Black Tuesday at the Koi pond.

In the last few posts I have talked about losing some fish and the challenges of fighting diseases in a pond.  This makes it a risky time in any pond, but more so when the temperature is changing.  Two fish have died (Rhu and Patty) and the disease has progressed to others in the pond (Tawney).

Summer is also a time of vacations and travel.  Traveling while treatment is progressing is also very risky.  Treatments usually occur over many days and things can change wildly over that time.  Symptoms can worsen and new symptoms may appear which may require changes in your treatment plan, all the while you are gone.  Plus putting such pressure on friends or neighbors who are feeding the fish is just not right, or productive. Unless they are familiar with Koi, they will not be in a  position to help with the treatment process.

At the Koi Garden pond we had just that happen:  a vacation was planned for a long time and I had to leave with a treatment plan partially completed.  The other thing that complicated matters is a heat wave in Seattle that raised the temperature over 90 degrees.   The higher temperature changes the water chemicals very quickly and can cause additional problems.  The treatment did not go as I had planned or wanted.   We had enlisted friends to review and feed the fish while we were gone.  But the higher temperature caused green water which obstructed any views of the fish, so health problems could progress…  Because they could not see the fish, they assumed that things were hunky dory.

Not so much.

Returning from a week long vacation to find all the fish dead is a bad way to return home.  

This is a sad time at the Koi Garden.  I will have to spend some time thinking about how to progress with the pond.

RIP Koi Garden Fish....

Black Day at the pond

We had two important tasks to accomplish:  Watch and help Patty through the treatment plan; and making sure the rest of the pond did not go the same path as with Patty. 

Patty initially appeared to respond well to the Malachite Green, but it was a short-lived victory.  Applying medicine to a hospital tank is tough.  The medicines need to be applied to a small space, so the correct calculations must be made.  Also since the medicines are so strong and the fish is so weakened by disease, the fish may not be able to survive the treatment.  And that is what happened to Patty.  After a short time in the hospital tank, Patty succumbed to the disease.  The disease had progressed too far.  Despite direct intervention of moving the fish forward and backward to keep water flowing through the gills, I was not able to revive Patty and keep the fish alive. 

No time to grieve.  Losing Patty was terrible, but there is no time to waste.  The rest of the fish we exposed to Patty for a few days before I found and moved the fish into the hospital tank.  This means that the pond and the fish that live there are at risk and must be treated very quickly.

While Patty’s treatment was progressing, I took some time to get a good look at the rest of the fish in the pond.  Things to look for include fish color, movement, feeding, anything out of the ordinary that hints that the fish might be ailing.  In the Koi garden pond, the rest of the fish were doing fine with the exception of Tawney, the long fined Tancho Showa.  Tawney was sulking on one side of the pond, not swimming with the rest of the fish.  There was no visible fin rot, but when fish do not fight for food with the other fish, there is a problem; and judging from what happened to Patty, Tawney had a BIG problem. 

Since the pond needed to be treated, I decided to treat the whole pond with the fish inside it.  I removed the plants to make sure they did not interact with the medicines.  This could be a problem for both the plants and the fish.  Plus, once the treatment plan is completed, we will place the plants back in the pond again.  I applied the Malachite Green to the pond (with 1 ounce per 500 gallons, dosed daily).  I also turned the heater way up in the pond, almost to the maximum.  Normally, I would never need to heat the pond in July, but this summer has not been normal.  I had turned the temperature off because I had thought summer had arrived.  But when the problems arrived, the temperature had dropped to 55 degrees.  At that temperature, the fish’s immune system is working, but not as well as it would be at 75 degrees.  These items seemed to help; there was a visible reaction within a half hour.  They all started being more active, looking for food and swimming around more.  Based on this outcome, I will keep the temperature slowly increasing until it gets over at least 70 degrees.

All fingers and extremities crossed!!!!

Patty is found!!!!!

Patty was hiding at the bottom of the Koi Garden pond.  I was worried that Patty was eaten by one of the critters that frequent the garden.   Luckily, that was not the outcome of the Patty search.  I found Patty along the bottom of the pond, hiding among the pumps and plants. 

But all is not well. A lethargic fish is not a healthy fish.  And Patty was lethargically hiding at the bottom. 

No feeding.

No swimming.

A little bit of rot on the long flowing fins.

And a very stressed pink color.

All indications of a very bad situation. 

I immediately sprung to action.

First step is to get the fish out of the pond and into a hospital tank where intense treatment can be applied.  In Patty’s case, it is quite easy to catch a sick fish with a net.  They don’t move fast and are really not feeling well.

The hospital tank, in this case, was a large bucket with an air pump, bubbling constantly.

I quickly look at my Koi reference books to try and get a feel what the offending sickness.  I use my favorite book for koi knowledge(The Tetra Encyclopedia of KOI).  The fin rot indicates that bacteria is eating away the long flowing fins.  The pink color indicates stress and sickness on the white fish.  I added Malachite Green to the water.  It is a mixture of formalin (think formaldehyde, icchhh) and some chemical that produces bright blue stains (OK, I have no idea why it is called Malachite Green….).  This chemical kills any exterior bacteria that are attaching the fins. 

It is also a good habit to call your Koi network to confirm treatment.  For me, I call Diane Torgeson of Oasis Water Gardens.  Diane confirmed the Malachite Green treatment but also warned me NOT to use salt water treatment at the same time.  Whew, I use saltwater treatment for a general treatment.  It improves functioning of Koi gills and assists the koi’s natural defenses by increasing the slick feel of the fish, restricting bacteria’s ability to get to the fish.  But in combination with Malachite Green, the salt water will burn the fish;  Ohhhh No…  Dianne also recommended additional treatment with antibiotics.  Both of these treatments are multi day treatments.  The Malachite is applied each day for at least 3 and possible more days.  The treatment plan for the antibiotics is a 10 day plan, with drugs applied to the hospital tank every day.

With the correct treatment plan in place, I embarked on the toughest part of any hospital stay:  the waiting….

A death in the Koi Garden

Spring is a risky time in the Koi Garden.  The water temperature rises and with that, so does the risks for the fish.  While rising temperatures allow internal immune systems to take hold, it also allows viruses and harmful bacteria to grow and flourish as well.  In some cases the harmful bacteria grows faster than the fish’s ability to fight them.  This can lead to diseases and even quick deaths.

This is what has happened to some favorites in the Koi Garden.  Rhu, a great looking Kumonru died very quickly this week.  One morning he was found dead in the pond. Cause unknown.  Call it Spring Fever.   A great loss. Rhu was introduced to our readers in previous posts and will he will be missed.

When dead fish are found in the pond it is very important to remove the fish very quickly to reduce the chance of any disease transferring to the other fish.  A detailed review and analysis of the dead fish must be made to get some idea of the problem.   Do not touch the fish with bare hands.  Gloves should be worn; gardening gloves work well for this task; and they should be thoroughly washed afterward.  The fins should be checked for any problems like fin rot, ich, or any other malady.  Pry open the gills; the color should be a nice reddish, pink color.  The gills should be complete and healthy looking.  If the gills are damaged in any way, it could be an indication of the disease that the fish succumbed to.   It is also very important to test the water as well.  Watch out for high levels of Ammonia and Nitrites.  They can stress the fish and extended periods of stress can cause death.

This is the time where good reference materials are a must.  In previous posts, I have talked about a favorite book of mine.  In my gift recommendations I have talked about a few good books that could be a great help.  This is the time to talk to your Koi gardens friends.  In the Koi Garden one great resource I have is Oasis Water Gardens.  Diane Torgenson is a great source of assistance to any problems I might have.

In the case of Rhu, it might be of interest that the fish did change color.  It was almost not possible to recognize Rhu.  Readers might remember that a Kumonru is a fish that can change color based on temperature, water chemicals, and other factors.  When I pulled Rhu out of the pond he had a lot larger amount of red coloring, far more than he normally had.

Rhu was placed to rest with a burial in a corner of the Koi garden.  It is the same area where I have placed other fish that have died in the past.   While I never like to lose fish, having them give nutrients and growth to a nice Hydrangea is at least something positive out of the whole thing.

Hibernation is not in the cards!!!

We are in the midst of a mid winter thaw or an early spring.  It really makes no difference which as either way it has a great effect on the Koi Garden.  First it was the Crocuses....  Really gorgeous ones, they are just too early.

Next it was the Cherry trees and their blossoms.

The cherry trees are blooming very early, in fact most are already dropping their petals.  Now even the earliest of the Magnolia trees, the Starlota is already in full bloom. 

 Definitely not your typical Koi Garden in February. 

But there is a negative side to all this great weather.  Pollen counts have risen precariously; and with it come the allergies.   Allergies affect the Koi Garden guy, but I am guessing that the fish don’t suffer from the same malady (at least I have received no requests from the Koi for Benadryl).  But there are some negative aspects of the early warm weather on the Koi Garden.  The pond water that was green most of the year, has never really gotten cold enough, long enough, to kill all the algae and clear up.  Therefore the water has stayed green, maybe even gotten more so instead of a normal winter where the cold water clears up all the algae. 

Checking the water chemical levels is not something I bother to do too often in the winter, but with the spring temperatures and green water, I figure I had better do so.   After checking with the test strips, only the Nitrates appear high.  Since the Nitrites and Ammonia are not high I am less worried about the high Nitrates.  A higher Nitrate indicator essentially means that plants would do well in the water.  Well, Algae is a plant and I already know it is doing really well, too well; hence the problem.  If the rest of the chemicals levels are good, the green water is not a show stopper problem, but what good are fish if you cannot see them???

Hmmmm, Decisions about UV lights will have to be made.  Turn it on too soon for too long and the UV light will kill the algae and cause Ammonia levels to increase to hazardous levels for the fish.  Do nothing and the green water means you cannot see any of your fish.  Decisions, decisions…

The water temperature is now near 50 degrees.  If this is true, I will have to start thinking about feeding the fish as they will no longer be dormant and will be hungry!  Normally these are issues we deal with in April, not late February or early March.  Previous testing indicated to me that the water temperature indicator runs about 5 degree too high.  This means I will hold off feeding the fish for a little longer.   I may even turn on the filter heater if the pond temperature starts fluctuating each day.  

So much for the long dormant winter…..

It’s almost time to fall back, but not into the pond

Just like with clocks, there are some things that must be done each year at the Koi Garden Pond. As the temperatures drop, both in the water and in the air, the plants will start to change color and die back. The water will begin to change as well losing the algae that cause the green color and will eventually become clearer. In addition to the changes inside the pond, the leaves in all the adjoining trees are changing color and will start to fall into the pond.

This is an important time for the pond. The dropping leaves and die back of the pond plants can introduce a lot of biomass into the pond in a short period of time, putting real stress on the Nitrogen cycle. As we talked about in earlier posts, this can really screw up the chemicals of the Koi pond. And one thing you cannot mess with is my chemicals in the pond, not after the work we have done to get them in order…

Face it, cutting back the existing pond plants will just sort of speed up what was going to happen anyway and allows us a way to keep the plants from decaying in the pond. We have already gotten the benefits of the plants, both visually and with respect to pond health. It only goes downhill from here… at least till next spring. Trimming the pond plants back also allows me access to any gardening and repotting needs. Lilies are notorious for outgrowing their pots. They are also a very easy plant to break up and split into multiple pots. And as any aficionado of Japanese gardens knows, you cannot ever have enough lilies…

Once we have cut all the pond plants back and or done any required repotting, we can place them back in the pond. They go dormant and will do just fine in the water during the winter. Now we can place the pond cover over the pond. This will not only keep the falling leaves out of the pond, but also keep any Koi-hungry predators from getting at the Koi.

At this time, it could also make sense to do a partial water change. This gives the pond a bump start in cleaning up the water. As the water temperature drops, the algae that makes up the green water, will start to die back. By manually reducing the algae, we are reducing the possibility that large amounts of dying algae will cause a spike in Ammonia and we have already talked about the evils of Ammonia and the Nitrogen cycle… The water is also very high in nutrients. So reserve it for your favorite plants!

Ammonia is for cleaning, not Koi ponds.

Every week or less I perform water tests on the Koi Garden pond. This test includes three basic tests. Depending on the results of those tests, I might do some additional more extensive testing. I normally do testing with chemical droplets applied to a sample taken from the pond. Depending on the test, up to two different sets of drops may need to be applied along with a regimen of mixing and waiting. The resultant mixture is color compared to key cards included in the tests. Based on the color key, some action may be required: change of water, addition of some chemicals, etc. I am also trying a new type of test I found at Lowes (Lowes.com). It is a strip of paper with the testing mediums for all the tests painted on the each paper. The paper is dipped in the pond water and then reviewed against a key for color changes. The strips include tests for Nitrate and Nitrite, including pH and water hardness. Despite the absence of a direct Ammonia test on these strips, the convenience alone makes them desirable. In the tests I performed, the strips appeared to get the same results as the chemical drops.


Based on these most recent tests, I got some responses that required an action. But before we discuss the failed test, some background is required. The key to the biological filter is the nitrogen cycle. See below for a figure of the nitrogen cycle (diagram below). Ammonia results from the decomposing Koi waste and any other biological matter that gathers and decays in the pond. Beneficial bacteria called Nitrosomonas converts the Ammonia into Nitrites. Nitrites are converted to Nitrates by a different bacteria called Nitrobacter. Additional beneficial bacteria ingest Nitrates to fully clean the water. Knowledge of this nitrogen cycle and the correct interpretation of the test results allow a person to respond correctly to clean your pond.



When I applied this series of tests to the Koi Garden pond, I got an indication of higher levels of Ammonia than were warranted. In new ponds and ponds at the beginning of the warmer season, it is common to see some Ammonia responses on tests. These indications should reduce or go away fairly quickly as the beneficial bacteria grow. It may take up to 4-6 weeks to get all the beneficial bacteria growing in your filters. In my last tests, I had very low Ammonia, and progressively higher Nitrites and Nitrates. This indicates that the biological filter was “moving through the Nitrate cycle”. To have the Ammonia levels increase rather than decrease indicates that the amount of the particular beneficial bacteria was decreasing rather than increasing or remaining stable.

There are two actions that must be taken:
One, immediately reduce the level of Ammonia in the Koi Garden pond; Two, remove the cause of the increase of Ammonia levels.
1) The best way to quickly remove the Ammonia from the pond is partial water changes. Change 20 to 30% of the pond water and replace it with clean water. The addition of salt to the pond water and having a ph outside the range of 6.8-7.5 can both reduce the toxicity of the Ammonia. Salt should not exceed .2% in a pond but in a bath can go to .3%.
2) Removing the cause of the increased Ammonia is a more complex issue. There could be a number of causes for increased Ammonia. A rapid increase in food, sunlight, an increase in degrading biomass in the pond, an increase in the number of Koi in the pond, and a decrease in the number of beneficial bacteria are all possible causes for increases in Ammonia. In the Koi Garden pond, no additional fish or increased food amounts were introduced. I did not think the amount of leaves in the base of the pond were significant enough for the Ammonia I was measuring. I may have inadvertently increased the dead material as an outgrowth of killing the algae. In a future blog, I will write up discussions about adding plants to a pool and also a tool that works as a great cleaning device.

In previous blog entries I had discussed the green water or algae we had in the pond। To counter the algae, I turned the UV filter on. In a few days the green water was gone. The UV light sterilizes any live organic material in the water so it would have killed the algae and it would have dropped to the pond floor or end up in the filter where it would have acted like any other dead organic material. Pond hygiene is a solution to this problem. This could have added to the Ammonia in the pond. The UV filter might have caused the Ammonia situation to be worse in another way as well. The UV light will not only sterilize algae but it will also sterilize beneficial bacteria suspended in the water. Most of the time, beneficial bacteria introduced into a pond will eventually find a home in the filter medium or attach itself to the pond wall. But newly introduced bacteria will remain suspended in the water for a while and will, if it passes through the UV filter, get sterilized by the UV light. If I had not waited enough time after introduction of beneficial bacteria to the time when I turned the UV filter on, I could have reduced the amount of beneficial bacteria. The solution to this would be to turn off the UV filter whenever I introduce beneficial bacteria to the pond.

It's all becoming clear to me

Last week the Koi Garden pond was a thick and dark pea soup. It was difficult to see the fish at the surface much less when they were submerged near the bottom of the pond.

I then turned on the UV filter.
The UV filter does not work in minutes but it does work.

UV filter setup
The water is pulled into the system via a submersible pump at the far end of the pond. It pulls water through a smaller filter assembly. This filter stops leaves and debris from entering but also has enough filter medium to allow for some biological filtering to take place. The water is then split up into two paths. One path goes directly to the larger biological filter outside the pond. The other path goes through the UV filter and then is returned to the pond via a Venturi tube.

This setup has a number of benefits.

First it allows for some water to reach the exterior filter WITHOUT going through the UV filter. This means that some water will not encounter the UV light and its sterilizing capabilities. This is good. Remember, there is beneficial bacteria suspended in the water that you don’t want to diminish, and the UV light’s sterilizing capabilities does have a negative effect on that bacteria in addition to the algae that makes up the pea soup.

Second, by splitting the water paths, it has the effect of slowing down the water that goes through either filter. This allows the UV light and it’s sterilizing effects more of a chance to have an effect on the water. It allows the UV light more time to sterilize the algae suspended in the water. In the other path, it also allows the water going through the biological filter more time to come in contact with the beneficial bacteria and clear the water.

So after being turned on for 4 or 5 days the water clears up quite nicely. The algae which causes the green water is killed via the sterilizing power of the UV filter. Make sure you test the water both before and after using the UV filter. The algae will feed on the ammonia produced by the fish waste. The UV light will also kill beneficial bacteria as well as the algae. So while the UV filters clear the water up to cristal clear levels, they also might cause increases in the ammonia levels, and therefore Nitrate and Nitrite levels as well.

Pea Soup anyone?

Every spring it comes. And every spring we come up with more tools to fight it. That green, algae filled water that restricts us from seeing the beautiful fish we pamper so much.

I have a nice UV light that will sterilize the water and keep the single cell algae in check very well. The UV light is positioned in the pond in between the in pool filter and the large exterior filter. The UV light is positioned so that only half of the water going to the filter goes through the UV filter, the rest goes directly to the exterior filter. This setup guarantees that the UV light will not sterilize all the water and kill all the bacteria in the water and the filters.

I do not have the filter on all year. I leave the UV light off for the winter and the beginning of the spring. I didn’t want to do anything to reduce the amount of beneficial bacteria in the water until the bacteria filters are up and running. I don’t mind green water for the beginning of the warmer season.

Green water in itself is not an indication of a problem. It could just be that your biological filter is not functioning yet. It is however, very important that you check the water often. You should check for Ammonia, Nitrates and Nitrites. It is also important to check the water PH level; it should be between 7 and 8. Also make sure that the Oxygen levels of the water are high. If you have lowered your waterfalls for the winter, it is time to increase the flow and oxygenation. I think that you should also turn on any Venturi tubes you may have in your pond to get the frothy Oxygen flows.

If any of the measurements are too high, you should remove 1/4 or 1/3 of the water and replace it with new water. Please note that if you do use salt, check and adjust your salt amount after you make any additions of new water.

Winter is Back!!

Winter is back.
It is not fair. People in Seattle are not used to lots of snow. And I think end of February is too late to have lots of snow and cold temperatures. But this year, we have.

I have had to decide whether to turn on the filter heater again and again. It also didn’t help that the temperature gauge broke. . Oh well, off to support the local Koi shop.

Also it is good to keep an extra eye on the Koi to see if any problems are occurring. I have a few long finned Koi and sometimes one or two of them seem to get more problems with the fins. If the fins are showing signs of getting frayed or being eaten you may need to deal with it. It could be a number of things. You should perform a complete set of water tests. I also use Salt added to the pond to help out. Salt takes some stress off of the fish by making their systems work more efficiently. It also irritates their scales and increases the slimy covering on the scales. This covering helps protect the fins from what was causing trouble with their fins.

Winter has arrived

Well the freezing weather and snow has arrived.
The cold weather that hit Seattle recently has gotten so cold, I was concerned about the filter freezing over and the ceramic container breaking. I had recently turned off the filter heater and this cold snap was enough to make me turn it back on. At these temperatures, it is not strong enough to raise the water temp too much, just enough to keep the filter and the pond from freezing over.




The water stays cold enough to freeze on the screen, making some very nice icicles. The fish are visible and moving around in the water. At these temperatures, they are sensitive to noise and harassment. The fish sometimes even lay down and sleep. I have thought more than once that one of them was dead, but the fish were just sleeping.

The screen fills up with snow as well which makes for some nice photos.




Notes for Photographers: When photographing in snowy times like this, sometimes you need to modify the photos with software. I use Picasa from google (Google.com). It allows me to lighten the photographs to compensate for the cloudy, snowy weather. Picasa allows for many more, quite complex types of improvements to the digital photos. And it is available for a nice price... Free.

December winter prep

Even as the temperatures drop
into the 30s, the Koi Garden
still teems with life.

An early morning walk through
the garden allows time and
the light to find some small,
busy neighbors.










The winter die back allows for the Koi Garden to shine in other ways. It does make the fall/winter cleaning worthwhile.


In the northwest, filter temperature is a constant problem. I use a small aquarium heater placed inside the filter assembly to help keep the filter working.


The heater keeps the temperature above 50 degrees, measured in the pond at the alternate corner. This allows the fish to feed earlier in the spring and longer into the fall/winter. Koi go dormant at temperatures under 40 degrees and should stop feeding under 50 degrees. When the temperature bounces over and under that 50 degree level and you are still feeding your fish, there is a chance that the Koi will not be able to process the food, thereby getting very sick. By using a heater, you can help remove this risk as the transition through feeding and letting the fish go dormant a lot easier. Also, in the spring, as the temperature is rising again, the harmful bacteria and viruses wake up from dormancy faster than a Koi's imune system. Having a filter heater can help make the transision from 30s and 40 to over 50 a lot smoother.
It also allows the filter to remain at a higher temperature allowing the beneficial bacteria to work more efficiently. Since the pond temperature is now falling close to 50 degrees and the outside temperature is mostly well below it, it is time to turn the heater off for the winter. The Koi will be fine as long as the pond doesn't completely freeze over.
I prefer to turn the heater off at the plug in, rather than remove it from the filter. This allows me the option of turning the heater on for a few days if the pond start freezing over in a cold snap.

In preparation for the winter, I also put the winter screen on the pond. It is a wood framed monstrosity that has a metal screen that I built a few years ago. This allows light and all the elements like rain to get through, while keeping the raccoon away. I don’t use this screen in the summer or while I am around and enjoying the Koi Garden, but in the winter, it is a nice way of keeping predators at bay.