New Pond Construction with elevated bog, brainstorming session before the build.

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What I want to do is use a 6’ diameter galvanized stock tank as the main part of the pond and the black plastic premade pond liner as an elevated bog filter. The water will return to the main tank by way of the waterfall.

I am going to tuck it back into this area in the garden, I figure I will need to excavate 6-8”, fill with 2A limestone, tamp and level the area before I put the tank down. The bog will be supported by a base built on cinder blocks that will also have a compacted base layer of stone underneath it.
IMG_20200617_190816.jpg


Is this black plastic the PVC I should be avoiding? If that’s the case I will probably abandon it and search for a new container. I got this for free so I have no attachment to it
IMG_20200617_190925.jpg


Referring to Addy1’s thread “Bog Building” the sizes of these two containers fit with in the suggested range. The stock tank will have no more than 390 gallons in it, the upper pond has 22.5 gallons so by volume the bog will be about 6 % of the volume of the main tank. Surface area wise the stock tank will have 28.3 square feet the, bog has about 7 square feet so 25 % of the surface are of the main tank good to go right?

I don’t plan to have large fish or a ton of fish so I am hoping this will be sufficient to filter the pond. I have heard conflicting things about the galvanized tanks leeching zinc and killing fish so I am going to coat the inside of the thing to be safe. Any products out there that are suggested for that? I am currently thinking about using a grey flex seal, I would really like to use clear and keep the look of the steel tank but I think grey would be better as I will be able to see if I miss any spots or notice if it starts to fail down the line.

For a pump I figure I need about 200-250 GPH to circulate the water through the bog. The weir on that plastic pond liner is 4” from something I read, to maintain a waterfall I think need 100 GPH for every inch of weir so I am looking for a 400 GPH pump. Am I correct on my calculations for the for the pump. I plan on using a submersible pump to keep the sound of the pump to a minimum.
 

addy1

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The preform pond will work fine. The black pvc is liner you should not use.
The main issue with the preform, I used three, all cracked, eventually over winter, all constantly went unlevel. I tossed them,mine were in the ground.
But it sounds like your build might be just fine.
 
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I agree with addy i myself am not a preform plastic fan in the north east ice can have it's way with it very easily and it's realy not deep enough to keep fish in . i know you wanted to use it as the bog but to elavate the preform with no support i am afraid it a problem in the making. The flex seal will work but it is not all that durable. What you will pay for the flex seal you could buy a epdm rubber liner
 

mrsclem

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I currently have a 75 gallon preform. It's been in use for 5-6 years and have had no issues with it cracking however it has now become unlevel. I built a wooden frame from 2x12 pressure treated lumber, set the preform inside and backfilled with dirt.
 

addy1

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Mine where in the ground, they both cracked I fixed it, then they both went un-level big time and re-cracked so I yanked and put in liners.
 

Mmathis

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A plastic preform pond and PVC liner are not the same thing. PVC liner refers to a type of sheet liner. PVC liners tend to be more fragile than rubber, and don’t stand the test of time and weather. Are you planning to line the galvanized tank? This is where a “sheet liner” would be used. There is another thread currently that addresses galvanized tanks — lining it would be preferable as these tanks can be toxic to fish. Just curious, though, why would you use limestone and not sand or dirt?
 
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That's going to be a pretty spot for a pond! I agree that the preforms are prone to cracking. I'm the kind of person who hates re-doing anything, so that would bug me. But if you have it and want to use it and accept that it may eventually fail, I'd say go for it!
 

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