Designing a Backyard Pond System

[Ellen Roelofs]

My partner, Molly, and I are buying a house together in Grand Rapids, Michigan and are excited about building an AP pond system , despite the fact that we don't really know what we're doing.

I would like to dig a pond in the back yard which is flat and level with the house. I am imagining 20-25 ft diameter with 3-7ft depths, and enclose it with raised AP gravel beds around the edge (relatively), except at a small dock.  In this configuration, the pond would hold around 4 times the volume of the GBs. I am hoping to keep yellow perch in the pond year-round, and to use lava rock for its porosity, covered with a layer of river rock for easier gardening.

 

We are taking a lot of landscaping queues from the forest garden model, as a means of both growing our own healthy food and of shielding the house from the very busy road.  I plan to water these fruit trees,etc., in the yard with water from the fish pond, and to top off the pond with water from the rain barrel or the city.  

 

This system is, in my mind, as much of a landscaping feature as it is a means of intensive food production. I am not interested in cramming as many fish as possible into that pond.  I am interested in keeping maintenance manageable!

 

I need to figure out what flood/drain mechanisms will be best suited to this application.  I first thought of using a loop siphon but didn't think our real estate agent would approve of a whole bunch of loopy hoses hanging into the pond. She keeps reminding us that we will one day need to sell the house... 

anyway, are there more elegant solutions we should be considering?  I've wondered about putting a 90 degree bend in the stand pipe of a bell siphon, so it's plumbed through the side at the bottom of the GB.  Would this work?

[Tom OBrien]

I haven't had problems with squirrels so far...but it looks like the local squirrel population is booming. One of our neighbors is an avid squirrel feeder.

My nemesis is the dreaded plum curculio beetle.

[Ellen Roelofs]

6 fruit trees can be a lot of fruit!  Squirrels are a perennial problem... but now our squirrel population is diversified!  We have grey and brown, and now black squirrels are moving in!  We also see some reds... welcome to the squirrel melting pot that is SW Michigan!

I think this is exciting. For my undergrad geography thesis I wanted to make an android app to record squirrel sightings.  I had a little less flair then, I guess... I hadn't figured out yet that nobody cares about your undergrad thesis, and I wasn't sure it was respectable.  That was totally a missed opportunity, lol.

[Ellen Roelofs]

TC, those new beds are looking nice!  Thanks a million for the arm-in-the-gravel-guard tip!

TCLynx said:

I do 2' deep grow beds all the time.  Just make sure the gravel guard is big enough for your arm and that you can pull the stand pipes out to clear the holes around the base of them since certain plants will send roots to the plumbing and simply pulling the stand pipe out to clear the roots is pretty easy as long as you catch it before they actually fill the drain line.

As to ponds and winter protection.  It largely depends on how much extra protection you might give the pond for the winter.  For may years my mom's 2 foot deep ornamental pond in Alden, Michigan kept the goldfish alive without even an air hole but then they got one really cold winter without much snow and the pond froze to the bottom and the fish all died that winter.  Some form of insulating cover might be all you need in case of not being buried in snow.  I would not recommend a large fish load over winter though.

[Tom OBrien]

With just the 2 asian pear trees bearing fruit we give away a lot of pears each fall to friends and family. The cherries will come much earlier so I'm looking forward to another harvest season if I can keep them away from all the other wild fruit lovers that visit our yard.
 
Ellen Roelofs said:

6 fruit trees can be a lot of fruit!  Squirrels are a perennial problem... but now our squirrel population is diversified!  We have grey and brown, and now black squirrels are moving in!  We also see some reds... welcome to the squirrel melting pot that is SW Michigan!

I think this is exciting. For my undergrad geography thesis I wanted to make an android app to record squirrel sightings.  I had a little less flair then, I guess... I hadn't figured out yet that nobody cares about your undergrad thesis, and I wasn't sure it was respectable.  That was totally a missed opportunity, lol.

[Tom OBrien]

TCLynx, One other deep bed design question. How are you doing the draining or siphoning on your beds. I saw a picture you posted with an external loop siphon but it looks like you have something different on the beds in the picture above.

TCLynx said:

if only that would keep squirrels at bay

[TCLynx]

Most of my deep beds are timed flood and drain using indexing valves to flood the beds in sequence and I just have a stand pipe with holes in them.

I only really had one really deep bed that was siphon flood and drain.

[Ellen Roelofs]

I read through much of your thread on indexing valves when it was active... it might be time for me to dig that back up for a little refresher.  How do you get it to consistently fill to the desired height?  I kind of get that the valve is adjustable, but what happens when the pump slows down?

I have been wondering about the effects of back pressure on the siphons.  I was imagining having several beds draining to the same pipe back to a sump tank.  If that pipe fills up, say, if the siphons drain simultaneously and the pipe is not big enough, could it push air up into the bell and break the siphon?  I have so much learning to do when it comes to plumbing that I don't even know where to start.

TCLynx said:

Most of my deep beds are timed flood and drain using indexing valves to flood the beds in sequence and I just have a stand pipe with holes in them.

I only really had one really deep bed that was siphon flood and drain.

[Tom OBrien]

OK. I'm not ready for indexing valves just yet. I have a pretty small system, so I think I'm going to stick with the siphons for now and see how I do. Someday, with luck, maybe I'll make the big leagues...

But as always, thank you for your help.

TCLynx said:

Most of my deep beds are timed flood and drain using indexing valves to flood the beds in sequence and I just have a stand pipe with holes in them.

I only really had one really deep bed that was siphon flood and drain.

[Tom OBrien]

Hi Ellen, I'm not sure how many of your beds would be draining at the same time with an indexing valve, but I think there are a couple things you can do to minimize siphon problems with back pressure in the drain. One would be to size the main drain pipe so that the cross sectional area is about equal to the area of the of the number of siphons that might be going at the same time... a 1" siphon drain has an area of 0.79 sq in. A 3" drain would give you a cross sectional flow area of of 7 sq in. Theoretically you'd be good for maybe 8 beds draining at the same time if it was all uniform constant flow. So probably 5-6 max. would be safe. You could also leave an air gap in the connection of the siphon to the main drain. That might overflow if the main drain pipe backs up, but would keep pressure changes inside the drain from affecting the siphon, I think.

Ellen Roelofs said:

I have been wondering about the effects of back pressure on the siphons.  I was imagining having several beds draining to the same pipe back to a sump tank.  If that pipe fills up, say, if the siphons drain simultaneously and the pipe is not big enough, could it push air up into the bell and break the siphon?  I have so much learning to do when it comes to plumbing that I don't even know where to start.

[Ellen Roelofs]

Thanks Thomas,

I thought about connecting the siphons to the main drain by using a hole saw to make holes along the top of the main drain pipe, but was concerned that water would splash up through the gap from the head pressure coming out of the siphon each time it drained.  I abandoned the idea for this reason... until you mentioned it...

Now I am thinking I should hard plumb the siphons to the drain and place small overflow stand pipes in the main drain pipe reaching to an elevation below the top of the lowest growbed.  This way if pressure backs up, water will flow out the top of the overflow pipes and prevent water from backing up into the beds.

[TCLynx]

Don't use the indexing valve with Siphons!!!!!  Indexing valves are a timed flood and drain device.  Use stand pipes with the small holes at the bottom for timed flood and drain.  Run the pump long enough that the beds flood fully and remain flooded and flowing down the top of the stand pipe for a bit before shutting off and going to the next bed.

People who have used the indexing valve and put in siphons anyway, usually eventually contact me complaining that the pump slowed down (maybe some leaves or something over the grill) and the valve didn't fully engage which had water flowing out all ports at a reduced rate but not fast enought to kick over the siphons so all the beds were flooded and the fish tank or sump tank got really low.  This won't be nearly such an issue if it's stand pipes since it would simply mean all the beds get a bit of water but they are all draining constantly anyway so the fish tank level might be a little low in such a situation but it wouldn't be as low or as prolonged a situation.

If you need breather pipes on your drains, you can do it with Ts and a riser pipe.  If you are doing siphons on large beds into a 3" drain, I would probably only do 3 beds per drain line if the beds and siphons are really big.  On my 300 gallon system I use 3" drain lines and hook 3 beds to each drain line just because the layout works well that way one drain line down each side.  You probably could get away just fine with 6 beds on a single drain line with the indexing valve timed flood and drain but that is only really convenient if all 6 beds are in a straight line.  The way I have the zone pattern on my 300 gallon system the valve alternates rows filling so I have a convenient way to know if the valve has been functioning properly.  If all is well, there is always water coming out both drains into the fish tank.  At a quick glance I know that if one drain is not flowing water back into the fish tank, I'd better make sure nothing is in the valve jamming it up or slowing down the pump.  If no water is flowing out either drain line, then I know the pump hasn't been running and I'd better figure out why and fix it.