keep the wind out and helps insulate. The new design also puts less plastic and weight on the grass. I am looking into ways to better seal the bottom pipe to the ground. The problem is to not damage the grass with too much on it. The fish were still quite happy, no ice ever.
I have realized that there is an easier method for handling a top pool waterfall (or a upper streambed). I like to keep the pump and filter running all winter. I feel is maximizes water quality and avoids spring start up problems. As long as all the water is in pipes or inside the dome it will not super chill or freeze. The top pool was very awkward to cover. It is to the side of the main pond and required lots of special fitting to cover. More important I worried that a really heavy snow would collapse the part of the dome over the upper pool because it was less strong. That would run the risk of diverting the running water out of the pond and then a major disaster! I know realize that I can take a piece of pipe (large flexible will be easier) and attach it to the end of the hose as the hose comes through the liner in the top pool. The liner pipe seal has enough pipe sticking into the top pool to attach to. The extra pipe can then be ran across the upper pool and to the edge of the waterfall. The pipe will then let the water fall directly into the main pond. I can then make the dome cover fit the top edge of the waterfall and not have to cover the entire upper pool. As an alternative a separate length of pipe can be attached to your filter outlet and directed straight to the pond. Be sure the water does fall enough to aerate or add an air pump inside the dome (you want to pump only moist warm dome air into the pond to help keep temps up)
I have developed what I feel is the ideal method to medicate most all koi. It is to place a sliver of medication (human or vet supplied) inside a frozen green pea. The fish love peas and I can direct the medicated pea to the one fish that needs it. This delivers a good high dose of fresh medicine to just the fish that needs it. This really works well! Check out my other koi web site for details: Koi Medication
Here is to dome
in the spring after the plastic was removed. The water lilies were already out
and ready to bloom!
Heavy snow caused the center to collapse in the middle of winter. I put in center posts along the ridge pole to help hold the top up. Most posts sit on legs on the bottom of the pond as pictured. One post had to span the deep part of the pond because the center line was too close to the side of the drop off (see picture) Both worked well to keep the top from collapsing downward.
Vertical brace and foot pad 2" PVC spanning sides 1" vertical attaching to 3/4" hoops
See the home page for more details about this feature koidome
Although this prevented the top from collapsing we had another problem in the spring WIND!!
Santa Fe has occasional 50+mph winds in the spring. While there was good snow cover this was not a problem. When the snow melted and the wind really came up we had two new problems, the clips holding the plastic would snap off and the top would blow away! It was easy to replace but a nuisance. Putting a large number of rocks and bricks on the edge held the plastic down but messed up the grass underneath. There were two problems that contributed to the plastic coming loose. I have made three changes that I think will help.
In high wind I found that the half a hoop could collapse inward on the wind side while the top of the dome stayed up. The wind side would bow inward and become convex while the down wind side of the hoop kept its normal shape. The convex half would then spring back to its normal concave shape with great force and a snap. This would dislodge the plastic clips holding the plastic and the top would blow away. I worked on several ideas to make the hoop halves more rigid. I think this will work:
I cut and glued
a T connector into the lower part of the hoop and attached a 45degree elbow
joint. I placed it at a point where the 45 points slightly in towards the pond.
A section of PVC then goes from the 45 elbow down to the ground. I put the vertical
pipe over a piece of re bar to keep it from moving inward when the wind pushes
hard. These joints were glued in place.
The vertical
pipes are only about 1/3 up the sides of the hoops but seem to offer substantial
support to the hoop. Both the lateral strength and vertical strength are much
better with this addition. The more distance you have from the base of the hoop
to the water (and the more circular your hoop) the farther up the hoop you would
attach. If you have enough room it would be better to attach the elbow at a
little lower position on the hoop so that the support pipe angles in towards the
pond for better lateral and vertical strength. My hoops are relatively flat on
top and close to the water edge so I had no option.
I used short 4" clips to hold the plastic onto the PVC ribs along the ground. They would pop off in high wind. Weights helped but damaged the grass. It has been recommended to drill through the clip and into the PVC and then screw the clip to the PVC. This would be very strong but time consuming. PVC can be hard to drill straight into and hard to screw into. I decided to try this:
I punched a small hole
through the plastic and put a nylon strap (available at hardware or electronic
stores in many lengths and colors) through the hole and around the tucked under
plastic and around the clip. I then drew the nylon strap tight. It makes only a
small hole but holds the clip on very tightly. In the spring it will be easy to
cut the nylon with pointed wire snips and release the clip.
If the plastic stays in place it is possible that the entire dome could be blown away in a high wind. This is especially a problem if the wind can get under the bottom sides when there is no snow to seal the bottom. The bottom pipes need to be a tight to the ground as possible. The re bar that holds the hoops in place helps but is not enough. These re bar are vertical or even slightly pointed inward which can allow the hoop to lift off the re bar. Wide nylon straps over the top and secured by pipes set at a 45 degree angle away from the pond would be very strong but some what unsightly. I have tried two different methods to hold the bottom pipes down more securely.
This is a cross connector set
at a 45 degree angle with the top aimed away from the pond. It is in the middle
of each bottom pipe. A re bar is then driven through the cross piece at a 45
degree angle. Tie wire is tightly wrapped around the re bar at ground level and
then around the cross piece to help hold it in place. The angle is
opposite the direction the wind will try to lift the dome and should hold the
dome down well. We will see!
This is another idea. A T
connector is set into the bottom pipe and is turned parallel to the ground. A short
4" piece of PVC set into it. At the end on the PVC piece another T connector is
attached. This T has had its other two side arms cut off with PVC clippers. The
result is an opening wide enough to drive a re bar into the ground at a 45
degree angle (away from the pond) to hold the entire piece in place. Wire around
the re bar at ground level also helps hold the piece down. This has a leverage
advantage and may be stronger but takes a little more material and time to
build.
Make the dome an equal rectangle if at all possible. If all hoop segments are equal length and your rectangle is all 90 degree corners it will be much easier to build. It is better to go up and over plants/rocks and keep a straight line than to bend or make corners. If you measure the two diagonal distances across your dome and the two diagonal measurements are equal then all your angles will be perfect 90 degrees.
If possible make the dome bigger and taller. It is nice to have room to get inside the dome and to work in it.
In the spring cut the grass inside the dome as it grows! If you have grass inside the dome it will really start to grow in the spring. You need to get in with hand shears and keep it cut to a reasonable height. If you let it grow too tall (as we did) and then cut it the grass will die back and leave a brown spot. Try to avoid using heavy weights over grass to save the grass in the spring.
I hope this is helpful. If you have ideas or comments please let me know. My material suppliers are at the bottom of the home page
R Brad Stamm
Zone 5b-6a (7350ft elevation on side of mountain)