Let's talk liners and liner protection

YShahar

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OK folks, the time has come to talk of many things...

Specifically of pond liners and liner protection.
First, the soil situation: as I mentioned in my pond build post, I'm digging into something that is almost pure limestone, with very little actual soil in it. Think sharp angular rocks pointing in all directions. So I'm going to need more than the usual cushioning underneath my liner.

My first thought was to put in a 10 cm deep layer of sand. However, that won't help cushion the sides. In addition, if I buy in bulk, the 500 kilo bag(s) of sand would have to be dropped into my neighbor's front yard, and from there moved, one bucket at a time, down two flights of stairs to our front yard, around the house and then down another flight of stairs to our back garden. It's doable, but would add a huge amount of extra work, especially as I'll be doing it almost entirely on my own.

So here's what I thought to do, and you can tell me whether this sounds workable:

I've got 20 big concrete paving slabs measuring 45 x 45 cm by 5 cm deep. I'm thinking of covering the bottom of the deepest area beneath the liner with these slabs, as well as any part of the pond that will see foot traffic (shelves leading from the entry beach area down into the deep end). On top of the slabs, I'll add underlayment. For areas that won't have concrete slabs under the liner, I'll add extra underlayment, plus odds and ends (old carpet, styrofoam, etc.) that I have lying around.

What do folks think: overkill or not?

Now to the liner itself... I've priced Pondgard liner at local aquatics suppliers, as well as EPDM roofing material. Here is what I found out:

Pondgard 89 shekels / square meter (about $28 per square meter). So for a 7 X 10 meter sheet (70 square meters) the cost would be 6,230 shekels, or $1930.

Roofing liner from a building supply company: 870 shekels (about $279) for a roll measuring 10 x 20 meters (200 square meters). By comparison, the same size in Pondgard would cost 17,800 shekels (more than 20 times as expensive as the roofing membrane).

Now I'm aware that the pros and cons of Pondgard vs. roofing EPDM have been discussed on the forums. And of course, the guys at the aquatics stores swear up and down that regular EPDM is practically a doomsday weapon against fish. On the other hand, I talked to a guy who uses EPDM for roofing, and has also built some large fish ponds for a local park. "EPDM is EPDM!" he said. "It's all exactly the same stuff!"

So it was time to do an experiment. I went over to my favorite building supplier and bought a roll of 10cm x 200cm EPDM of the sort that would be used in sealing roofs. According to their website, this is the same stuff as used in the larger sheets, only cut much narrower (10 x 200 cm rolls is the smallest they have). I then went out and bought a cheap glass aquarium and 5 goldfish. I set up the aquarium with good filtration and some water plants and let the fish acclimatize for a month. I then moved two of the goldfish to a separate spare aquarium to use as a control group. I then cut a sheet of 20 cm worth of EPDM off the roll, rinsed it (giving it no more rinsing than I'd be able to do with a full-size liner out in the yard), and dropped it into the more established aquarium.

Results so far: all the fish are healthy and happy, and the ones in the EPDM-contaminated aquarium seem to spend as much time nosing around the stuff as they do nosing around the gravel at the bottom. So my inclination is to go with the roofing membrane (at 20 times cheaper and much wider rolls). Since it's sold only in 20 meter rolls, if I buy a 10 meter wide roll, I'll have plenty left over for a later bog filter and other side projects.

So folks, anyone see anything wrong with my reasoning here?

Go ahead. I can take it! ;-)
 

TheFishGuy

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I wont provide any advice on underlayment, as my opinion on it is not well regarded, but as far as the epdm liner situation goes, I could probably provide some advice.

Obviously you would be taking some risk with the roofing liner, but since you already did a good test, I think it should be fine. My pond liner comes from a company called firestone, which makes roofing liners, and I believe their pond liners are simply a rebranded version of their roofing materials. It has worked out fine for me, so I cant say that it will work out fine for you, but there is a good chance you would never be able to tell a difference.
 

YShahar

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Obviously you would be taking some risk with the roofing liner, but since you already did a good test, I think it should be fine. My pond liner comes from a company called firestone, which makes roofing liners, and I believe their pond liners are simply a rebranded version of their roofing materials. It has worked out fine for me, so I cant say that it will work out fine for you, but there is a good chance you would never be able to tell a difference.

Well, I haven't tested it with anything other than goldfish (which tend to be less fussy than koi), but I'm hoping it's a good indication. Of course, there's the chance that when I got to buy the roll of liner, I'll end up with something different than the test roll I bought, but it isn't likely. I think our liner is also from Firestone, though the roofing guy I spoke to said that he buys his from a company called "Carlisle". I haven't found a retailer that carries it though.
 
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who makes the roofing edpm ? carlise? firestone? also most roofing products have a dust on them im told its to prevent sticking while rolled up and its a fire retardent. wash it off good . maybe wash it fill the pond and then drain it you should be fine
 

YShahar

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who makes the roofing edpm ? carlise? firestone? also most roofing products have a dust on them im told its to prevent sticking while rolled up and its a fire retardent. wash it off good . maybe wash it fill the pond and then drain it you should be fine
The stuff I priced so far is from Firestone, but the roofing guy I talked to buys his from Carlisle. I'm going to be talking to him about redoing the roof on our house ahead of putting a solar array up there, so I'll ask him if he can buy the stuff for us. I wasn't able to find a supplier online in our area for Carlisle, so this guy must get it through a builder's supply that doesn't sell retail.

And yes, I'll definitely wash it down well! And I'll be washing it down again once it's in the pond, as I rock things in. I'm really looking forward to getting to the rocking in stage!
 
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I think you have a good plan. I do not know for certain what the difference is between regular roofing membrane and pond liner, though it is often speculated that the roofing membrane may come into contact with contaminants during production that are not fish safe, may have an algaecide treatment, and/or may have an anti-stick additive that washes off (like @GBBUDD mentioned).

In any case, it's used all the time as a less expensive alternative to the pondguard liner and I don't think I've ever heard of a scenario where any harm that came to a fish could be traced back to the liner. It's a risk I would personally take for the 20x cost difference.

If the special pond guard liner killed your fish, the best you'd get is an apology and a replacement liner, so I don't see the value in the exorbitant expense unless you're breeding show koi or something.
 

TheFishGuy

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oop! I left all of that shiny silver dust on my liner, we will have to see how that works out.
 

addy1

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We have a bit of dirt with a ton of rocks, shale. I used a liner from bend tarp and liner. PPL36 called something else now. It is tougher than EPDM, lighter and less expensive, well years ago it was.

HDPE is one of the terms used for it now. REINFORCED POLYPROPYLENE LINER

I put some carpet padding under mine, have driven a tractor on it (in the bog loading the pea gravel) it survived all. Still going strong. Not sure if you can get something of this sort over there.
 
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We have a bit of dirt with a ton of rocks, shale. I used a liner from bend tarp and liner. PPL36 called something else now. It is tougher than EPDM, lighter and less expensive, well years ago it was.

HDPE is one of the terms used for it now. REINFORCED POLYPROPYLENE LINER

I put some carpet padding under mine, have driven a tractor on it (in the bog loading the pea gravel) it survived all. Still going strong. Not sure if you can get something of this sort over there.

Tis HDRPE; there's a difference and that's more than likely what you have, Boss. It IS tough stuff and doesn't like being folded; ask me how I know!


Can we send Queenie with the next shipload (yachtload??) of honey to the Mediterranean with a roll of HDRPE for our new cameralady? Seems there were a few loose coins in the couch last week...plus, I needs get her outta ma hair fer a bit; me and Dime gonna spruce the camp up and well...we don't need nobody tellin' us to move the furniture 2 inches to the right, 4 inches to the left, or that our lava lamp is cliche....not to mention all the football pictures we wanna hang up...Jack is especially keen on not tripping over her crown all the time, too...:cool::p:D:eek::oops::rolleyes:;)
 
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OK folks, the time has come to talk of many things...

Specifically of pond liners and liner protection.
First, the soil situation: as I mentioned in my pond build post, I'm digging into something that is almost pure limestone, with very little actual soil in it. Think sharp angular rocks pointing in all directions. So I'm going to need more than the usual cushioning underneath my liner.

My first thought was to put in a 10 cm deep layer of sand. However, that won't help cushion the sides. In addition, if I buy in bulk, the 500 kilo bag(s) of sand would have to be dropped into my neighbor's front yard, and from there moved, one bucket at a time, down two flights of stairs to our front yard, around the house and then down another flight of stairs to our back garden. It's doable, but would add a huge amount of extra work, especially as I'll be doing it almost entirely on my own.

So here's what I thought to do, and you can tell me whether this sounds workable:

I've got 20 big concrete paving slabs measuring 45 x 45 cm by 5 cm deep. I'm thinking of covering the bottom of the deepest area beneath the liner with these slabs, as well as any part of the pond that will see foot traffic (shelves leading from the entry beach area down into the deep end). On top of the slabs, I'll add underlayment. For areas that won't have concrete slabs under the liner, I'll add extra underlayment, plus odds and ends (old carpet, styrofoam, etc.) that I have lying around.

What do folks think: overkill or not?

Now to the liner itself... I've priced Pondgard liner at local aquatics suppliers, as well as EPDM roofing material. Here is what I found out:

Pondgard 89 shekels / square meter (about $28 per square meter). So for a 7 X 10 meter sheet (70 square meters) the cost would be 6,230 shekels, or $1930.

Roofing liner from a building supply company: 870 shekels (about $279) for a roll measuring 10 x 20 meters (200 square meters). By comparison, the same size in Pondgard would cost 17,800 shekels (more than 20 times as expensive as the roofing membrane).

Now I'm aware that the pros and cons of Pondgard vs. roofing EPDM have been discussed on the forums. And of course, the guys at the aquatics stores swear up and down that regular EPDM is practically a doomsday weapon against fish. On the other hand, I talked to a guy who uses EPDM for roofing, and has also built some large fish ponds for a local park. "EPDM is EPDM!" he said. "It's all exactly the same stuff!"

So it was time to do an experiment. I went over to my favorite building supplier and bought a roll of 10cm x 200cm EPDM of the sort that would be used in sealing roofs. According to their website, this is the same stuff as used in the larger sheets, only cut much narrower (10 x 200 cm rolls is the smallest they have). I then went out and bought a cheap glass aquarium and 5 goldfish. I set up the aquarium with good filtration and some water plants and let the fish acclimatize for a month. I then moved two of the goldfish to a separate spare aquarium to use as a control group. I then cut a sheet of 20 cm worth of EPDM off the roll, rinsed it (giving it no more rinsing than I'd be able to do with a full-size liner out in the yard), and dropped it into the more established aquarium.

Results so far: all the fish are healthy and happy, and the ones in the EPDM-contaminated aquarium seem to spend as much time nosing around the stuff as they do nosing around the gravel at the bottom. So my inclination is to go with the roofing membrane (at 20 times cheaper and much wider rolls). Since it's sold only in 20 meter rolls, if I buy a 10 meter wide roll, I'll have plenty left over for a later bog filter and other side projects.

So folks, anyone see anything wrong with my reasoning here?

Go ahead. I can take it! ;-)
Can you at least rough in the bog now rather than later? A single liner that extends into the bog is easier to keep water tight between them. I know you've got a lot of work going on, and the bog may sound like a daunting additional task right now.
The roofing alternative sounds as well tested as you can get. Great job. You could do another test as your pond cycles and put a few goldfish in first rather than koi. You'll know in a couple of weeks if there's a problem. (sorry, goldfish, but you'll do fine!)
 

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Tis HDRPE; there's a difference and that's more than likely what you have, Boss. It IS tough stuff and doesn't like being folded; ask me how I know!


Can we send Queenie with the next shipload (yachtload??) of honey to the Mediterranean with a roll of HDRPE for our new cameralady? Seems there were a few loose coins in the couch last week...plus, I needs get her outta ma hair fer a bit; me and Dime gonna spruce the camp up and well...we don't need nobody tellin' us to move the furniture 2 inches to the right, 4 inches to the left, or that our lava lamp is cliche....not to mention all the football pictures we wanna hang up...Jack is especially keen on not tripping over her crown all the time, too...:cool::p:D:eek::oops::rolleyes:;)


Since we are talking liners here, which kind would you like for your coffin?
Although we would still prolly find you haunting the halls of the castle.
Need lots of duct tape soon..................
1644973032821.gif
 
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epdm has one enemy the sun i would cover every inch out there in Israel.

Carlisle is probably # 2 in rubber roofing epdm anjon being third back when they had quality issues with imperfections in the material if i remember correctly.

If my liner isn't under a rock then i do have fabric covering it and allowing nature to grow what she will onto the fabric takes a year or two maybe a culture of what you want to grow there but in time well worth the effort
 

YShahar

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Tis HDRPE; there's a difference and that's more than likely what you have, Boss. It IS tough stuff and doesn't like being folded; ask me how I know!
I did a quick search of the various builder's websites and wasn't able to find the reinforced stuff. I could theoretically get plane HDPE, though it looks like I'd have to find a construction company willing to sell me offcuts.
Can we send Queenie with the next shipload (yachtload??) of honey to the Mediterranean with a roll of HDRPE for our new cameralady? Seems there were a few loose coins in the couch last week...plus, I needs get her outta ma hair fer a bit; me and Dime gonna spruce the camp up and well...we don't need nobody tellin' us to move the furniture 2 inches to the right, 4 inches to the left, or that our lava lamp is cliche....not to mention all the football pictures we wanna hang up...Jack is especially keen on not tripping over her crown all the time, too...:cool::p:D:eek::oops::rolleyes:;)

Oy, lava lamps are so last century!
 

YShahar

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epdm has one enemy the sun i would cover every inch out there in Israel.

Carlisle is probably # 2 in rubber roofing epdm anjon being third back when they had quality issues with imperfections in the material if i remember correctly.

If my liner isn't under a rock then i do have fabric covering it and allowing nature to grow what she will onto the fabric takes a year or two maybe a culture of what you want to grow there but in time well worth the effort

Very good advice about the sun! The pond will be partially shaded, but in August, it will be getting some serious UV. I do plan on covering every square cm with underlayment over the liner, plus rocks.

Now here's an interesting possibility: check out the photos on this guy's site here: http://www.japan-garten-kultur.de/japanische_gaerten-neue-projekte.htm . It looks like he's covering the liner with underlayment and then pouring a fairly thin layer of cement over it. You can see the same technique in some of the other photos.

Now, I've seen where people build small indoor or patio fish tanks using cement over styrofoam and cloth, so I'm wondering whether this technique would work for me. If not over the liner, then under it to give more protection from the rocks and gravel underneath.

Also, what do you think about my idea of using my large cement pavers under the liner for added protection? Overkill or not? Would those be safe to use on top of the liner as well (with underlayment between, of course)?
 

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