It is caused (once again) by too much nutrients in the water. This algae is found most commonly during spring and summer. To eliminate this problem, the proper filtration of the water is important. Either biological or mechanical filtration is required to remove the highly fertilized water and reduce this algae problem.

What is pH and Hardness? pH refers to the acidity or alkalinity of water. Different fish have learnt to adapt to different pH levels, thus, it’s important to know the requirements of your fish. Although many fish can adapt to a range of pH levels, fluctuations outside this range may well prove fatal.

It is important therefore to remember that readings should be taken regularly from specimen water samples and adjusted as appropriate. Proprietary water treatments can be bought which will alter (buffer) pH levels.

There is a direct relation between pH levels and the toxicity of ammonia. When pH levels are low, ammonia is less toxic.

The origin of your water determines its hardness. Water originating from rain absorbed through the likes of chalk, limestone and clay is hard. That absorbed through clay being of Permanent hardness, and that through chalk and limestone being of Temporary Hardness. Water originating from rain absorbed through peat or other organic matter will be Soft.

There is a link between Hardness and pH in that Hard water is either neutral (pH 7.0) or alkaline (above pH 7.0) and Soft water is acidic (below pH 7.0).

A pH measurement will help us determine if our water is a proper place to put the fish. For our Koi ponds, the pH should normally be between 7.0 and 8.5, but it is probably acceptable to be anywhere between 5.5 and 9.0. Although most of the fish could tolerate a pH as low as 5.0, bio-converter bacteria are subject to damage. Long term conditions above 9.0, can cause kidney damage to the Koi.

pH impacts fish in several ways:

First, if the pH is too low, a condition within the fish called “Acidosis” results. Symptoms are anorexia, and then production of excess slime, isolation, and resting on the bottom, finally, streaking of the fins, and death will occur. If the pH is too high, the fish will produce excess slime, and will gasp at the surface. Losses can be major. “Alkalosis” is hard to reverse once it occurs. On the other hand, Acidosis is rapidly corrected once the pH is brought up to a suitable range.

IMPORTANT: pH is an indicator that shows the toxicity of Ammonia. At higher pH values, ammonia is more toxic. Below pH 7.2 most Ammonia is ionized to “Ammonium” and is far less toxic. This has relevance if you are considering raising the pH in a system with accumulating ammonias.

Test kits are available that use drops, pills, or powders with a color chart to show various ranges of pH. A wide range pH test kit (Range 5.0 – 10.0) is considered as a requirement for all ponds. If higher accuracy is desired, one or more limited range test kits are nice to have for the ranges most often encountered. Battery operated, digital electronic pH meters are available that measure from 1-14 in 0.1 increments. Most of the inexpensive versions of these ($100 or less) provide readings that are both temperature and battery condition dependent. All require periodic calibration and the less expensive ones usually require calibration prior to each use. Since doing this calibration is more involved than making a chemical reading of the pH, an electronic pH meter is not considered appropriate for most pond keepers. Those who have difficulty distinguishing the small color differences of the chemical test color charts find them wonderful.

pH is prone to “fall” in un-buffered systems, and can fall precipitously due to Oxygen consumption, accumulation of Carbon dioxide, decay of fish and other wastes, and the normal activity of nitrifying bacteria which reduce Ammonia to Nitrite.

“Crashes” from a normal pH all the way down to pH 5.5 can occur overnight. At 5.5 the filter bacteria that may have contributed to the crash will shut down, preventing the crash from dropping yet further.

In systems where the pH has been chemically stabilized by any of the commercial buffers, the pH crash phenomena is not commonly seen.

You may already have noticed that the water pH even fluctuates during a day. For example, the reading is the lowest at the dawn but the highest in the afternoon. According to a study conducted by the University of Maine, the water pH will increase as the water temperature increases. However, the effects of photosynthesis on the plants life in the pond is far outweighed the effects of the water temperature. Plants give off more oxygen through photosynthesis than they give off carbon dioxide (CO2) through respiration. As oxygen increases and the carbon dioxide decreases, it results the water pH to go up.

Treatment

Much more important than either the actual pH and alkalinity measurements, assuming they are both in the acceptable ranges, are CHANGES to them. A typical established pond will normally settle down into an equilibrium state with a pH of about one half unit above or below the pH of the tap water used for replenishment. Over time (months), all of the inhabitants (bacteria, plants, and the fish) become acclimated to their environmental conditions. Stress occurs in all of them if they must adjust to any changes. Rapid changes in pH can cause extreme stress to the fish similar to shock in humans. A sudden change of a half or more pH unit in an established pond is an indication that something happened and the cause should be determined. Slow, longer term, changes provide other indications. Increasing pH and/or alkalinity trends in a pond are normally caused by lime leaching out of concrete and to a lesser degree by concentration due to evaporation and decomposing organic matter. Decreasing pH and alkalinity tendencies are primarily due to bacterial action that release acidic compounds. Concrete ponds usually stabilize at a slightly higher pH value than ponds with liners. Established ponds will normally maintain their equilibrium pH value if sludge and decaying organic material is routinely removed from the pond, mechanical filter, and biological converter. Scheduled water change outs (10% per week for a small pond, less for larger ponds) are also helpful. Monitoring the pH by recording weekly readings (before the water change outs) can provide an excellent indication of any developing problems. pH values do change somewhat during each 24 hours, depending upon the temperature, quantity of plants (algae and others), and the size of the pond, so try to take the measurements at about the same time of day. Alkalinity measurements can provide a warning that a pH problem may be imminent.

If the pH gets out of control, high or low, increase aeration and conduct daily water change outs to bring it back into range. Recheck after each water change out and again in 24 hours. At a pH of 6 or 9, do daily 10% to 25% water change outs. For a pH of 5 or 10, do 25% to 50% water change outs. At pH extremes approaching 4 or 11, remove any remaining fish. CAUTION: Be sure and check and treat for any Ammonia presence BEFORE attempting to raise pH through either chemical or water change out means. Only under EMERGENCY conditions should chemical means be used to adjust the pH in a pond. Attempting to lower the pH chemically can be particularly hazardous to you, the biologic converter, and the fish (not necessarily in that order).

Repeating for emphasis, the value of the pH measurement, within the acceptable limits, is of little importance. A change, whether sudden or a slow trend, to the pH of an established pond, indicates action may be required and is why periodic pH measurements are important. Further, if your pH is reasonably stable and anywhere between 7.0 and 8.5, not only is there no need to attempt to adjust it, you probably will do more harm than good by trying to change it.

Ammonia is toxic to fish. Exposure to ammonia results in an increase in mucus on the fish. The increased mucus may harbour bacteria and parasites which will cause infection. Gills may also become swollen and both will result in the reduced ability of the fish to absorb oxygen.

Typical symptoms include:

• Increased mucus layer on fishes mucus membrane.
• Swollen gills.
• Fin rot.
• Flicking against hard surfaces.
• Gasping at the surface of the water.
• Inability of fish to maintain its balance in the water.

Ammonia is present in water as a result of the following:

• Excreta (overfeeding produces more excreta).
• Decaying, uneaten food.
• Decaying plant material.
• Dead and decaying livestock.
• Filters can become blocked by any of the above thus reducing their efficiency.
• Filters that are deprived of oxygen can cause ammonia to be returned to the
• aquarium.

Reduce Ammonia by the following:

• Reduce feeding.
• Reduce stocking levels if overstocked.
• Feed with a good quality food substance.
• Remove dead and decaying leaves and plants.
• Clean tank regularly (bi weekly recommended).
• Clean filters according to manufacturers instructions.
• Ion Exchange Filter Media such as Activated Carbon, Charcoal and Peat can
• remove ammonia.
• Partial water changes.
• There are two different types of ammonia: Ammonium and Free Ammonia. Ammonium is relatively safe for fish, whereas Free Ammonia is extremely toxic. There is a direct connection to temperature, pH and Ammonia as follows: High Temperature & High pH = High levels of Free Ammonia.
• Low Temperature & Low pH = Low levels of Free Ammonia. Proprietary kits can be purchased to monitor levels of ammonia.

High levels of nitrites are also toxic to fish.Those steps listed above to reduce ammonia should effectively reduce levels of nitrites.The most common sign of nitrite poisoning is the fish gasping at the waters surface.Proprietary kits can be purchased to measure nitrite levels.

Nitrates are the end product of the breakdown of ammonia. It would be more worrying if Nitrates were not present in the water as this would tend to suggest that the filter is not functioning correctly.

High levels of nitrates aren’t generally harmful to fish, but there are some very delicate species that will succumb to illness if exposed to high levels for a long period.

Levels of Nitrates can be reduced by changing water and increasing planting (which will absorb nitrates as fertilizer).

Proprietary kits can be purchased to measure nitrate levels.

Surface area is all important to the oxygenation of the pond water. Aeration increases the surface area of water that comes into contact with the air.

In warm temperatures, the amount of oxygen that can be dissolved in water decreases. At the same time, fish are more active in warmer temperatures and thus their requirement of oxygen is greater.

The complete opposite happens in cooler temperatures where the water can dissolve plenty of oxygen.

Fish that are deprived of oxygen may cause suffocation. Symptoms include:

• Gasping at the water surface.
• Congregating near oxygen sources.
• Fish may stop eating.
• Too much of Carbon Dioxide (CO2) in the water can also lead to Oxygen Starvation. As a bi-product of photosynthesis and respiration, plants produce Carbon Dioxide at night. High levels of Carbon Dioxide can decrease pH levels, thus oxygenation is essential.

One way to increase oxygenation is through aeration from either a returned filter outlet, a waterfall, a fountain or an air pump. Water returned from a filter can agitate the waters surface thus increasing the surface area and in turn, the amount of oxygen the water can dissolve. Air pumps will also create oxygen rich water by introducing oxygen directly into the water along with the fact that submerged bubbles will increase the waters surface area. Many smaller bubbles provide a greater water surface area when they submerge compared to fewer, larger bubbles.

Chlorine (Cl) is a gas which is added to municipal water systems to control harmful bacteria. In the United States, if you don’t have a water well on your property, you probably pay for chlorinated water. Test kits are rarely owned by the pond hobbyist because it’s an “all or nothing” sort of thing….. If you use well water, you don’t have chlorine. If you don’t use well water, you do have chlorine and need to take care of it before (or while) adding water to your pond. Most city systems run a chlorine content of 0.5 to 3.0 ppm, but will sometimes “flush” the systems with higher concentrations. Check with your local water authority to find out if chlorine is present in your water.

Chlorine is very deadly to fish in even very small concentrations, less than 0.5ppm. If affects the fish’s gills causing severe tissue damage. Larger fish usually die more quickly than smaller ones and at a lower ppm. Even minute quantities of chlorine can also severely damage the bacteria in your biofilter system. Often times, the disruption of the biofilter (and the resulting ammonia/nitrite spike) following the initial damage to the fish is what causes them to die 3 or 5 days after the chlorine event.

Because chlorine is a gas in solution in the water, it dissipates into the air with relative ease. Simply spraying the water from your hose through the air on it’s way to the pond will allow about half of the chlorine present to dissipate into the air. Never stick the end of the hose into the water when adding chlorinated water to the pond.

Dechlorinator chemicals are used to bind the chlorine still in the water until it dissipates naturally. We recommend using a dechlorinator added to the pond anytime you need to replenish more than 10% of the pond volume (in small ponds, 2-5% in large ones). Small additions of water to the pond need not be treated in most situations.

In a brand new pond just filled with chlorinated water, about 1/4 of the chlorine will dissipate each day. If left to sit for 5-7 days, there is no need to treat the water for chlorine.

Chloramines is a compound which contains chlorine and ammonia that is also used in some parts of the country to control bacteria in water systems. This compound also results when sodium hypo chlorite powder is added by the water department instead of chlorine gas as a water treatment method. Water companies like this compound because it remains in the solution for a LOT longer than plain chlorine.

To test for the presence of chloramines take a 5 gallon bucket of tap water and use a dechlorinator as directed. Next, test the water for ammonia. If ammonia is present, you’ve got chloramines. There are several dechlorinators on the market which will take care of both the chlorine and the ammonia. Alternatively, if you have an established biofilter, it will manage the left behind ammonia after using the less expensive plain dechlorinator to treat the water.

Fish stocking density is affected by many different variables. Larger fish require a LOT more water than smaller fish. The number of plants in your pond, the type of filtration system, and the dissolved oxygen levels in your pond affect it. The waste handling capacity of your filter system and how much of what quality food is fed plays a big role.

In other words, that’s a tough question to give a definitive answer to. Suffice it to say that it’s likely to be a whole lot fewer fish than you initially planned on getting. Most small water gardens (under 500 gallon) should stick to goldfish and avoid the much larger koi. Remember that the little fish you buy will grow FAST in a pond environment, and if too numerous, they can outpace the capacity of the filter system and result in dead fish. Besides that, within a season or two you’ll start seeing baby goldfish who will ALSO grow to full size.

In general, each adult goldfish needs at least 15-25 gallons of water and each adult koi needs 100-300 gallons or even more. Unless you plan on substantially increasing pond size and/or filtration systems, you should plan for the eventual growth of the fish and keep the numbers down. Work closely with your local pond dealer to make sure you don’t overpopulate your pond. Having a few very healthy fish who grow to attain their full color and size potential should be desirable over a whole herd of stunted sickly fish.

Adding new fish to an Existing Pond Population

Great care should be taken when purchasing a new addition to the pond. While koi and goldfish are rugged and hardy creatures, they suffer tremendously from the stress of transport to a retail facility. They usually arrive at your dealer with their immune system suppressed from the strain of transport and can be harboring deadly disease and/or parasite problems. These are things that you DON’T want to have to deal with in your pond. In particular, avoid the big super-chain stores that occasionally get large batches of fish in for cheap prices. Take note of the above info on overcrowding and picture the poor transport-stressed fish crammed 30 to a 20 gallon tank just like the tropicals………. then look closely for the ones that float or lay quite still on the gravel, they’re dead, you know!

Either buy fish from a reputable dealer who quarantines his newly arrived fish, OR, build yourself a quarantine facility and keep the new guys isolated for at least 3-4 weeks BEFORE adding them to your pond.

Some folks like to add fish of other species to their goldfish and koi ponds. Pleocostumus, or algae eater or sucker fish, are usually one of the first choices. This is usually not a good idea for several reasons. All of those other fish are tropical, and have different water temperature requirements than cold water koi and goldfish. A Pleco may do fine all summer, but it’ll die if left in the pond over winter. Besides, the only “algae” they eat is the beneficial carpet algae that grows on the bottoms and sides of the pond.

Add Only a Few Fish At A Time

Don’t add more than 1 to 3 fish to your pond at a time. Adding too many fish at once will produce more waste than the filter can convert. Allow about 10 days for the biofilter to increase it’s capacity and absorb the increased waste in the pond before adding another 1 to 3 fish.

The skimmer baskets establish the water level, house the pump and plumbing, remove floating debris, serve as biological filters, and circulate oxygenated water back to the pond.

They also protect the pump from clogging. The filter mats and debris nets are very easy to remove and service.

Plants want a definite daily light and dark cycle each day; 10-14 hours is fine; twelve hours is the duration on the equator, where many tropical plants are found.

Once a week with a normal amount of fish and plants, twice a week for a large amount of fish and plants.

We’ve found these formulas and conversion factors to be helpful!   Have Fun!!

Would you like to know how much you spend on the electricity of your pump? You may find the following formula will be helpful.

Water Quality is the most important aspect of fishkeeping there is.  Poor Quality water introduces stress in the fish and creates the right environment toxins which can ultimately cause death.