Pimp my Pond by Dr. Bob Passovoy

Well, now you have gone and done it. For whatever reason, you are now a ponder. Your contractor, check in hand, has just vanished over the horizon in a cloud of dust, leaving you with your spiffy new backyard water feature. If you are very lucky and very smart, you will have had the benefit of friends grown old in the hobby and a contractor who knows his stuff. If you have the usual beginner’s luck, you’ve got a shallow hole in the ground with about 24 to 36 inches of water in it, a few (expensive) sacrificial koi, a skimmer at one end and a tub of water at the other, casting a wonderful smooth sheet of water into the (for a while) limpid depths.

This is the most dangerous time for a ponder. The Three Laws have bit you and the First Law (There is always a better fish) is generally the initial force to take hold. It is too early for you to realize the force of the Third Law (There is never enough water). You haven’t had the chance yet to overstock and overfeed.

You’ll find the sheer power of the Second Law growing as you gain experience and sophistication. It is of the Second Law we speak. There is always a better filter. For filter, substitute GADGET.

As your pond increases in size and your expertise grows with experience, you’ll begin to notice…deficiencies…in the way your system handles stress, weather, fish load and water quality, and you’ll be looking for ways to fix them.

Forthwith, a series of challenges and what could, given the right conditions, develop into a very impressive Christmas wish list.

Challenge #1 occurs as you settle into the hobby and your fish grow in size and numbers. Your water warms up as it is bathed by the sun’s happy rays and you have achieved…ALGAE! It starts as a faint green tinge to the water and suddenly you can’t see the fish. You need a solution because you read somewhere that floating microscopic algae sucks up oxygen in the dark. Off to the pet/sortapond store where the guy tries to sell you a bottle of something that is guaranteed to kill off all the algae in your pond, no worries. Just in time you remember that any chemical you put in, stays in until you can water-change it out. You also reason that the proteinaceous gook that’ll collect as the plant life dies will stay in the pond forever as well, giving you that healthy head of foam at the foot of your falls and that odd brown tinge to the water. So, nope. No chemicals. You needs a GADGET! There are a few.

First up in your mind are UV (ultraviolet) clarifiers. These are not filters as such, nor are they “sterilizers” unless you are ready to shell out several thousand dollars on an industrial-strength array capable of knocking a GPS satellite out of orbit. These high-end devices, set up properly, are powerful enough to kill some motile parasites and even see use as ozone generators, but they are aquaculture tools, not designed for backyard ponds. Hobbyist UV units will cost between $50 to $300, depending on the design and durability. They run with bulb capacity between 25 to 100 watts as a rule, the bulbs retaining their punch for about a year. The key to their effectiveness is the amount of time the water piped into the unit stays there. Most hobbyist UV units are set up with 1-inch or 1 ½ inch connectors to slow the flow. For this reason, the UV unit should always be set up on a diversion loop on your filter outlet pipe so that full flow back to the pond is not impeded, remembering that this fits in after the water has been mechanically and biologically filtered. UV in this application does not kill anything. It does cut down on floating algae by damaging its ability to reproduce. It will not affect anything in the pond itself, so don’t expect all that hair algae to disappear. These units need their bulbs changed out every year, and the plastic-bodied devices tend to get brittle after a few years of UV exposure and will disintegrate. Look for UV with stainless steel chambers and robust fittings. In general, UV is affordable and works well within its narrow application.

MAGNETISM! Nobody knows what magnets do when you wrap them around pipes. We do know that they do not affect algae.

IonGen: This infernal little device kills algae. And plants. And, eventually, fish. It is a block of copper or zinc hooked up to a DC power source and then exposed to your pond water. It uses the Mad Science principle of electrolysis to erode the metal, releasing molecular copper or zinc into the water. As it operates, the metallic ion concentration becomes toxic enough to kill off algae (leaving the organic pollutants in the pond for you to deal with). As the unit continues to run, levels of copper can easily reach levels toxic to fish. Everything dies. Do not waste your money. There are better solutions to this problem.

Ozone: Oboyoboyoboy! High-tech Mad Science! Ozone is the ultimate oxidizer. It breaks down proteinaceous waste, kills parasites, kills algae, kills bacteria, and if it gets out of control, toasts off fish gills. Alan LaPointe, the head water-quality guy at the Shedd Aquarium wears a beeper 24-7. It connects him to the equally 24/7 monitoring staff whose job is to watch the ozone levels.  All The Time. He says that if you are not prepared to exert this level of effort and vigilance, do not do ozone.

So now what? You got your UV and you still got algae. Maybe less than before, and more hair algae than floating, but still algae. Now is the time to remember what promotes algae growth. Warm water. Sunlight. Food. Food? Algae eat ammonia. Fish make ammonia. You got lotsa fish. The algae are happily taking the ammonia out of your system and converting it into plant. You want it to stop? Get rid of the ammonia. You need MORE FILTER!

Prefiltration: Koi are bottom-feeding fish that love mud. In their natural habitat, you’ll never see them. Koi keepers are natural voyeurs and want to see their fish all the time. “Gin-clear” water is the holy grail of the backyard ponder, even if it’s not the ideal habitat for a carp, and that means no floating crud. Getting the big, visible chunks-‘o-stuff out of the water improves the pond’s appearance and reduces the amount of time you’ll have to spend flushing the crud out of your biofilters. Prefilters range in complexity from a piece of filter mat wrapped around that submersible pump to stainless steel screens with holes too small to see. Oddly, as the complexity of the device increases, maintenance on the device decreases. What’s most important here is that the water hits this first, before the biofilter and definitely before the pump.

Seives: Usually a plastic basket that fits over the inlet of your submersible. Fouls instantly. Also found as a basket on the inlet side of dry-land pumps. By itself, also high-maintenance.

Foam pads and mats: Placed somewhere between the inlet to your pump and the pump itself, usually contained in a box or just wrapped over the inlet, these have the advantage of being simple and cheap. The downside is that they foul quickly and need to be cleaned frequently, often twice a day at the season’s peak.

Vortex: Basically a big tub with a conical bottom. Water comes in passively from the pond and enters the tub in such a way as to create a constant swirling motion. Larger particles settle out to the bottom and the cleared water is drawn off the top and sent on to the filter or the pump. Simple and easy to maintain, but it takes up a lot of space.

Turbovortex: This is a prefilter adapted for closed systems. It is very compact, basically a small upflow filter partially filled with a coarse mechanical media. ¾-inch bioballs are most frequently used. It does need daily backflushing and the valving systems available to allow you to do this range from “instant-foul-and-fail” to “impossibly arcane”. I have one. It works. Don’t ask how.

High-tech sieve: These range all the way from self-contained large-volume sieves in flashy stainless cylinders to elegant bow-screen sieves with teeny-tiny holes and elaborate backwashing systems.

As the complexity of the system increases, so does the thoroughness of the mechanical prefiltration and the cost. Adding prefiltration boosts the efficiency of your bioconverters, but you’ll need to shop around to find the prefilter that fits your pond best.

Biofiltration: The idea here is to provide the maximum amount of surface area for your filter bacteria to stand on in the minimum amount of space. Biofiltering bacteria rely on biofilms which stick to surfaces. Filter media which provide a very high surface area for a given volume and do not foul or clog are preferred, as are the systems that use them. The system needs to fit the requirements of your pond from the standpoint of flow and volume and be compatible with whatever pumps you are using. It needs to be reliable and easy to maintain and clean. Beyond that, nothing else matters. Open system, closed/pressurized, Nexus, home-built. They all work. The limiting factors are cost, space and physics. The critical point is whether the system is capable of keeping ammonia and nitrite at or around zero on a consistent basis, regardless of the stress. If it can’t, you need more filter. If it can, you don’t have an algae problem anymore. You do have happy fish. If you have multiple systems, they need to be hooked up in parallel if you have only one inlet. If you have both a skimmer and a bottom drain, split the systems and run them independently, each with its own pump, prefilter and biofilter. This redundancy gives you some safety if either of the systems dies. It also gives you more pipe room to add more toys. Gadgets! Remember?

Dissolved Organics: Otherwise known as protein, foam, gunk, sludge and “that funny brown color that my pond turns in the summer. This is the result of natural processes that involve broken-down sloughed slime coat from the fish, dead bacteria and decomposed plant material. Besides being responsible for that ugly bubbly foam at the base of your falls, it is also a pollutant that degrades water quality and fish health. Better it should be gone. Water changes will dilute it, but getting rid of it requires a Protein Clarifier. Otherwise known as foam fractionators, these have been available to aquarium hobbyists, especially the salt-water reef guys for a long time. Ponders, only in the past five or six years. The principle is simple. Agitate the water enough (Venturi, air or both) and it foams. Foam floats and can be skimmed off, returning the defoamed water to the pond. Commercial units (Clarity and others) are available and adaptable to just about any filter system, and like any purpose-built manufactured gadget, cost big bucks. Generally 900 to 1300 dollars. A brisk search through Google reveals several plans for do-it-yourself projects, mostly involving novel uses of various bits of PVC. These work just as well, and bring the cost down to around fifty bucks. Either way, it is worth the time, money and effort.

Degassing: The end product of biofiltration is Nitrate. The end product of buffering (pH balancing) is carbon dioxide. Both can accumulate and both can negatively affect fish health. Luckily, both are governed by chemical reactions that have a gas at one end of the equation. Get rid of the gas and you get rid of the toxin. Ma Nature provides for this with waterfalls. Big, rough, splashy waterfalls. The idea is to maximize the contact between water and air with turbulence at the air/water interface. Airstones DO NOT DO THIS! They are great at moving water, but there is just not enough surface area on each of those spherical bubbles to allow enough gas exchange to matter. The simplest solution to this problem is to engineer in big splashy waterfalls and fast shallow streams and rapids when you dig the pond. Otherwise, you need more GADGETS(!).

Trickle towers are the simplest and cheapest solution to this problem. In their basic form, they are an upright row of 4-inch PVC pipes filled with coarse filter media (usually bio-balls) standing on end in a trough with an outlet to the pond. Water is pumped to the top of the array through a pipe with holes drilled to allow water to pour freely over the media. CO2 and N2 are released, Oxygen is introduced and the water and fish benefit.

Bakki showers employ the same principle. Water pumped to the top of the system through a spray bar is dumped into a perforated trough filled with coarse filter media. It splashes down to another similarly loaded trough, and another and maybe another and then back to the pond. The media can be ferociously expensive imported Japanese ceramic logs or Tuffy sponges. The system can be a glossy array of purpose-built stainless steel or a stack of plastic window boxes supported by 2x4s. The principle is the same, as is the end result.

Bioreactors work a little differently and are more efficient biofilters while still allowing for efficient degassing. Basically a large barrel with airstones at the bottom hooked to a powerful air pump and filled with a neutrally buoyant media such as Kaldenes. Water flows in from one side of the barrel and exits out the other side as the bubbles agitate the media. This is a low-flow gravity-drained system, more compact and concealable than trickle towers and Bakki showers. Also home-buildable.

Air: Air pumps are one of the essential tools in ponding that everyone forgets and then adds as an afterthought, usually assuming that they’ll solve the dissolved oxygen problems mentioned above. They won’t, but air has lots of other uses. How you supply it depends on what you want it to do.

Agitation: Air moves water better and cheaper than anything else. Once your pond is set up, watch for places where debris collects, both on the surface and on the bottom. These are dead spots and will become home to sludge, anaerobic bacteria and parasites. An airstone supplied by a robust pump will move water out and eliminate the dead spot.

Winter: One of the older techniques for maintaining an open area on an unprotected pond’s surface. Robust air pump, airstone one foot below the water’s surface. Voila! Hole!

Gas exchange: This is your bioreactor speaking…(also your Nexus and Helix filters!)

Filter backflush: Pressurized filters, regardless of the media used, accumulate sludge as a consequence of mechanical and biological activity. As long as the stuff is in the filter, it poses the same risk as it does in your pond. Most filter backwash cycles don’t generate enough turbulence within the filter to shake the crud off the media and the subsequent fouling degrades filter flow and efficiency. Adding an air blower step to your backflush sequence amps up the agitation of the media, shakes out a lot more of the dead stuff and makes the whole backflush process more efficient.

Heat (Southern and Southwestern ponders may ignore this bit): Ice and snow are not your friends, no matter how much you like skiing and skating. Your fish hate it. Ice seals off your pond’s surface, trapping the gaseous breakdown products of the decomposition of that junk on the bottom in the water. Snow carries pollutants and causes major temperature fluctuations. Open water, protected open water is best.

Trough heaters are available everywhere, their purpose is to maintain a small open area on the surface of the water trough so the cows, goats, sheep and horses can get a drink in the winter. When applied to a backyard pond, they have a nasty tendency to fail catastrophically, usually on the coldest days, either just dying and allowing the pond to freeze over, or shorting out, dying while delivering a jolt of 120-volt AC to your fish. This can cause permanent spinal injuries and deformity. These gadgets are inexpensive, but their failure rate under adverse conditions make them a false economy.

A reasonable middle-road solution is to cover your pond in the winter with a poly-house. These are available as kits and I know of at least one business in the Chicago area that will design and build it for you, then set it up in the fall and strike it in the spring. They are relatively inexpensive (cost depending on size, of course) and have the advantage of protecting your pond from environmental changes. With a little added heat to the air under the plastic, your water stays liquid and your pumps can run year-round. Locally, Midwest Trading in St. Charles, IL sells the kits.

At the other end of the scale are the purpose-built pond heaters. Either electrically powered or gas-fired, the best of them use a countercurrent flow heat exchanger to heat the pond water. Expensive to buy, expensive to install and expensive to run, they still give you the most accurate control over your pond’s water temperature available, short of installing your pond indoors. You don’t want one of these unless your pond is covered. You don’t need one if your pond is indoors.

Finally, Power: A backyard ponder is wholly dependent on electricity for the operation of pumps, heaters and all the other stuff needed to keep his water clean and his fish alive. One major, prolonged power outage is enough to kill the pond and everything in it. An emergency electrical generator is a wonderful thing to have. Small gasoline-powered generators are relatively cheap and available at any Home Despot-equivalent, but have the drawback of requiring constant tending and your presence on-scene at the beginning of the outage. An automated whole-house unit with a computer sensor that can sense the power loss and switch on the generator automatically, as well as turn it off when power is restored is a much better deal, especially if what you buy has enough punch to maintain your house electricity as well. In fact, that is how you tell a Ponder from a Normal Person. The Normal Person will buy a generator and the first protected devices are his entertainment system and the central air conditioner. If his S.O. has a big enough stick, the kitchen is usually next. A ponder dedicates the first four circuits to the pond and isolation tanks. Whatever is left over goes to the freezers where the high-end koi food is stored. Then the kitchen. All of these devices can run on gasoline, propane and natural gas with minor adjustments.

Ponding is a lot like model railroading. The layout is never done. There is always one other thing you can add to make it PERFECT.

Bob Passovoy

June, 2016