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  • Water Changes

    Ever notice how many pond environment discussions end up addressing water changes or flow-through rates? The Bakki Showers discussion keeps returning to Maeda's 10% daily flow-through. The importance of alkalinity to a thriving bio-filter becomes re-inforcement for water changes. Build-up of nitrates, hormones, pheromones, etc leads to water changes. Ph crashes becomes a discussion of water changes.

    No matter what filtration system is utilized, the goal is to minmize the deterioration of water quality that begins the moment the water is introduced to the pond. Some are fortunate to have source water that is useable without pre-treatment. Some need only de-chlorinate. Others may have sophisticated pre-treatment to eliminate a negative contaminant or to add a missing element. Once the water is introduced to the pond, we exert tremendous effort to keep it as close to that condition as we can, but it is always a losing fight. In the pond environment, water quality falls.

    I just finished reading an article encouraging 10% per week water changes wherein the author goes on to say: "... or at least twice per month." This is the advice typically given to novice koikeepers ... the folks with the least experience in filtration maintenance, the least knowledge of water parameters and the greatest tendency to over-stock, over-feed and over-medicate. Repeatedly, however, we learn of highly experienced, successful koikeepers whose water replacement routines are at a much higher level ... Maeda's 10% daily flow-through for a lightly stocked, heavily filtered pond is just one example. The Japanese magazines are full of profiles of hobbyists at the top level who use continuous flow-through of that much or more. JR has shared his routine of multiple changes each week, with daily small changes through settlement discharge. Others have very similar practices. So, we find the elite of koikeepers generally performing far greater water changes than is recommended to novices ... the people who know the most and have the most sophisticated systems do more.

    Sometime ago, somebody suggested water changes to improve fish survival rates. I suspect it was at the turn of the 20th century, when "science" and concepts of natural balance began to influence Victorian proclivities to possess and display nature in the parlor. Too many dead goldfish, minnows and exotic paradise fish rotting in a bowl for things to stay the same. Why 10% was suggested, I do not know. I suspect it was an amount that did not sound like too much work and was not so great as to shock captive fish that were weak. However it came about, the standard of 10% per week has endured. I think it terible advice.

    At 10% per week, contaminant levels in the water will continue to build for a period of over 30 weeks before equilibrium is reached. [If it is ever reached.] Solid wastes may be removed mechanically or through settlement, but the non-solid wastes continue to be added and they "rot" in their own ways, whether it is through build-up of nitrates or decomposition of micro particles or dissolved organics. Hormones will impede growth. Immune systems are impaired. Excretion of waste chemicals through the gills and skin is less efficient. So, we tell newbies to do 10% per week, while the experienced among us do far more. They are the ones who need extra margins. It is the highly experienced who can race closer to the line.

    But the highly experienced know better than to go close to the margin of their fish endurance capacity. They know the unexpected will occur, and that extra margins of safety (i.e., water quality) is essential.

    Well, I've ranted enough. Think about it when next you advise the newcomer.
  • #2

    All good points Mike, but think about what the reaction would be from most of our own club members if at our next meeting either one of us get up and tell them that they should be exchanging 20%, 30% or 50% of their pond water each week. They already think I am a fanatic for doing two 15-20% water changes per week (well, the label fanatic came from that and the many other extremes I tell them about). I think for the average Koi owner, you would be lucky to get them to do a 10% water change each week. The amount of water changes performed is different depending on what your goals are. If you are trying to raise show Koi, then the frequent water changes are a small price/effort to pay. For the Koi owners that just like having some pretty little fish in their backyard, they see it as a waste of water.

    Do you hear the comment I got from a long time member after my presentation on water testing? "If I have to test the water every week, I wouldn't want to have a pond. It's too much work."

    Tell a newbie, minimum of 10% per week. Then when they ask why their Koi are not growing as well as mine, one of the many reasons I give them is they need to change more water.

    Orlando, FL


    • #3

      Yep. You're right about how people react. But, then they will turn around and spend on every cure that gets sold when their koi gets ill. People always seem more willing to spend on cures than on prevention. We know situations where fish have not grown in years or where there always seems to be one problem or another that is getting treated, just finished being treated, or going to start treating soon. That's a lot of work!

      Water costs will vary. So, the economics will be quite different from one area to another. I consider myself lucky because I have a separate meter for irrigation to avoid the local sewer tax, and that one time charge paid for itself long ago. Still, I do spend hundreds on water for the pond each year. But other than the massacre when the current pond went through its new pond syndrome 2 years ago, I've not had a koi die for nearly 5 years. They grow well. I go a bit nuts over any symptom (as you know from my panic calls), but other than ich last winter, no parasite issues in 18 months. I've never had an aeromonas infection on a koi owned more than 60 days. My filtration system could use all sorts of improvements. It is sure a long way from a "proper koi pond". But regular large water changes are what saves me. ..... and are a lot cheaper than losing my best fish ... and no price equals that home bred 9 year old hariwake nobody with a proper pond would want. Any way, I'm preaching to the choir.

      The hard part is when I see a situation that needs to be addressed, but I don't want to hurt feelings by being critical. So, my silence becomes a form of hypocrisy. Then I get angry with myself ... and then I rant like I'm doing again tonight. But, it feels better to vent a bit.


      • #4


        At least 80% of the local ponders in my area do not use dechlorination with a water exchange using city chlorinated water. So if they exchanged 40% of their water every week, the fish would eventually die of chlorine poisioning. As it is, I believe the only reason they get by without dechlorinator is that their ponds are so dirty that the chlorine immediately reacts with the high DOC content to avoid fish deaths. At koi club meetings, I hear them all agree with each other that just adding the water to the pond by spraying it into the air dechlorinates the fresh city tap water.....yet somehow their fish seem to survive, it amazes me at times.

        Okay, it may be a bit off the topic you are discussing here, but as long as we are talking about advice to newbies, I thought I would mention this local water change "folk art" to see if anyone else has this frustration.


        • #5

          I have read several times on the boards where hobbyists claim that spraying the water into the pond releases the chlorine. Since ST is so cheap, I have always used it thus never tested the results of spraying water. I'll have to test that tonight and dig up the dechlorination article I wrote several years ago for our club newsletter. It's about time for a reprint and include the results of that test.

          Roddy, I am sure you have either already tested that myth or have some science to debunk it. Care to share?

          Also, what is the actual ratio of ST to chlorine to effectively render it harmless to fish? I know you have posted it in the past. I mix up a 13% solution and apply 1oz per 100 gallons of tap water. I had been told that the 13% solution would treat 300 gallons of water with 1ppm chlorine (in my tests that seemed to hold up). Since my tap water ranges between 1ppm and 3ppm depending on the time of year, I always lean towards using more than less.

          Orlando, FL


          • #6

            Roddy: That's a good reason to only do 10%! :lol: Dechlorinator is so cheap I too fail to comprehend why anyone would take risks to avoid the small cost. In the U.S. additive-free sodium thiosulphate (sp???) can be obtained from AES or mail order aquaria supply houses in quart and gallon sizes pre-mixed, or in dry form very cheaply.

            Curious that someone would take the extra time involved in spraying the replacement water, but not spend pennies on dechlor. Of course, bet they end up not spraying most of the time, since none of the fish looked sick last time they sprayed they can push it a bit more.

            The attitude that koikeeping (and fishkeeping generally) is about how close to the edge a fish can be pushed without dying is the fundamental problem. People who do it that way would not do the same to their pet dogs and cats ... "she didn't get sick when she slept in her feces last week." Oh well, educate, educate, educate.


            • #7

              City Water

              Yes, definitely, city water (chlorine or chloramine) is a big contributor to problems,... ongoing gill damage,... pond eco-systems constantly out of balance,... leading to other Koi health issues, and pond issues - I remember a "seasoned" Koi keeper once telling me that she doesn't dechlorinate because the chlorine helps kill the "bad bugs" in her pond, she was speaking of flukes, costia, etc.

              I can think of several recent incidents in which the Koi keeper forgot to turn off the city water resulting in chlorine poisoning of the entire ponds,... including a pond with Grand Champions,...

              Ideally, Koi keepers with city water should have a 1000 gallon "stock tank" storage tank with an auto-fill valve and a shut-off valve (somewhere handy, such as in the garage, or outside out of sight) - so they can fill this 1000 gallon tank up with city water, dechlorinate it, then refill their pond with this precisely measured dechlorinated water, then shut the valve off, and let the tank refill itself, dechlorinate that batch, and have it ready for the next water change. This will prevent chlorine accidents, and give you the exact amount of water you've just changed - for a 10,000 gallon pond, you've just changed 1/10th or 10%,... per week, pewr day, or whatever your schedule. This stock tank should also be aerated with a big airstone to ensure even distribution of de-chlor, and for general aeration of the new water.

              Best Wishes,
              Brady Brandwood


              • #8


                Henry, I will do the math and write another reply to this thread on the specifics of dechlorination with sodium thiosulfate. Right now, I just want to rant on this subject for a few minutes instead, saying those things that need to be said to orient us on this subject.

                On the Water Gardening board, the most prominent posters often state there is no need for dechlorination with water exchanges, and most of them openly write on that board how their fish thrive through large water changes without dechlorination. One specific poster, who puts up pictures of their fish every week of the year on that board, even states they exchange ~ 30% of the water weekly in the pond system during Summer months without dechlorination, using city water, making a small water exchange every day without dechlorination. So the practice is not isolated to the mountain folk of "West By God Virginia" "Country Roads" territory. After interacting with those particular folks on the Water Gardening board for a year or so, I gave up trying to persuade them to use dechlorinator, and instead cautioned them that changing that much water without dechlorination should only be done in Summer months when there is enough DOC to "eat" the chlorine immediately.

                The process of DOC "eating" chlorine is the same process as DOC "eating" a potassium permanganate charge. Surely some of you have used potassium permanganate in a "dirty" pond somewhere in your ponding experience to see a significant PP charge dissappear in less than 15 minutes after it is charged. That is because the water was dirty enough with enough DOC content for the potassium permanganate to rapidly be used up. The same thing happens to chlorine. If the ORP (Oxidation Reduction Potential) of the pond measures below 200 millivolts, adding fresh water without dechlorinator is unlikely to kill the fish since the chlorine or chloramine will be almost immediately consumed. But if it is a clean pond with an ORP reading above 325, adding a significant water exchange using city water is very likely to either kill the fish or do real harm to the gills. Fresh tap water usually is an ORP reading ~ 500 or so from the chlorine or chloramine oxidizer present to provide the oxidation potential. My swimming pool water routinely runs an ORP reading of ~700 millivolts from the 2 to 5 ppm chlorine content I maintain in the swimming pool. Any ORP reading in excess of 500 is likely to kill the fish if it lasts for more than a few hours.

                I was called to one local pond a couple of years ago with dying fish. I tested all the "normal" water parameters, and everything checked perfectly. I checked the fish, no parasites I could find. So I started asking questions about the history of the pond. The pond had been emptied for the Winter after all the fish had been killed the previous fall, the gardener for the estate had left a hose running in the pond overflowing it for 24 hours without dechlorinator. The pond had been filled with city water in the Spring, no dechlorinator. The filter system had been turned on, which consisted of a large fountain lava rock trickle tower filter in the middle of the pond with recirculation from a submersible pump. After running the water for three weeks through the fountain with high aeration, it was assumed the chlorine was gone and excess koi from the son's pond had been added (the son of the lady lives a few houses down the street from me). The fish started dying after about a week in the pond, no fresh water had been added. So I measured for chlorine content and found a reading of 1 ppm chlorine residual after a months recirculation, the same as fresh city water. The problem was that the pond started sparkling clean, no plants, nothing to "eat" the chlorine. So after a month of aeration, sunlight, and so on, the chlorine was never reacted away, and slowly killed some of the fish. I added dechlorinator, no more fish died.

                Likewise, the chlorine in my swimming pool is stable for weeks to months in the Spring or late Fall when no one is swimming in it, and no leaves are falling into it, but the swimming pool needs frequent chlorine additions when the leaf fall is high creating DOC to eat the chlorine content of the water. Likewise, my outdoor koi pond directly under the leaf fall of a large oak tree needs frequent low level (0.2 PPPM!) PP treatments to eat the DOC content in the high leaf fall season to maintain high water quality, but runs ORP readings in the 300 to 400 range without PP treatment the rest of the year. Chlorine and PP are the same chemical and the same effect on the water and the fish, both are strong oxidizers which react immediately with significant DOC content.

                There are several points to my post here:

                1. If there is nothing for the chlorine (or PP!) to react with, it will be there indefinitely to kill the fish. Neither sunlight nor air will have a significant effect on the chlorine content.

                2. Most ponds of "newbies" and "water gardeners" are dirty enough to use up the chlorine in city water in minutes to get by without dechlorination.

                3. The "newbies" and "water gardeners" do not understand what they are doing and how it works sufficiently to avoid killing all their fish eventually. This is GOOD for folks who sell fish, and BAD for those of us who are trying to educate them that those practices can be dangerous.

                4. Don't waste your breath and typing skills trying to get most of these "water gardening" folks to "do it differently", all you will normally get is hostility from most of them when you try to educate them to the possible errors of their routine practices. Kind of like trying to say some of the practices at USA koi shows should be rethought in the middle of KHV spreading around.....keep it to yourself, no one wants to hear anything they do could be improved.....LOL


                • #9


                  Brady, I would expect "just the right process" could successfully use the chlorine in city water to kill parasites just as "just the right PP process" is used by some experienced ponders to kill parasites. However, I don't think any of us want to do the research to show exactly how to do it that way. Technically, it can work, both chlorine and PP can oxidize the parasites without oxidizing the gills of the fish when "in perfect control", monitored by a calibrated ORP meter, for a specified length of time. Maybe that experienced ponder had worked out just how to do that in their system, and could educate the rest of us in how it works......


                  • #10


                    might make for whiter whites in the fish as well!
                    " I'd rather a bottle in front of me than a frontal lobotomy "


                    • #11


                      I just glanced through this post I don't think any one mentioned a big problem regarding water changes. Many people may never use dechlor when doing a water change and because they have always done it that way think they will be ok. The problem is sytems malfunction from time to time and the treatment plant may overdose the normal amount of chlorine or switch to chloramines and then it becomes a problem.
                      Last year our local water plant's dosing pump failed :shock: and dumped a 55 gal barrel of pp in the system all at once. ( People a mile from the plant had pink water. ) My point is that this could and does happen with chlorine and although if the concentration is quite high you may not have added enough delchor in the system to handle it totally, but you would be much better off than not having added any dechlor at all.
                      Gee I'm glad we have a well.


                      • #12


                        A well is in many areas may be the best source for adding water. Even if you have city water for the house; just think of the savings on the house supply as far as conserving drinking water supply versus where you can tap into groundwater... I can't remember who but someone has a seperate meter for gardening water and pond use and pays 900 a year for the water. I wonder the cost of sinking a new seperate well for pond and irrigation use? There is the electric bill to deal w/ but that can't be as bad as buyuing water.
                        " I'd rather a bottle in front of me than a frontal lobotomy "


                        • #13

                          "Bore Hole"

                          The "average" price for a well, drilled to 180 feet, with pump, storage tank, & hook-up is around $3000,... here in the Southern US. An excellent envestment for happy Koi!

                          Best Wishes,
                          Brady Brandwood


                          • #14

                            Hi Mike,
                            We just sank our well 2 Februarys ago to the tune of about 6K. They were going to stop at around 306 feet and I made them go another 50 feet. (They keep building houses around here, water table keeps dropping and if I didn't have water changes to do we could have gotten by with our old well - I think). :roll:
                            Of course you have the issue of low oxygen in wells, but that's no biggie.


                            • #15


                              Do you put the water in straight from the pump or do you settle or treat it first?

                              Koi keeping is not a belief system; it is applied science with a touch of artistry.


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