30' x 60' above ground watergarden project

[Willy64]

Hello all!

I have been scouring the internet for information regarding installation of a properly functioning watergarden and my head is beginning to spin with so many options and accessories! But I think I have come to the right place where I can engage with pond enthusiasts and all those more experienced than I. Hopefully someone here can help guide me as I embark on this aquatic journey

So here's the setup -- a 30' x 60' water garden, above ground, wooden frame to hold the water, 45 mil EPDM liner with underlayment, depth ranging from 10" to 1.5' (the site on my property slopes quite a bit north to south), from my estimate it will hold 20,000 gallons or so, little to no fish (maybe small gold fish at some point), few aquatic plants.

What I'm curious to know is what I absolutely need to do in order keep the water healthy and clear, deter algae growth, and provide an environment for aquatic plants to flourish. Mainly I'm looking for details on whether or not I need pumps, filters, or aerators. A few questions I've thought of are below.

- Does something of this size and depth with no fish need to be continuously circulated?
- Do you recommend installing a filter?
- Does this type of watergarden need to be oxygenated? (I'd rather not have a waterfall)
- If anyone has experience building an above ground frame to hold a pond, please comment on how you prevented the sides from bowing.

Excited to hear from you!
-Willy

 

[Lisak1]

30'x60'? Wow! That's a heck of a water garden. I think you would need to do a bit of engineering to make sure your walls can support the weight. That's totally not my thing, but I'll bet someone here can help you with that.

My question is - what kind of a water garden are you planning that will have few aquatic plants and few or no fish?

 

[Willy64]

Eventually it will have many plants, and hopefully it will be able to support small quantities of fish. But to start out, I am more concerned with creating a healthy water environment for only a few types of plants. As time goes on, I'd like to add additional plants and see how they change or influence the water quality.

My main goals as of now are to 1) establish a system that keeps the water clean and 2) create an environment suitable for introducing plants in the future.

 

[dieselplower]

I would want some circulation. Put a pump in a skimmer and be done with it. Personally if I didn't want many fish, I would get a couple fish of the same sex. Otherwise they will multiply. With only a couple fish and 20,000 gallons, you won't need to worry about a filtration or feeding. The plants will take care of it. The skimmer will provide circulation and collect leaves, flower petals, and other stuff that would otherwise sink to the bottom and become algae food.

 

[j.w]

Willy
I'd do the skimmer deal like DP says and any fish you put in will multiply so be prepared to try and catch the suckers to give away and that might be hard w/ all those plants in there. Those buggers are fast!

 

[mrsclem]

Hello Willy- I have 2 ponds built above ground due to a slope. 11x13 with depth3-4 1/2ft and 10x10x5. I used 2X12 lumber and 4x4 posts set in concrete. With the size you are planning you will have to have joints on the sides. I would recommend using block if possible. You might get away with the size if you keep the depth down but if something gives way it would be a disaster. I have my posts set 2 1/2' apart and set in 36" concrete and the sides have still bowed.

 

[Meyer Jordan]

The aquatic plants, in the right quantity, will keep the water clean. You will certainly want to provide circulation if, for no other reason, to deter mosquito breeding.
I am more concerned with the integrity of a wood frame wall support. You will be dealing with an enormous amount of weight which will translate to considerable hydraulic pressure on the walls. Your estimate of 20,000 gallons translates into over 83 tons in weight. A re-enforced block wall would likely be necessary.

 

[Willy64]

Awesome, thanks for the responses! Very informative and helpful as i begin to dive into this project.

A few more questions I could use help with after hearing your guys' input.

• Any specific recommendations on a skimmer that will effectively provide circulation for this size pond? What do you think would be the minimum size skimmer/ pump would be?
• Any specific recommendations for plants that will keep the water clean as well?

Good points about the framing of the wall -- I plan to install kickers to support the sides from bowing out. Either with wood kickers or drilling them directly into the concrete.

 

[callingcolleen1]

I have my top pond two feet dug down and one foot built up, and I used landscaping ties and pounded in big nails years ago and it is still strong and I can walk on it! Then I covered the one edge with rocks and glued them in place and stuffed moss into cracks. I love it and it makes reaching into pond really easy!

this is of the lower ponds that are partly build up.

 

[Willy64]

Also, for circulation. Do you think a few submersible pumps in the corners would suffice to move around water?

I'm thinking this might be a better option since a skimmer might suck up floating plants.

 

[sissy]

I don't have a skimmer ,no need for 1 since leaves usually do not blow into the pond .To move the top water I use my own made up system .It keeps the water on top moving and is now under my bridge

 

[OzarksGuy]

Willy, I agree with Callingcolleen, water pressure shouldn't be a big problem at a maximum of 1.5 feet depth. But because the total volume would cause quite a flood if lost, I'd suggest that if you excavate for the uphill portion, use the excavated soil to add support to the downhill side where the water is highest relative to the ground.

The other concern I'd have would be evaporation over time concentrating minerals/pollutants in the water with that large surface area. Also, depending on temp, humidity and rainfall, you may need to run water in to keep the level where you want it. That's a lot of water to replace if you run into a hot dry spell. You might consider starting out a bit smaller at first to gather data and get experience, then increase size by adding ponds. You have the slope, so they could even be connected with a stream or channel so overflow could move from upper to lower ones if desired.

Animals sometimes chew through liners, or they fail for other reasons, so that would be another benefit of multiple smaller ponds - less flood water for the neighbors (or you, if it's uphill of your house). Good luck, whatever you do.