New Pond Syndrome

Is it wabbit season? Is it duck season? No, Elmer, it’s Ponding Season.

Your contractor has vanished over the horizon at just under lightspeed to deposit that check. Alternatively (and much more likely), the backyard project that you started this spring – as soon as the ground thawed out enough to allow a shovel to penetrate the permafrost – is lined, decorated, plumbed, pumped, skimmered and maybe even bottom-drained. It’s hooked up to a spiffy new filter. The water’s in, the pumps are on and it’s time for fish! Lotsa fish! Got 5000 gallons of fresh water just sitting there!

Not. So. Fast.

Ponding is seriously addictive. It is hard for beginners to recognize that they are starting up a complex, artificial and often delicate ecosystem that is going to take Ma Nature’s own sweet time to mature. The temptation to add fish is nearly overwhelming. Especially koi – several contractors we’ve dealt with over the years actually offer new pond owners several sacrificial koi as they vanish. The First Law of Ponding is the first to take hold. Yeah, there is always a better fish. The trick is to keep them alive long enough to enjoy them.

Any backyard pond relies on a number of interlocking conditions to maintain optimum water quality and fish health.

• Reliable water sources, preferably free of chlorine and other additives (either chemically treated, well water or prefiltered)
• Enough dissolved carbonates (KH) to stabilize pH. Every molecule of ammonia that is converted to nitrate generates five molecules of acid. The carbonate salts soak up the acid and prevent the pH from dropping low enough to kill bacteria and, yes, fish. It’s called a “pH crash”. The carbonates are dissolved in the water as it comes from whatever source you are using. Water from the Great Lakes has a comfortable 120 parts per million from the limestone the water flows through. Depending on your source, your levels will be different. A good range is 80 to 120 ppm.
• Good oxygenation with turbulent waterfalls
• Competent pumps and filters
• Stable temperatures from depth and shade
• Good water movement without dead spots
• A clean and easily-maintained bottom
• And, most importantly, a way of getting rid of the waste products that those fish are generating.

This is biofiltration, also called nitrification, and it relies on the activity of several species of naturally-occurring bacteria. They need media with a large enough surface area to allow them to establish a biofilm in which to interact with the water and convert the ammonia the fish are producing to relatively nontoxic nitrates.

New ponds do not have any of these populations present at startup. It takes weeks to get them introduced and functioning. The different bacteria do not all develop simultaneously. The bacteria that convert ammonia (toxic at moderate levels, worse with higher water temperatures and higher pH) to nitrite (toxic under any conditions) develop first, usually over a one to two-week period after startup. The bacteria that take nitrite to far-less-toxic nitrates take several more weeks to develop, regardless of the excellence of the new high-tech filters. Almost all the bottled “Insta-Startup” bacterial additives available commercially are not terribly effective, with one probable exception.* {A better solution would be to get a generous sample of active filter media or mat from a mature pond and put it into your filter (if possible) or even just into the pond.}

The result is called “New Pond Syndrome.” You’ll know you’ve got it when all those new fish you put in on day 1 are dead by day 15. The first wave died from the ammonia and the survivors succumbed to nitrite poisoning (similar to carbon monoxide poisoning in mammals). Water testing will reveal a rapid uptick in ammonia as the fish go in, followed by a gradual decrease. As ammonia drops, nitrite climbs and, over a week or so, begins to drop off. You are done with the first stage of this when both of these levels have returned to zero.

The preventative solution to this initial problem is either to pretreat the pond with household (NOT sudsy!) ammonia and wait for the levels to drop before adding any fish (not recommended) or adding only one or two fish at first and feed very lightly, again, until the levels drop to zero. More fish can be added gradually, to the capacity of the filter and pond.

We call it a syndrome because it doesn’t go away. It generally takes a backyard pond five to six years to achieve a robust enough population of filter bacteria to survive stresses. The most common stressor is winter shutdown. For many ponders, this means shutting down the pumps and filters and blowing out the plumbing to prevent freezing related catastrophes. This deprives the bacteria in the filters of oxygen; the cultures left on the pond walls go dormant. Come spring, these populations will revive, but with the same timetable the owners saw at startup. This does improve as the pond matures, but it is still a major water quality issue every spring, especially as the fish wake up and demand to be fed.

The simplest solution to this is to protect the pond with a weather cover or poly house. Add strategies to keep the water temperatures at or around 40 degrees F., maintaining flow through the filters all winter. The filter bacteria do go dormant, but bounce back very quickly in the spring.

An even simpler solution to this problem (although logistically challenging) is to move the family establishment somewhere without winter and dig your pond there.

A popular alternative to “high-tech” biofiltration is the installation of a bog filter. This is basically a separate container of water, preferably about 20% of your pond’s volume, heavily planted with aquatic vegetation. Water arrives from your pumps and flows around the roots of the plants which remove the ammonia and also provide some mechanical filtration. From there, the water descends to your pond. Fish do not belong in the bog. A new startup with a bog actually takes much longer than a high-tech system, since it requires the plantings to settle in and mature. While these tend to be hardy perennials, they do die back in the winter and have to re-establish themselves in the spring. Obviously not a problem if you do not have winter.

The most common error that can perpetuate New Pond Syndrome indefinitely is the mistaken assumption that a backyard pond needs to be spiffy-clean everywhere: drained, pressure-washed and stripped of all that nasty algae, refilled and dosed with ineffective supplements. It happens more often with gravel-bottomed liner ponds, since the gravel traps sludge and there’s no other way of getting it out. Pressure washers classically hook up to the garden tap delivering cholera-proof chlorinated water to the device and onward to the entire pond system, killing the bacteria and restarting perpetual NPS.

So, some advice:

• New pond? Start slow, only a few fish and feed lightly
• Water test daily until ammonia and nitrites are zero.
• Beware of Spring. Feed sparingly as the pond wakes up.
• Avoid winter if at all possible
• Protect the pond in the winter. Keep the pumps and filters running if at all possible.
• Do not put gravel on the bottom of the pond. The guys who want you to do this need an excuse to come back every six months to pressure wash your pond and destroy your filters. Again. For $1000 a pop.
• Do not pressure wash your pond. Ever.
• Never add chlorinated water to your pond or wash any part of your filter with chlorinated water.
• Bacteria boosters mostly do not work.*

* A company called Fritz-Zyme provides start-up cultures for large aquarium installations (like the Shedd in Chicago) that have to be used within 24-48 hours after initial prep. This is shipped refrigerated and costs $$$$$$$$$$$. They make a hobbyist version, also shipped cold, that works well. It’s called TurboStart 700 and works over a 5-day period.)

By: Bob Passovoy

Published 2/8/22

Who’s on pHirst?

(This article is being written during the Super Bowl. (Actually Super Bowl XX, 1985. Bears vs. Patriots. Got it on tape 35 years ago.) So a sports metaphor is appropriate, even if it is baseball!)

Alright, keep your hands off the keyboard. Step away from the door and sit down. Do not run away. We are your friends, and a discussion of pH is not going to hurt you. Much.

Every time pH is mentioned in ponding circles, especially in print, the sound of eyeballs glazing over is well-nigh deafening. I don’t know why this is, but it seems to be one of the hardest things to explain in any fashion that leaves the listener (or reader) conscious and mentating. I’ve seen definitions involving ions and balances and atoms of hydrogen and oxygen. I’ve seen demonstrations of formulas worthy of Einstein and Planck at their most opaque, but I don’t know that I’ve seen much that was useful for the average backyard ponder.

I guess the best way to start is with some generalizations. These are not necessarily the total truth, but as a very wise man once said, they are very useful lies.

• Every pond exists with a balance of acid and alkali (base) components as constituents of the soup that we call pond water.
• Acids are things like lemon juice, vinegar, and the stuff inside your stomach.
• Alkalis are things like quicklime and concrete.
• Both, in high concentrations, can eat holes in things. (Did you really need to know that? No, but it’s fun, so I said it anyway.)
• Both are present to one degree or another in our pond water and are either a part of the water itself or of the minerals (or pollutants!) dissolved in the water.
• If you have equal amounts of acid and base in your water, these balance out and this state is called “neutrality”.
• pH is a convenient way of measuring this balance, with a pH of 7 reflecting the neutral state. Numbers less than 7 indicate a more acid state, and those above 7 a more alkaline condition.
• pH changes are logarithmic (don’t panic!) To quote Norm Meck, my Chemistry guru, each whole unit of change is 10 times more than the previous one. pH 8 has 10 times more base than pH 7, and pH 9 has 10 times more base than pH 8 (100 times more than pH 7!).  The same is true for acid at pH values below 7. pH 6 has 10 times more acid than pH 7, and so on.
• Dissolved materials, such as ammonia, are affected by the pH balance in our ponds, and their ability to harm our fish depends on the pH level.
• The bacteria in our filters function best within a narrow range of pH, and sudden changes, especially in the acidic direction (low pH) can wipe out our bioconverters.
• Koi are tolerant of a wide range of pH, as long as it is stable.

There, that didn’t hurt too much, did it?

It isn’t really necessary to completely understand every nuance of the chemistry and physics of pH, but it is important to be able to measure it accurately on a regular basis, to understand the importance of maintaining a stable pH, and the consequences of failing to do so.

Measuring pH

A trip to any pet supply store will present you with a number of choices of pH kits. These range from little bits of paper only one step removed from the litmus paper you played with in science class, to tablets in little indestructible foil pouches, to bottles of mysterious fluids. Regardless of which you buy, a few things need to be considered before you plunk down your money.

1. Is the kit you are buying sensitive in the range you need? Ideally, ponds should operate in near-neutral water conditions (7.0-8.5). In reality water pH can vary anywhere between 6 and 8.5 and still be perfectly healthy. The pH can vary with time of day, water source, additives, pollutants, plantings and a host of other influences. As long as the changes are gradual, koi tend to be pretty tolerant. Bio-converting bacteria tend to lose efficiency at low pH, and pH above 9 is thought to damage koi kidneys. Many pH test kits vary in accuracy and are accurate in only a specific range of pH. A kit with a very wide range may not give accurate readings in the range you need. A very accurate kit within a narrow range of pH won’t let you know if you are in trouble outside that range. In general, any kit that will give you easy-to-detect color changes in a range between 5 and 10 (“wide-range”) is satisfactory for pond use. For those of us with color-blindness or a need for micro-management, electronic pH meters are available. These require frequent calibration and maintenance and are often fragile. The average Joe Ponder need not make this investment.
2. Are your reagents fresh? Testing materials bought from pet supply stores are often ordered months in advance, and can sit in storage areas (often without temperature or moisture protection) for weeks to months. Before that, they can reside in warehouses for as long or longer. Even specialty suppliers have been known to send old and inaccurate reagents to hobbyists. Your best bet is to order from a supplier with a good reputation for reliable reagents and a mechanism for tracking lots of reagents by date of manufacture. Most pH kits have a shelf life of about two years. After that they should be replaced.
3. Is the kit easy to use? Complicated testing procedures will discourage you from keeping up with your monitoring program. Most good pH reagent kits are one-step and can be read almost immediately. Any kit with instructions written in engrish as translated from the original Japanese by a native Tagalog-speaking Scotsman should be gently replaced on the rack, as should any kit that requires endless shaking of an insoluble and indestructible tablet.
4. Will the kit last the season? Many reagents are sensitive to deterioration by moisture, heat and/or sunlight. Make sure your kit is appropriately packaged and the quantities are sufficient to last you long enough to make the purchase worth your while. If you are buying paper strips, for instance, water-tight packaging is a must!
5. Why do I have to measure pH, anyway? Ah, now. On to the next section.

Maintaining stable pH

pH is not a fixed value in any pond. It is a constantly changing dynamic balance between acid and base that can be affected by a multitude of environmental influences. Without some stabilizing mechanism, pH can vary widely and rapidly, not a good thing for the fish or the filter. What keeps this from happening is the presence of dissolved salts of magnesium, calcium and other minerals which are capable of swapping acid and base components within the pond environment. These are present in most water sources, so that frequent water changes can replenish these salts, which are broken down and consumed by organic acids produced by common pond bacteria. If you think of these salts as a big sponge, sopping up the acids produced by rainfall, fish, bacteria and other sources, and minimizing the effect the added acids have on the pond environment, you are close enough to the truth to make it useful. We call this “pH cushion” a buffer, we measure it as alkalinity(or KH), and the action of alkalinity on a pond is its buffering capacity.

The term we use for the strength of this protection against pH shift is Alkalinity, measured in parts per million (ppm), and test kits, subject to the same questions and requirements as your pH kit, are widely available. Ideal alkalinity is around 100 ppm; a range of 80-200 is acceptable for most ponds. This means your test kit will need a range of 0-200 to be useful.

Attempts to change pond pH rapidly by the addition of acid or alkali directly to the water usually result in major stress to the fish and filter. As long as the pH is stable, ranges of pH between 6 and 8.5 are well-tolerated, and it is a better idea to find ways of stabilizing your pH. This is actually fairly easy to do by watching your alkalinity, and supplementing it if necessary. Supplements can be as simple as a “biscuit” of plaster of Paris placed in the pond and replaced as it is consumed works well. Emergency corrections of alkalinity can be made with simple Arm & Hammer baking soda (pure sodium bicarbonate). Most ponders of my acquaintance just use the bicarb. It’s cheap, easy to find and eco-friendly. 1 pound of the stuff per 1000 gallons of water buys you 70 ppm alkalinity.

So… What if I Don’t?

Wide shifts in pH over short periods of time are stressful to both fish and filters. Water that is very alkaline (pH 9.0) has been suspected of damaging koi kidneys. Since the addition of acids to ponds is very tricky, a water source that is less alkaline may be preferable.

Sudden reductions in pond pH can occur in liner ponds without access to rock or other sources of salts, as alkalinity is consumed by the production of organic acids, reducing its buffering capacity. The most common source of these acids is the action of our beneficial bacteria as it converts ammonia to nitrate. Each molecule of ammonia that is processed results in the production of five molecules of acid.

For those of you out there with a biochemical bent, here’s what is really going on:

NH3 (ammonia) + O2 (oxygen) à NO2 (nitrite) + 3H+ (hydrogen ions=acid) + 2 electrons

This reaction is powered by Nitrosomonas and Comammox bacteria, which show up earliest in a new pond and cause the famous and dangerous “nitrite spike” in new ponds and any pond shut down for winter.

NO2 + H2O (water) à NO3 (nitrate) + 2 H+ +2 electrons

Nitrobacter, Nitrospora and Comammox bacteria handle this step and tend to wake up 1-3 weeks later. Nitrates are relatively nontoxic and can be eliminated by vigorous exposure to oxygen in a bioreactor or Bakki shower.

The key take-away is that each molecule of ammonia that your fish generates will generate 5 molecules of acid that has to be buffered by your pond’s alkalinity. A few hot days with heavy feeding, or even a heavy rainstorm (rainwater contains no dissolved salts!) can drop your alkalinity to dangerously low levels very quickly.

An efficient biofilter doing its job in high summer in a heavily-populated pond can chew up the available buffer very quickly. When this happens, the pH can drop suddenly and without warning, a phenomenon called a “pH crash”, which can drop the pond pH to 5 or less. Since the bio-converting bacteria in your filters lose efficiency at pH below 6, acid conditions of this intensity essentially turn off your filter’s ability to process the ammonia your fish are still making. It will now take weeks to get it back, since very low pH will kill a significant portion of your bacterial population. Your fish are protected in the short run because ammonia becomes ionized at low pH, and is considerably less toxic. Trying to correct the pH towards neutral without first binding the ammonia with an additive will de-ionize the ammonia and kill the fish.

Overall, weekly monitoring of pH and alkalinity, and supplementing the alkalinity as needed, can save you a lot of trouble and heartbreak, and get you that much closer to an ideal pond.

Respectfully submitted,

Bob Passovoy