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by Robert (Bob) Fenner

Trouble calculating my pond volume      4/27/17
I am trying to figure out the volume of my irregular shaped pond. I got 3 different measurements on it. One for the shallow end (2'Lx5'Wx0.1'D), my second deepest part (5'Lx8'Wx1.6'D), and my deepest part of the pond (3'Lx
6.9'Wx3'D). What is the volume of my pond in USA gallons?
<Mmm; multiply all three measurements... add for cubic feet, multiply this by 7.5 (gal.s/cu ft.), done>
I am having trouble calculating these measurements due to a math disability. Can you help me with this one? Thank you.
<Otherwise, time how long it takes to fill a given volume container (like a five gallon plastic bucket) and measure the time it takes to fill the basin. Bob Fenner>

Small Pond Goldfish Pond Survival      9/25/14
I have a 765 gallon, irregular shaped, sunken pond. It is a 45 mil. EPDM liner pond. It is a few weeks over 1 year old. It has a pH of about 8. It has a uv, a fountain, and a submersible filter with a water pump of about 625 gph. 2 of my adult fish died about 2 days ago. A calico Shubunkin goldfish and a big white comet. They got gill damage. They got it from being cooped up with 11 other goldfish. They were in a way too small 50 gallon tank, with no filter or aeration. They stayed in there for a day and overnight. My fault entirely. I should have known better. I got 2 new replacement fish for them today. A little yellow comet and another redheaded Shubunkin. They are both about 2 inches long. I live in the Arizona desert. Will the 2 new fish have time to build up their size and reserves before it gets too cold?
<Should do, but depends on how mild your autumns are and how cold it actually gets in your winters. Remember, Goldfish can feed and metabolise down to 10-12 degrees C, using low protein foods such as wheat germ, but below that they shouldn't be fed anything at all until springtime rolls round and it warms up above 10-12 C. Very small Goldfish may do better overwintered indoors, and your 50 gallon tank should be ample for that.
Mortality of yearling Goldfish can be quite high in cold climates where ice forms over the pond, but Arizona might well be mild enough for yours to do okay.>
Thank you.
<Welcome, Neale (in the UK). Have cc'ed RMF to add a more Southwestern USA perspective.>
<<IF the pond is large enough, deep enough, protected by structure from much influence of (weather) elements... to not vacillate much thermally (see WWM re as always); the biota should be fine here. RMF>>
Re: Small Pond Goldfish Pond Survival     
Thank you Neale! :)
<Most welcome.>

Is the total # of gallons for my pond correct?   7/9/14
Pond Information
Date made
Current Water type
ph 8-9
Gph 625
Type= Flexible EPDM .45 mil. liner, sunken
Style= informal
Location= backyard
Site information= The site for my pond was a floodplain. It is mostly hot and dry, floods during monsoon season. This flooding was taken into account when pond was built. Cement wall was installed to prevent flood waters from getting into the pond. The land is low-lying, with hard, gritty, sandy, soil full of gravel.
Shape= irregular
Depth= shallow
Size= medium
767 gallons
14.1'long x 11.3 wide x 3.3' deep= total area dimensions
Underlayment= 25' L x 20' W
EPDM 45 mil. Flexible liner= 25' L x 20' W
Soft sand= 2" deep in bottom of deep area, deep end, middle, and shallow end.
No drain pipe necessary unless ground water is present during digging. No drain pipe was necessary for this pond.
Cement wall around pond dimensions= 615" L x 6" W x 4" H x 4" Deep (51.3' L x 4" W x 4" D)
Main pond dimensions (where the water is)= 12.5' L x 9' W x 3' deep
The pond dimensions divided into 3 different sections:
Dimensions for Shallow End
Filter box 1.5' L x 1.5' W x 11"D, total gallons= 2
Top part of shallow end 3.5' L x 4.10' W x 5" D, total gallons= 54
Total gallons for shallow end = 56
Dimensions for middle of pond
deep area 3' L × 3' W x 1.6' D, total gallons= 108
Top layer before deep area 5.8' Lx 6.4' W x 8" D, total gallons= 223
total gallons for middle of pond= 331
Deep End Dimensions
3.9' L x 8.11' W x 1.6' D, total gallons for end of pond= 380
Total pond gallons should be 767.
Is this total number of gallons correct?
<I do think you're close... There's about 7.5 gals/cubic foot, 231 cubic inches per gallon... Another way of determining volume; should you find your system empty at some point: Practice filling a known volume (e.g. a five gallon plastic bucket) timed with a watch/device w/ a second hand/counter... then with the hose turned up the same (all the way), measure how long it takes to fill the pond... Divide by the number of second equivalents it took to fill the bucket, multiply times five. Bob Fenner>
re: Is the total # of gallons for my pond correct?   7/9/14

Thank you Bob.
<Welcome Cam>

GF, pond size       1/1/14
Hello. My name is Joshua and I am 15 years old. First off, I would like to thank the crew for all the help I've received over the years.
Between saltwater & freshwater, I've really learned a lot from your website and it has been my "go to" website whenever I need a question answered, or for a recommendation to others. But anyway, on to the question! I've been a long time reader on WWM (about three years), and I'm writing in today because I have a few questions regarding Goldfish. I've noticed there seems to be quite a debate on the topic of Goldfish pond sizes. Websites such as Aquascapeinc.com and Watergarden.org (I will place links to the articles at the end of the email) as well as several videos on YouTube state that as long as the pond is over 10/20 gallons that any type of Goldfish can be added.
<No... foolish statement
... First off, the "size" as in volume is only one indication/limiter... the shape, and location... relative to structure as well as ambient weather are important/critical as well. Secondly, "it depends" on gear in use... There ARE some countervailing heaters, filters, circulators, aerators... that can be used to crowd goldfishes, but some/most varieties get too large for a system of only a few tens of gallons>
 They also say that Goldfish can limit their size to the size of their environment.
I suggest these folks try living in a closet for a few weeks>
Now, however, your website states that stunting their size can cause a variety of physical deformities, as well a shortened lifespan. My question is, is there any truth to what they say? Can Goldfish really live happily in such small quarters for long periods of time?
<Ah yes>
 And would you consider the 20 gallon rule a good one?
<Ah no>
Thanks for taking the time to answer this, it's just a question that's bugged me for quite some time.  ~Joshua.  
http://watergarden.com/tub/index.html  Ps. I've probably read all the Goldfish pond articles and FAQs 10 or more times now. :)
<Cheers, Bob Fenner>
Thanks for the fast reply!
One last question: can Fantails be kept outdoors year-round?
<... if the system is stable enough, doesn't vacillate temp. wise too much... yes. BobF>

How Many Gallons Would I Have... Pond project, reading     6/27/13
I am considering building a goldfish pond. I live in the Arizona desert.
<A nice project and fine place to have it... Do provide protection from the sun... place near building/structure, build shading....>
I plan to make the pond 10 ft. in diameter by 3 ft. deep. Plan to use a Butyl liner with a fine, soft sand as an underlayment. Underlayment will be 1-2 inches deep. No plants planned. I am not very good with plants. How many US liquid gallons will this pond setup hold?
<A few ways you can find out... mathematically... there's about 7.5 gallons per cubic foot... and the area of a circle is pi R squared... times three feet of depth... R equals 5 (ft.), times itself is 25, times pi... times three feet... times 7.5 (cu. ft./g)... about 1750 gallons... More accurate likely to practice/measure filling a known volume, like a 5 gal. "pickle bucket... then filling the basin, timing how long this takes... This is all gone over on WWM if you'd search>
I will be adding fish. Do not know how many because I do not know how many gallons I have to work with yet.
 Will be adding a pump with a filter too. Do not know which one to get yet because I do not know how many gallons I have to work with yet.
<You've got a bit of reading to do... much better, and less headaches and cost later. Start here:
and read down. You're welcome. Bob Fenner>
How Many Gallons 2... ? More re pond vol. measurement     6/27/13

Sorry. I neglected to mention I have a math disability. This makes doing math difficult to impossible for me.
I found a simple calculation elsewhere that could also tell how many gallons I have in my to be round pond. It goes like this:
length X width X depth X 5.9 gallons
<... what? In feet? No... see the prev. email... there are about 7.5 gal.s per cubic foot>
In this equation the length and width are the same.
If the pond is not round, the equation goes like this:
length X width X depth X 7.5 gallons
Using these equations, would I get the correct number of gallons for my planned pond?
Butterfly Koi     6/27/13

I live in the Arizona desert. I have been thinking about ponds for butterfly Koi. It will be 1,100 gallons for two of them. Let me know the correct number of gallons for 2 if this is not right. How deep should I dig my pond for 2 butterfly Koi? It is going to be a round pond. What diameter should it be for 2 butterfly Koi?
Thank you.
<Please keep reading where I referred you to this AM. B>

Re: Indoor housing Koi    7/20/12
Thank you for the insight and the helpful information. We have found the new house, and it actually has a water fountain at the side yard. It is a courtyard that sees little disturbance and is well-sheltered from both the elements and from most of the outstanding predators, though I don't doubt a starving coyote or neighborhood wandering cat could jump the fence. The fountain is not currently in use, and, if possible, I was thinking of converting it into a small pond, with only a fraction of the Koi, and house the remaining Koi with my friend, who is willing to take on overflow. There are many issues, of course, with this, not knowing the full history of the fountain, the fact that it is or was chlorinated before the previous owners left, and the issue of materials.
The chlorine pump, if there is one, will be turned off or disconnected entirely, the water swapped out and replaced after a good rubdown with bleach, if necessary, but for the most part, a good scrub should do fine.
It is full of algae, which may even have grown in the weeks since the fountain was turned off. The water available has a good parameter set, gH tested at about 160-180, and pH was solid between 7.0 and 7.5. So, since the water is about the same as the water at my current home, I expect the patterns of ebb and flow to be similar, with differences attributable to external influence.
The fountain itself is 42" x 64" x 14".

From the absolute top of the fountain to the water surface, there is about 6" of free space, but when taking the height measurement, I excluded this space, so the actual water level was 14" from the bottom.. I calculated the volume, and found that filled to capacity, it would hold approximately 162 gallons. Therefore, I intend to purchase an external canister filter capable of operating for about 175 gallons, and will add some activated carbon harboring bacterial colonies from my existing filters to the filter media, if possible, will likely add a good amount of the water from my cycled tanks, and will perhaps purchase several feeder goldfish to create ammonia about a week after initial setup, then let the cycle run for about 3 weeks, keeping a close eye on the water parameters.
<Just use a bit of food. No fish>
 If the cycle is in adequate form by then, I will start adding my Koi.
However, the biggest obstacle I can see is the fountain itself.
The fountain is rectangular, and lined with ceramic tiles, and the bottom of the fountain seems to be concrete. My concern here, of course, is this material. The house, and the fountain, are not new. They have been there several years, which may or may not have  been enough time for either anything harmful to have long-since leeched out of the material, or for a sealing material to wear off and harmful chemicals start to leech into the water. The fountain has raised edges with ledges, and runoff does not breach the fountain. So, given all this, is there a liquid Master Test Kit that tests for lye and other such harmful chemicals that you could perhaps expect to leech from concrete?
<There is very likely VERY little of this at this time>
 Alternatively, is there a product I can use to easily and effectively seal the material to prevent the possibility of leeching?
Perhaps most importantly, can I effectively convert this fountain into a small pond with one or two Koi, or is this an ultimately hopeless venture?
If this is just impossible, then I will simply turn over the Koi to the friend of mine with a well-established Koi pond, and instead opt for a somewhat larger than "desktop" aquarium for my crayfish. Thank you.
<... best for you to keep planning on building a real pond in future. BobF>
December 21, 2011 1:15 PM
To: Crew@WetWebMedia.com
Subject: Indoor housing Koi

Before I begin, I would like to tell you that the arrangement is only temporary, and I am very well aware that Koi cannot be expected to permanently thrive in an indoor aquarium. However, for the time being, the Koi are small and immature enough that the current conditions in which they are being kept are sufficient. They receive a highly varied diet of Koi pond sticks, freeze-dried foods, the occasional live food, frozen food, and some fruits and veggies. They greet fruits and veggies I attempt to introduce with tentative caution, but if left alone for a while, eventually come to understand that they are food.
<Mmm, a good grade of pellets alone is fine>
They are currently housed in a 40 gallon tank with a filter that was made for a 75 gallon tank, in an attempt to assure adequate filtration during their stay. There are six Koi, most between 1-3" and one at least 4".
However, they show no signs of stress or agitation, and even get along with my dog when she presses her nose against the glass.
Now then, then only reason I opted to keep the fish indoors is because I live in an area where there is a nature reserve pretty much in my backyard.
Coyotes and red-tails are a constant, and the coyotes have even learned to imitate dogs barking to lure out pets. I have yet to see a raccoon in the neighborhood, but I am sure they are here.
<Raccoons are tremendous Pondfish eaters; very hard to keep out>
The soil quality of the area is extremely dense, with about 2-3" of topsoil, over a good 6" of clay. There are also very few pond building specialists with the capacity to help me design a pond with the depth and form necessary to keep these predators away.
<I will help you from afar if you'd like>
We may also move within a year. I perform frequent water changes on the tank, usually massive, and done slowly and with minimal invasiveness to minimize the stress to the fish.
<Do these weekly>
The water is cloudy, but it is a problem with the food I've been feeding them rapidly dissolving into the water, and by doing the more massive water changes, I am able to rapidly fix it. I plan to switch them over to Hikari Growth Saki, if I can get my hands on it, or the readily available steeple diets from Hikari.
<Both are excellent, as is the Spectrum pellet line>
The water I fill the tank from is hard with a solid pH of about 7.4 to 8, and the water is salted appropriately.
<No salt adding necessary or suggested>
I live is Southern California. Specifically, I live in Stevenson Ranch, CA. Is there anyone, or any place that I can turn to nearby that will help me to plan out an adequate pond or environment for my Koi?
<Here... as in WWM, and myself>
I myself am on a but of a budget, but am willing to devote any resource necessary to maintain the health and safety of my fish. A neighbor of mine has a pond, although it is not professionally constructed and vulnerable to predators, where, if the need were absolute, they have offered to temporarily house my Koi, should they outgrow the tank before an adequate pond could be constructed, or should we move. Any help, and an approximate estimate of how long it may take the fish to outgrow their current home is welcome.
<Likely w/in a year... I would be very skimpy re feeding>
The fish are not mature, and I am not even able to determine their genders, but they are healthy and active, and two have even become my wonderful provocateur fish.
<Ah good. Do take your time, peruse the Pond Subweb here:
From the top down. Cheers, Bob Fenner>

Water Quality Problems with a Reflection Pool. Ftn. design, maint.  6/27/12
Hi Bob,
<Hello Bruce>
I live in Ottawa, Ontario in a condo with a large reflection pool in the courtyard.  The pool measures about 25' by 50' and there is room for the water level to be 7 inches.
<Ugghh! Hard to keep such shallow systems chemically stable... clean>
 Right now, however, there is a layer of small pebbles on the bottom so there is only about 4 - 5 inches of water.
<Yikes! Even worse!>

  The pebbles have trapped dirt over the years and they hold a bevy of sludge and other impurities.  The pool originally had new water added continuously with the old water going down the drain.

 When the city started to charge for water, the pool water was recirculated to avoid waste.  The pool is in the sun for most of the day. 
<Good gosh... do you have numerous ducks as well?>

We have a fountain in the middle of the pool that gives a nice effect but does little to circulate the water.  We have added a second pump to push water around the perimeter and we place chlorine pucks in front of it. 
<... one approach. You need to have... measure, maintain "conditioner" (see the pool folks, biz); and monitor pH and alkalinity as well>

 This has had little effect other than right in front of the outlet.  Needless to say, with the hot weather comes algae.  It is only June and we have had to empty the pool and start again.
The water does not circulate and the chlorine is not sufficient to stop any algae build up.

We are contemplating some changes to improve the water circulation but are uncertain of the effectiveness of each.  Both options include eliminating the pebbles in the pool.
<Yes I would... or at least mortar them with just half or less of their faces exposed... for ease of vacuuming, cleaning>

  The first option would be to replace the liner with one that would allow a water depth of 9 inches as we are told that this would allow for the introduction of plants that would help to purify the water.
<Mmm, not worthwhile; no. This is still way too shallow>
  This is somewhat problematic as we are told the plants would have to be stored somewhere over the winter.  The second option would be to increase the circulation with either a 6-7 inch depth or a 9 inch depth if necessary and introduce a chlorination system of some sort to keep the water clear.  Under each option, key to success, we believe, is to increase significantly the circulation of water in the pool.
<These would help...
We were wondering if you could provide any advice on the relative effectiveness of plants vs. chlorine in keeping the pool water clear and on an appropriate circulation system (capacity and type) to keep the water moving and clear.  Would either scenario require raising the depth from 6-7 inches to 9 inches?
<Won't help much... I wouldn't advise it. IF the area around the feature could be built up... above grade... to eighteen or more inches... this basin could be made biological>
 How effective would reducing the size of the pool to about 25' by 30' be in providing an effective solution.
<A percentage by volume...>
We would greatly appreciate any advice you might be able to give.
Thank you.
Bruce Irving
<Mmm, there are a few moda chemically to consider other than the current chlorine/pool/spa... Some are toxic to surrounding landscape... so if there's much splash, spray from the central jet... I might well propose abandoning this water feature altogether (it can't be made either serviceable or functional really... and replacing it with more garden... art... benches, a contemplation area. Bob Fenner>

Will my 'pond' support my goldfish?  8/1/10
I have 2 beautiful goldfish, a common (male) and a Sarasa comet (female).
My comet is around the 14cm mark (inc. tail) and my common is around 11cm (inc. tail). They are residing in a 40 gallon pond.
<Mmm, too small a volume to be "very" or sufficiently stable... even in a tropical latitude>
I have an old (yet working fine) sponge filter and pump in with them, in addition to 3 goldfish-mangled plants (2 Vallisnerias and 1 milfoil.)
I do weekly water changes of 60%.
After reading many, many different websites each with different opinions on the amount of litres suitable for an adult single-tailed goldfish really is, I am very confused and unsure.
February this year, (3 days after moving into the 40 gallon) from a 10 gallon) they spawned for the first and only time. I was wondering if they spawned again if it would be an indication of happiness in their current home?
<Is indicative...>
I am unsure as to whether or not this is relevant as I have been able to find hardly any information on this subject, my Sarasa comet is a linear-scaled goldfish ( very beautiful!). Will she grow any larger than usual?
<Yes... all goldfish are the same cross... akin to domestic dogs, cats... Can, will grow to more than a foot in length given propitious circumstances>
So, in conclusion, I was wondering if 40 gallons will suffice for these two fish, and if not how long do I have (if not already) before they will be impacted upon and if there is anything additional I can do to prevent this?
<Are already being slowed in their growth here... Need at least a hundred gallons or so to "realize their potential">
Thank you sincerely, Amy.
<Welcome. Bob Fenner> 

Pond construction, shape... liner use 6/6/09
I'm building a raised formal geometric shaped Koi pond.
<Mmm, beware of "tight corners"... for your fishes (Nishikigoi "panic" at times when "caught in corners), as well as circulation and all it entails reasons>
Concrete block walls with sand/cement hard bottom and liner. Questions;
#1....in regards to the liner, is it possible to cut it into sections, align them (with overlap) and "weld" or bond them together to make a form-fitted liner in order to avoid unsightly wrinkles and folds?
<Yes it is possible. Do be sure to check re the type of material/solvent for welding (we used tetra hydro furane for PVC for instance)>
I'm a fairly "handy" guy and I'm not afraid to try anything at least once!
#2.... I plan to install a VERY heavy cast concrete statue (fountain) in the middle of the pond, with its base just below water level, resting on an "island" of concrete blocks (4 ft pond depth). My thoughts are these;
poured concrete footer, an underlayment, liner,
<Mmm, the underlayment first... perhaps a piece of carpet... then the concrete...>
then concrete block "island" mortared above, and of course the statue on top. Obviously an enormous amount of weight. Any advice here? Thank you in advance.
<Enjoy the process. Bob Fenner>

Pond... plumbing, shape design...  10/3/07 Hi folks, I respect your request for avoiding questions that the user could find in the FAQ or with Google. I found your site with a Google search and I don't see my question answered anywhere yet so hopefully, I am not creating undue burdens here, and thanks very much for setting up the space to ask. <Welcome> I am now facing taking over someone else's project at mid point. The contractor apparently had a shady side and is now in jail. <Yikes!> Looks like promises were made and not kept about what was ordered, etc. I was looking at the hole he left last night and I am researching all I remember from my own pond building and pond maintenance days and my landscape design classes to see what I would need to pull this off. I used to work for a relatively high end pond and water building firm in the DC area. I dug holes, moved rocks, ran equipment and most especially did lots of maintenance on filters and ponds. I never felt responsible for designing the whole thing, engineering the plumbing although I have certainly fixed broken pipes, valves and pumps. And I have some awareness of waterfalls, stream beds, construction and (gulp) leaks. I have also installed some small features for friend's and I usually build my own filters to sit in the pond. This project will be one, or two steps beyond what I have already done. And, I haven't been in the business for over ten years so I am internet researching to job my memory of what we used to do. <Okay> The size of the pond is roughly 15 x 30 feet. On the deep end it looks to be over 6 or 7 feet. <Good-sized... what do the folks in charge "want it to do?"> The pond is roughly kidney shaped and it is already dug out. The contractor left a layer of plastic sheeting over it like a liner, I don't know why. The homeowner said the contractor said he did it to dry out the ground (?) <?> Is this a technique that sounds familiar to anyone? <No> First step would be to remove it as I am going with my experience installing the underlayment and the EPDM liner. <Good> The first thing I notice is there is no work started yet on the plumbing, no skimmer, no trenches or pipes, no bottom drain. So my first question is, common sense from a maintenance background is to install the bottom drain. There is no hole or trench dug for a bottom drain so I have to take care of that too. But I need to research how that works. I have seen it working but I can't remember "how" it runs. I am a little confused with all the different installations I was a part of and I hope I am not mixing one idea with another? I have seen skimmer boxes with the pump inside them. <Mmm, really?> In that case water is sucked into the skimmer and pushed through the pipe up to the bio filter which doubles as a waterfall top edge. <Have seen these...> In other systems the filter or filters are vortex, bead or other external variety, usually with high nitrate producing Koi, are outside the system and isolated a bit to take the pump sounds away from the pond design. I think this would be over kill on this design for what the customer wants. <Good units... pricey to acquire and operate, but work> I also know there is value in adding a waterfall pump and having a regular circulation pump. This allows energy savings when you want to keep your system filtered and healthy but not pay the electric bill or possibly generate noise all the time with the full force of the waterfall. It also allows for maintenance and adjustment to the waterfall without hurting the pond system. <Well-stated> That's what I know. What I don't know is about how to set up a bottom drain and valve it to the flow of the skimmer? <Mmm, can be done through the membrane (with flanges) or inside... via trenching in both... the main drain plumbed to the skimmer directly if one wants... with the second/behind hole going up/out of the system to the pump intake... but I encourage you to have at least two intakes... if you want a skimmer (or two), plumb these AND the main drain separately out, up to the pump...> If I take on this design, I am thinking that the pump needs to pull water from both the bottom drain line and also the skimmer. <Yes, this is best> If true than the design with a push pump in the skimmer would not work. <Correct... and I am NOT a fan of submersible pumps...> Is this true? Therefore if I used a bottom drain I would look at designs with the pump in the biofalls or free standing outside or behind the waterfalls. I would need one of these designs to achieve puling the water up the button drain and the skimmer, yes? <Yes> And if I am on the right track there, then I will need a valve to adjust the rate of intake between the skimmer and the bottom drain, Yes? <Correct> If I read correctly, there is a reason to completely shut off the skimmer if necessary to feed the fish or for skimmer maintenance and if I designed it correctly I could just valve to the bottom drain 100% with no worries. Yes? <Yes> Can someone please refresh my memory as to what is the usual percentage of flow between bottom drain and slimmer to the system? <Mmm, less to the skimmer/s... ten-twenty percent or so; the remaining from the main> Assuming that in large part this is something you observe once it is running but there should also be a rule of thumb here. <Yes> If I read on line articles right and compare that to the ponds I have installed in the past, I believe you don't want the water fall or pond return flow too near the bottom drain, for achieving good circulation mainly. But that is how the contractor has set it up so is this something I should really consider doing differently or is it really going to be a problem? <Not likely a problem> I should mention that although I see the wisdom of a bottom drain, if it turns out to be out of the homeowners budget or not completely necessary, I want to consider the design without this feature. I assume this takes me to the simplest solution mentioned earlier of putting a pump in a skimmer box and running a single line to a biofalls. Yes? <... not if it were my design, no. Much to be related here... the best engineering involves a "passive" system of plumbing that conducts water NOT from the bottom, but maybe 3 or 4/5s the way down... this water recirculated... and a bottom "drain" in addition to simply dump the "bad water" from the bottom itself...> The other question I have, also important, is about pond construction. This is Denver. I am writing this in early October so I may have a month left before the ground gets too solid. Or, I could have two months let, you never know around here. I am sure there must me what we called frost heave back in Virginia, here in Denver. YOU have to build with a mind to the changes in the soil when it freezes and thaws again. <Yes> With that in mind I want to ask about the technique that I remember using and ask for some feedback to see if what I am thinking of doing, makes sense to an expert? <Sloping sides, good landscape drainage, perhaps a sand bed arrangement around the basin, not leaving the system empty during freezing weather> I am used to digging more or less vertical walls in the dirt and taking the top 18" down for setting one or two cinder blocks, depending on the strength of the surrounding soil. We laid the cinder blocks on the side and filled the holes with tightly packed dirt. Then we rammed pieces of rebar into each hole. We built some very nice high end designs this way and while it stabilized the bank, or seemed to in the Virginia clay, it also was a way to provide a stable base for large heavy rocks that could be put next to or on, an edge. <Sounds very good> I see lots of "how to's" on the web about building cinder block walls form the bottom of the pond, but none using the techniques I am remembering. <I am unfamiliar with this as well> The contractor left long sloping edges that I don't like very much. They slope nearly 45 degrees around the shallow end. <Mmm, yes... not good for maintenance, but better to avoid having the basin crushed, pop-out during coldest weather> It seems more natural to my mind to cut the edges more to a vertical angle, possibly leaving ledges (yes knowing about predators and ledges). Is there any reason a design would have such largely sloping edges that I am not aware of? It also seems more potentially stable to make a proper wall at the start. And that means pretty much vertical with soft rounding on the bottom edges, more art than science but then, I have been there and done that before. <As stated> Thanks much folks. I know I am asking a lot but I hope my questions have provided enough clarity for answers. I would recap this into wall constructions with cinder blocks on the top layer only and bottom drains and system choices for pond mechanics. If you post my question and your response please omit my phone number and email. Thanks. David Groover <Am unfortunately going to be out of Net reach for a couple of weeks soon... Bob Fenner>

Pond Overwintering, not reading   8/19/06 Ok well I live in  Pennsylvania where it is pretty cold and the pond will freeze. How deep does it  have to be. <Mmm... depends on what you intend to keep in it, where it's located relative to "structure", whether you intend to employ countervailing strategies to prevent it freezing over/all the way to the bottom... 4 to 6 feet likely...> Also is there any specific brand of food I should feed them or what  should I feed them to get their fat up for the winter. <Please read here: http://www.wetwebmedia.com/PondSubWebIndex/pdmaintwint.htm and the linked files above... Bob Fenner>

Pondfishes in the GWN  3/3/06 Hello I am thinking of setting up a small outdoor pond - 180 gallons - which contains no heater and a basic filter. <... likely too unstable at this volume...> I am located in Nanaimo, British Columbia, Canada. I have a couple of questions: What type of fish would you suggest? Can they survive the winter? <Perhaps some of the local life...> What happens if the water freezes in the pond? <If all the way down, fishicles... See WWM re ponds please: http://wetwebmedia.com/PondSubWebIndex/Pond%20Sub%20Web.htm See all those blue file names? They're links... Bob Fenner> Thank you Pat

Pond article Corr.  1/20/06 Your article was most informative.  However, please change the spelling of the word "irregardless,"  found in the first sentence of the section entitled, "Shape and Size."  There is no such word, it should be regardless. <Thank you for this. BobF> <<And looking on Google... there's a few pages of others...>> Pond depth, poor English 10/13/05 I am digging a small backyard pool (wildlife area) about 15 feet long &4 to5 feet wide .I want to put a few medium sized fish in it .I started digging it two feet deep .is this deep enough or would 18" be enough? Don <There are economic, practical and legal inputs here... Please read: http://wetwebmedia.com/PondSubWebIndex/pddessize.htm and the linked files above re. Bob Fenner>

Tropical Ponds Bob, I see that you answer all the questions regarding ponds on the WWM.com website, I apologies for the length of this email, but figured better to send all the details. <Good> I have read through the pond section at WWM.com and found it to be very informative, however I have been unable to find anything on tropical ponds. I live in Thailand and the availability of pumps, accessories etc for pond construction is very limited and for that reason most of the construction will be DIY. I have a number of questions that I have been unable to find the answers to that I hope you can help me with. Background details, (The Plan!). Construction; liner with reinforced concrete and then Thoroseal, (or equivalent if I can find it). Pond shape; roughly pear, 5mt long x 3mt > 1.5mt, 1mt high waterfall at the 3mt width end. Plumbing ; 4 x 2" outlets, (with debris traps), set in the bottom of the pond going into a pre-filter using round stones or rough plastic balls. The inlet to the pre-filter would be at the same level as the 4 outlets. From this the pump suction would be approximately 3" below the water level of the pond. Pump discharge is 10.5 Lt per minute, which will go into a filter. The filter will be 3 stage type using; settling, plastic hair curler type tubes and then into to the bio-filter chamber and then into the top pool of the waterfall. I will also include drains/by-passes and back-wash piping for cleaning in the final design. <Does sound like you've been investigating. Sounds good thus far> The Questions * Most articles recommend a water depth of 3ft, I found 1 forum article regarding warm water ponds which said this type should only be 18" deep. What would be the recommendation for a pond here in Thailand, average temperature 28'C, 83'F? <I would make the pond deeper... more stable all the way around, should you find that you want to keep fishes that appreciate smaller shifts in temperature, dissolved oxygen, pH... Easier to maintain if deeper as well> * The pond will not be shaded, should I use a UV filter? <If suspended algal over-growth is an issue, yes> * Can you recommend any books, web sites etc on the subject of tropical ponds, with sections on the type of plants and fish species that can be mixed etc. <There are many... some in English by Tropical Fish Hobbyist Publications, some in Japanese. None are definitive IMO... I encourage you to try getting, reading what you can from a larger library, but as importantly to seek out others (maybe a pond society there) who have built similar systems in your locale, the input of concrete contractors, landscapers... and the input you can garner from the Internet (on various bulletin boards, chatforums) re ponds. You have a good grasp of what this project is about and will do fine investigating, keeping good notes, sorting out your options.> Many thanks in advance for any advice you can offer. Regards Neil Sandilands <Bob Fenner>
Re: Tropical Ponds
Bob, Many Thanks for your prompt reply, I apologize that mine was somewhat slower, but my work location sometimes has problems with internet connections.  <I understand... completely> I will definitely go deeper as recommended and try and find some books/contacts in my area, I'll see what happens regarding UV. I anticipate around 6 months for construction, (due to work schedule), hopefully all will run smoothly. Thanks again. Regards Neil <Ah, a grand adventure. I was/am involved in a couple of "authentic" Japanese ponds that started construction before my joining and are still "being built" more than three decades later... these "things" take time... Enjoy the process my friend. Bob Fenner>

Aquatic Gardens

Ponds, Streams, Waterfalls & Fountains:
Volume 1. Design & Construction
Volume 2. Maintenance, Stocking, Examples

V. 1 Print and eBook on Amazon
V. 2 Print and eBook on Amazon

by Robert (Bob) Fenner
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