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/Aquatic Gardens, Design, Construction & Maintenance

Example Systems: the Provence's Pond

By Bob Fenner

Overview of the bulk of Provence Pond

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

The Provence's pond is easily an "A" in anybody's water feature school; early on, Ray and Anita, had a very good idea of what they wanted. "We've done the designs and built our last three homes, including the landscapes", admits Ray. "When we first saw this lot with it's expansive chaparral vista out the back, we just knew we would end up with a large water feature". Anita adds, "We always longed for a setting like this, atop an open hillside with lots of room", "We wanted to arrange plantings and a pool of water to attract and enjoy the native wildlife".

Over the course of time of building the house and getting acquainted with pond possibilities in Southern California, the Provence's decided on an expansive pond that would accommodate a large aquatic plant collection as well as Koi. Happily, Ray had quite a bit of background dealing with concrete matters; he is partners in a pool-plastering business.


Ron & Anita did their water gardening homework, before, during and ongoing... They visited the printed literature (mainly garden books), and had a real live landscape architect draw out and supervise the actual pond construction. Less than fortunate for them, they came in contact with the fine folks of the San Diego Koi Club only later. Can you think of a better way to avoid "re-inventing the square wheel" than to talk with others who've "been there, done that"? Me neither.

Be this all as it is, the basin, filters and mechanicals are all about right. The ponds sides are sloped to vertical (to avoid stimulating algal growth, fish jumping, temperature fluctuation...); adequately deep (a good 2-3 feet); big enough (broadly rectangular, approximately 40' long, 10-15 feet wide 7,000 gallons by bucket/hose/timing measure); and well placed for viewing and some blocking of the elements. The pond is directly behind the south-facing house, separated by a planting bed and walkway; affording some relief from the sun and occasional winds.

The surrounding landscape, plant selection & placement, irrigation and drainage is a nice mélange of California style; (junipers, maples, "Korean" grass"...) with a few oriental features (island, stepping stones, shallow area) and should grow to blend nicely with the surrounding plantings and flatwork.


The principal basin, main drain, and three filters are made of poured concrete of nominally eight inches thickness, coated with my favorite product for the application, Thoroseal (tm). The latter coats against alkaline leaching, lessening toxicity and making water chemistry easier to control.

The "bomb-shelter" strength of cast-concrete construction is warranted beyond aesthetic considerations. Even though we don't have freezing/expansion/cracking problems with cold weather in this part of Southern California; we do have the more-than-occasional ground shaking. Water features that will hold water through these seismic rumblings may be made of liners, molded plastics, metal and more, but some substantial reinforced (wire mesh, steel rod...) concrete is the best means of keeping the system intact and providing structure for falls, rock and other placements. I still would have incorporated a waterproof liner under the concrete for extra "insurance".

Take a look at the evenness and conformation of the concrete work; it is obvious the people involved took their time to properly set-up the forms and finish the work by hand.

Filtration: was, is and should be a chief concern in any water effect. The Provence's made several key moves in their pond filter execution:

1) Provision of adequate basin design (size, shape and location), and construction (strong, chemically inert).

2) Three separate isolatable filter basins, each with individual drainage!

An intermediate filter chamber basin with slanted biomedia technology... easily removed for cleaning! As Mr. P. demonstrates.

3) "Crater" shaped pool bottom fitted with anti-vortex drains leading to a sump/drain area to facilitate water changes and removal of settled solids and undesirable "heavier" liquids. (see photo);

4) Matched to the surface area and volume of the filters/media an appropriately flow-rate pump (1/2 horsepower Sta-Rite Max-E Glas (tm), about 25 gpm in this system), placed below grade (lower than water level), with no suction pressure/vacuum.

Lots of media, surface area here. One of the bio-filter basins in-line. 

Currently, the three filters are arranged in series, the first as a sediment trap, followed by two reverse-flow (bottom to top) red volcanic gravel beds of 12-14" depth. The cinder-rock is raised and supported by an arrangement of PVC pipe, egg-crate and shade screen. Allow me to elaborate on the sediment trap; this is a well-engineered construct of plastic rain gutter fitted with a collar to direct the water flow. The gutter is cut and joined together at an angle to maximize turbulence while optimizing the slowing of water through its channels... all this in an effort to drop out suspended solids.

Plumbing Is, thank goodness, of good (read that large) diameter and plastic all the way around. There is an allowance for overflow (through the drainage sump), ball versus gate valves, and the ability to throttle flow via a bypass arrangement. To my liking, there is no "automated" make-up system that can get these folks in trouble; instead they happily refill their pond "by hand" when enjoyably doing their routine upkeep.

Here's a view inside the overflow/individual drain sump area. What a joy to be able to simply turn a ball valve to vent waste and "heavy water from individual "basins" (craters) in various parts of the pond bottom. The uprights are filled to water level... when wiggled out of their slip couplers, the water readily flows from the pond... and out the waste line.


Livestock: Two types of fishes, ornamental carp, aka koi, (Cyprinus carpio) and some very nice variatus Platies (Xiphophorus maculatus); the second fish species installed for picking at hair algae. Aquatic and bog plants are blind-potted (no openings to the bottom) in plastic pots, fitted with koi-proof plastic net screens over their media.

Aquatic Plant Species Used:

Broadleaf Cattail Typha latifolia

Graceful Cattail ((2-3 feet) Typha angustifolia

Hardy and Tropical Lilies Nymphaea spp.

Water Iris Iris spp.

Water Lotus Nelumbo

Umbrella Plant Cyperus alternifolius

Giant Papyrus Cyperus papyrus

Pennywort Hydrocotyle umbellata

The plants they fertilize once a year, on thinning and repotting, with slow-release fertilizer tablets. The fishes are fed excellent quality white fish meal based pellets.

Bog type plants are handily kept in place and out of Koi digging in blind pots. 


Here's the REAL measure of the value of an improvement; the acid-test of how much you have to fool with it to make it do what you want. In the Provence's case, their system is spotless and functional, healthy livestock and clear water; but at quite a time cost... a few hours a week. IMHO too much.

Besides the requisite periodic water changes (some once a week or so in summer, to once a month in winter), Mr. P. finds it necessary (to prevent clogging and channeling), to get into the filters, remove ALL the media, supports, sediment trap... and hand clean entirely every few to several weeks. Ho-boy, no fun, and potentially dangerous. Those slimy surfaces are treacherous to slip and falls. Therefore, ahem my following...

What the Provence's Would Change:

In planning, Ray would really have liked to seriously chat with other water gardeners concerning adequate filtration; "The water in San Diego is so hard and alkaline, and the sunlight so intense that a pond owner really has to super-filter their water to keep the algae down". For construction it's the same; "I would definitely make the filter basins bigger dimensions all the way around; there's just too much cleaning otherwise".

Maintenance is Ray and Anita's greatest bugaboo; luckily Mr. P. doesn't seem to mind all the time and effort. "Cleaning out these filters by hand once a month during the summer is a real chore", he says; "I kind of like putting on my waders and getting in the pond though".

If they had to do it again, the platy fishes would probably be left out. "They get in the filters, the pump trap, reproduce like mad"; "We really thought they'd take care of the string algae altogether; instead they eat the Koi food".

My Suggested Changes:

1) Pump/pumping: In our part of the western world, electricity goes for a dozen cents or so a kilowatt; with pumps running continuously, this can run up to quite a bit of money for pushing water around. Hence my advice to switch to a far more appropriate (less pressure, about the same flow) pump. In this case a 1/4 HP Sequence (tm) 1000, which will produce about 20 gpm using less than half the "juice". Their current pump can/should be stored as ready back up. Happily the install already has true union couplers, so switching pumps is a snap.

2) Sediment Trap: Such devices are a great idea, and the present contraption is pure genius... but it can/will be improved tremendously by the exchange of suitable brushes for the rain-guttering. Vertically suspended brushes will trap and allow easy rinsing away of sediment by periodic shutting down of the pump, draining of the first filter basin and brisk hosing.

3) Filter Media: The amount (12" depth and 25 square feet) of igneous rock is about right for the size of the system and flow rate (1-2 gpm per square foot); but utilizing pea gravel (nominal 1/4") rock of all about the same size and roundness will greatly diminish the labor of maintenance, while maintaining high water quality. Especially...

4) Gravel Vacuuming: A tremendous advantage to the existing routine of physically removing the substrate currently, is to be gained by substituting four inches of the pea-gravel in place of the volcanic rock. With more water on top, and without shutting the system down, a large diameter gravel vacuum can be moved around utilizing a similarly over-sized (corrugated pool) hose, and the nearby embankment to siphon. No more broken egg-crate and rough, red hands; and much less time spent on routine maintenance. Yay.


When first asked what might be done to clear this system from periodic clouding by suspended algae, my response had more to do with what parameters could/might be manipulated in the way of pH/alkaline reserve, and the possibility of using alum (aluminum sulfate) as a cationic flocculent plus making the water nutrient limited. On finally viewing the pond, and meeting with its owners, I am convinced that they need not avail themselves of chemical means. With the above changes not only will the system be and appear better, the price in terms of money and time to keep it that way will be much less.

"All in all we're very happy with our pond and surrounding landscape", Anita Provence finishes our interview; "It's been a fun, relaxing hobby after all, and has done much to enhance the appearance of the property".

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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