River Rock vs Pea Gravel

[waynefrcan]

Ya could be!

I'm no algae expert but doesn't climate and location play a big part in algae production? LIke Arizona hot all year round compared to UK, or Canada which has only 3 hot summer months [excluding BC lol}?

And what happens to the algae in the water? Does it over time die and fall to the bottom to cover the liner? I see also the algae here is brownish but in many ponds it's really green.

All I know is I clean the skimmer filter bio pads once a week and the waterfall weir filter bio pads once a month and they all plugged full of floating algae that never had a chance to cling to anything.

Waterbug will know! Ok your mortared rock pond doesn't look like an alien spawning ground lol

 

[GreatDanesDad]

Ok guys, you have me decided to go with no rocks in the bottom, although I loved the mortared rock, were always working with small pockets. So I got lucky and found a bunch of liners that although are not big enough alone, will splice together nicely. So here is the next question. If I have to seam the liners anyway, should I cut the liners to fit my very square pond so that I have no wrinkles in the liner when it is laid out? How long do the seams last. It is unfortunatly PVC liner instead of EPDM. And recomendation on tecnique to use to splice or materials that are a MUST?

 

[taherrmann4]

I would go with as few splices as possible, the more you have the greater the chance of not getting it seamed together correctly.

Here is a pic of my rocks on the ledge, like i said earlier in the thread my rocks sit about 3" below water, and then there is a pic of the bottom of my pond all covered in algae. You can barely see the wrinkles. I have a few large rocks in the bottom just to give it some characheter and to help hold the liner down when we get 3-4" of rain in a short amount of time, lots of clay soil here.

 

[Waterbug]

Couple of things...

Algaecide vs Algae Resistant
Algaecide is not added to any liner. That liners are "algae resistant" is mostly a marketing term that came from the roofing industry were a slick EPDM membrane is not affected by algae growing on it. Algae still grows on it just fine, but the membrane is not affected at all. Previous roofing materials were adversely affected by algae growing into the materials and reducing it's life span. So marketing roof liner as "algae resistant" was a big plus.

For a brief time sellers of pond liner, seeing what the roof suppliers were doing, thought they could also increase sales with the "algae resistant" claim. Hoping inexperienced people would thing that meant they wouldn't have any algae problem. A buck is a buck. But that marketing scheme kind of backfired when people in pond forums started talking about "algaecide" leaking out and killing plants, and then fish got added too for good measure. The pond liner sellers backed off and today you rarely read a seller making the "algae resistant" claim as the profit in the claim dried up.

This myth really got legs during the years of The Great Pond vs Roof Liner War. "Algae resistant" was translated into "algaecide" by roof liner opponents to make baseless claims sound more valid. Appearing right at the expense of being right has always been the cornerstone of any bar room or online discussion.

Algae species
Whether an algae attaches to a liner or doesn't is a function of a specific species. The Algal Collection of the US National Herbarium has collected 320,500 kinds. There could be a million species of algae, no one knows. Some attach to stuff, some don't. Some can attach to slicker surfaces than other species. Generally the smaller the species like more likely they will get a good bond to liner.

Location on the planet I don't think has a lot to do with the kind of algae you can have. There are different species, but for the various types I think every environmental niche is filled around the world and has been for millions of years. Most ponds I assume would have maybe 3 different species of algae at any one time. Some die back, some come on, at different times, temps and just plain life cycle.

That any one person can imply, that because a pleasing algae covers their liner, that all liners will be covered in the same pleasing algae mistakes luck for wisdom. Plus "pleasing" is in the eye of the beholder.

Rock hand wringing
As for rocks...that a person would build a $2000, $5000 or $10000 pond primarily as a visual garden element and then compromise on rocks for fear of maintenance when for about $100 in mortar and very little extra effort the maintenance issue goes away completely is a head scratcher for me. I completely understand people preferring the look of bare black liner, if kept clear of algae, can really make fish pop. It's the people that want the look of rock but compromise and go with bare liner that is a puzzler.

 

[Mucky_Waters]

Waterbug is likely right about the algaecide not being added to the liner material, I don't know as I have never looked into it. I do know that it is added to other material that I work with, like certain types of building membranes and acrylic stucco and paint, so I was assuming the EPDM rumors were true.
As for the mortared rock covering the liner, I think it looks pretty good and makes sense as far as protecting the liner. How many ponds have you done like this Waterbug? Do you have more pictures? Do you always mortar and rock up the sides too? Have you ever had any issues with cracking? Freeze thaw cycles?
I do think it might be a bit of a challenging job for those who have never worked with mortar and rock before, but could very well be worth it for the liner protection alone.

 

[waynefrcan]

Ok guys, you have me decided to go with no rocks in the bottom, although I loved the mortared rock, were always working with small pockets. So I got lucky and found a bunch of liners that although are not big enough alone, will splice together nicely. So here is the next question. If I have to seam the liners anyway, should I cut the liners to fit my very square pond so that I have no wrinkles in the liner when it is laid out? How long do the seams last. It is unfortunatly PVC liner instead of EPDM. And recomendation on tecnique to use to splice or materials that are a MUST?

I don't understand your design?

Most ponders go with a 1 piece liner to avoid seams. For PVC have no idea about seaming as it is not what most ponders use. The liner manufacturer might have recommendations. How flexible is it?

 

[Waterbug]

If I have to seam the liners anyway, should I cut the liners to fit my very square pond so that I have no wrinkles in the liner when it is laid out?

Has to be your call. This is not normally done except in factory type conditions. Those companies make drop in liners that are seamed to fit the pond shape.

How long do the seams last.

Between 3 seconds and the life of the material. All materials have different lives. PVC has to be completely covered, normally in mortar, or it only last a few years, like under 5, as little as 2-3 yrs. If this is used PVC...well, who knows. Could fail as you're installing it.

It is unfortunatly PVC liner instead of EPDM. And recomendation on tecnique to use to splice or materials that are a MUST?

Use manufacturer directions. All steps are a MUST.

Wait until you check out the cost of seaming liners together. I'm guessing way cheaper to buy a new liner. When you add in the risk...could end up being pretty darn expensive. I like reusing material, but I generally change the design to fit the material. Scraps can be used to make tiered ponds, streams, falls, bogs, filter chambers.

 

[Mucky_Waters]

You see the reason I ask about the freeze thaw cycles with with rock and mortar over the liner is I would be concerned that when the water freezes and thaws it expands and contracts, and I would think that movement would cause the mortar to crack and loosen, and maybe eventually break apart. Now this would only happen along the shoreline on the sides of the pond (like you see in Waterbug's pictures), not at the bottom of the pond, and only in climates where you get freezing weather. This wouldn't be a problem with loose stacked rocks along the shore, as the loose rocks would just shift and move freely in the freeze thaw cycles. Nor would it be a concern in places where they don't get freezing temps.
Perhaps this is the reason more people don't rock and mortar over their liners.

 

[Craig58]

I'm not sure WB has much freezing in AZ. But I could be wrong. I'm kind of with you Mucky and would be hesitant to do rock and mortar over a liner where it would freeze. Any water getting between the mortar and liner will almost for sure crack the mortar within a couple of years, if not the first year if it freezes. Near the surface on the sides would of course be where the issues would happen. Anything 12-14" below the water line would probably be fine. And I think in most ponds it wouldn't look that good if you did just the bottom and not the sides.

Now if you plan to add solar heater or something similar into the system then I'd be all for it. The mortared rock look that WB shows in the photos is really nice. I wish I could do it here.

There was a company years ago I saw that offerred a liner printed with a rock design. Never used it and I don't know if it is still available or not. At the time, I didn't like the look because it was too 2-dimensional and didn't look natural to me. Maybe with today's technology they have improved it?

Here is one but it is only a 20ml liner: http://www.pondandga...nd-liner/Detail

Craig

 

[Mucky_Waters]

Certainly a little cracking wouldn't hurt anything, but I've seen a case where people build a concrete ledge around the pond that was partially submerged, and the frost heaving was enough to crack it and push portions of it a few inches in towards the pond. In this case I don't think it was the water freezing, but rather the wet ground froze and expanded and the pond water didn't, so there was in imbalance in pressure, and ice always wins. Not a total disaster as they were able to push it back together in the spring, but had it been the top of a wall that extended to the bottom of a pond it might not have been as simple a mater as just pushing it back.
I still like the idea of having a concrete layer protecting the pond bottom, wouldn't even have to have rocks in it for me. I just like the idea of being able to walk around and working in the pond without worrying about poking a hole in the liner. This spring when I was putting in my rocks and lily pots I was about to climb into my pond with some rubber sandals on and fortunately just before I hopped in I noticed I had a piece of wire sticking out the side of one of my sandals. After that I only went in in my bare feet.

Personally I'm not too crazy about those printed liners Craig, probably just as easy, and cheaper, to start the edge rocks below the water level and hide the liner.

 

[Waterbug]

I'm not sure WB has much freezing in AZ. But I could be wrong.

In Phoenix there is very little freezing.

Any water getting between the mortar and liner will almost for sure crack the mortar within a couple of years, if not the first year if it freezes. Near the surface on the sides would of course be where the issues would happen.

It's a misconception that ice busts everything. An enclosed space is required. In water pipes for example the split normally happens inside the house far from the frozen section. The ice outside blocks the pipe so there's enclosed water between the ice and the valves inside the house. As freezing continues outside the house that enclosed space gets smaller and smaller, water pressure builds and builds until the weakest point fails, normally some place inside the house. The tip of opening a tap a little can keep the ice blockage from forming...sometimes. But the open tap will almost always stop a pipe from busting even if ice does block the pipe because it relieves the water pressure. I know from past experience most people will never be convince of this, but it can be Googled if interested. And it is interesting.

Water expands about 10% in volume when frozen. So when a 15'x15' pond freezes some people think the ice would cause the pond to expand to 16.5'x16.5'. If that was true even most liner ponds would fail. But as the water freezes there's plenty of spaces for water to push out. So the top of the ice end up being higher than the water level was. Same thing happens with mortar, as the ice forms water is just pushed out of the way. There can be some pushing around of loose rocks as the ice cap grows and/or floats higher. Normally the ice slips past the rock, or mortared side. But it is possible for places where a chunk gets pushed out of place. So for say 12" thick ice the upward expansion would be about 1" in theory. But because ice is initially thin and weak there's no problem with rocks and mortared side to resist the upward movement and often the edges and are the warmest and weakest point. So generally a 12" thick ice cap may push places maybe 1/2" in places. As the ice melts these chunks would normally just sink back into place.

Mortared rock doesn't generally contain enclosed, water tight spaces, so generally freezing isn't a problem. Just like concrete sidwalks, steps, etc., which are common in freezing climates, don't fall apart every year. When concrete does fail in those climates freezing is often blamed instead of the real cause such as rusting rebar or poorly installed concrete. I've seen more decomposing concrete here in Phoenix than I ever saw in Upstate NY because here people pour the concrete when it's too hot and so it falls apart over the years.

Because it's virtually impossible to convince people of this I normally don't bother. Instead I show them how to make rocks out of mortar like these cap stones. These hang over the side and if the owner wants they can be flipped out of the pond in the fall. Not needed, but it makes some people feel better.

 

[Craig58]

Waterbug,

I respect you a lot and know you have lots of experience in this. And maybe we'll have to agree to disagree. But i haven't repaired a split pipe due to freezing in my house or any of my rentals over the years inside yet! I agree about trapped water entirely and sometimes a dripping line can prevent it.

You are totally right about the expansion of the pond ice though. There is space available for the expansion in many cases. But maybe I don't understand your design totally. I assume the liner is placed first, then the mortared rocks are on top of that. That should cause very small spaces between the liner and mortar. I'm sure those spaces are not water tight and that some water will seep in. While it might not happen right away, I can't imagine that you wouldn't wind up seeing the mositure trapped in some of these tiny spaces in here and freezing. Over a few years, I'm sure that would eventually takes it's toll on the mortar, (at least the stuff in the freeze zone near the top). Mortar itself is not waterproof and will soak in water which can also get trapped and freeze. Almost microscopic but over time it will take its toll on the mortar.

I could never recomend that to anyone in our area and feel confident about it. In the more temperate climes it might be fine for 20-30 yrs.

Your concern about pouring concrete when it is too hot is very valid. The moisture allows a chemical reaction to happen in the concrete/mortar and if that isn't allowed to happen, (drys too fast, or to dry of a mix to start with), you wind up with very brittle concrete. In the summer here we often will cover it with plastic and water it daily for a few days sometimes. I'm sure "good" contractors probably do the same in your area. Unfortunately, its hard to find the good ones!!!

Craig

 

[Waterbug]

I assume the liner is placed first, then the mortared rocks are on top of that.

Yes.

That should cause very small spaces between the liner and mortar.

Definitely. From the freeze thaw perspective I would even say the spaces are large. Lots of large air bubbles between the mortar and liner can be seen when I've torn down such a pond. So plenty of voids for water and ice to get into.

I'm sure those spaces are not water tight and that some water will seep in.

Correct.

While it might not happen right away, I can't imagine that you wouldn't wind up seeing the mositure trapped in some of these tiny spaces in here and freezing.]

Absolutely true. I don't see how it would be possible to ever not be true.

Over a few years, I'm sure that would eventually takes it's toll on the mortar, (at least the stuff in the freeze zone near the top). Mortar itself is not waterproof and will soak in water which can also get trapped and freeze. Almost microscopic but over time it will take its toll on the mortar.

Water can take a toll on mortar reducing life span to a few years if acid enough. In a normal pond water can reduce life span to the 20, 30, 50 year range depending on the thickness and other factors like a muck layer that would be acidic.

will soak in water which can also get trapped and freeze.

That's the misconception, trapped. Freezing is only an issue in enclosed spaces. If water can soak into a void under no pressure...it can also soak out, especially when under pressure. Again, concrete sidewalks in winter before a freeze may have many (billions) of small openings completely full of water. As the ice forms molecule by molecule and pressure increases and liquid water molecules are push out of the voids. The result is an opening completely filled with ice, no pressure, and no breakage.

Anyone can put a chunk of mortar or concrete into a container of water and place it into their freezer. No damage. Repeat as often as desired, no damage.

Where there would be a problem is if a cement vessel was formed, filled with water and frozen. Flower pots for example can break if full of wet soil and freezes.

Certainly I can see that in billions of applications of cement in freezing climates around the world that there must be cases where ice formed in the perfect storm that there's been damage. Concrete foundations in many areas are submerged in water (like NY where I grew up the water table was at ground level in winter) and freeze without damage for decades (my boy hood home is 101 years old and still has no problem). Thousands of gunite pools in freezing climates submerged in water (from the outside) seem to be OK. Many, many examples.

I could never recomend that to anyone in our area and feel confident about it. In the more temperate climes it might be fine for 20-30 yrs.

A very good idea imo to never recommend things you don't feel comfortable with. However, the more you learn, the more comfortable you can become in engineering solutions. It's been my experience in both software, pond and other stuff that those jobs pay way better. So for me it's been worth the research.

Back years ago I had many discussions in pond forums describing options in freezing climates. It was fine, but I doubt I ever changed anyone's mind on the subject. It's just one of those things that sticks in most people's minds even if they're surrounded by frozen cement products in and around the home, at work, at stores, everywhere. So these days I rarely even talk about making rocks or mortared rock because it doesn't really help anyone. Those interested enough can certainly find enough info on the subject. Not exactly like I'm the first person to ever say cement can last in freezing submerged conditions.

 

[waynefrcan]

NO one and I mean NO one mortars or cements the rocks in the bottom or sides of a pond, in my side of the world. Edge stones yes, waterfalls yes only.

I would think also that if it cracks and shifts it might damage the liner as well.

Not for me sorry.

 

[JohnHuff]

I'm a long time pond keeper and a recent aquarium tank owner. My pond is mostly bare but almost all aquarium tanks have gravel in them. The reason tanks have gravel in them is for the bacteria and because of the relatively large amount of gravel in the tanks, tanks are also able to hold a relatively larger fish load. But then, tanks are much easier to vacuum. I vacuum my tank about once a week, but my pond only 1-2x a year.

So now, I've come to the opinion that perhaps small containers of underwater rockeries are doable and not that bad. Perhaps a couple of those flat under the bed plastic containers filled with rocks along the edges of the pond which would be easy to vacuum out but would provide a much larger surface area that the bare liner it would cover.