It is very tempting to take up the challenge of creating a closed system in which the water, benefitted by unending and created filtration treatment, will never need to have water changed. But like turning lead into gold, no one has ever been able to realize this fantasy in real life.

Living creatures ‘impact’ their environment and our koi are no exception. Some of you may remember when Jmat was made out of ‘horse hair’ ( actually other organic fibers) and how long that material lasted once bacteria settled on and began breaking it down. And we all know of the power of water and bacteria to dissolve all material it comes in contact with- rusting, eroding, metabolizing.

Our koi and associated microbes will, over time, add ‘things’ to a fixed body of water and ‘take things’ or use things up within that water. And the ever changing water will then impact the internal workings of the koi, who are separated from their watery environment by only a few layers of cells located at the ‘gateway’ - IE the gills. So like a submarine with a screen door, the gills must deal with the building metabolites both inside itself and immediately outside it’s body. And of course, a koi is subject to the pesky laws of osmosis and diffusion.

One of the rapidly building waste products produced by koi in large, ever building quantities, is phosphate. Today’s koi foods are LOADED with lots of essentials. And today’s koi owners feed lots of koi food! Not all this material can be utilized by the koi on an hour to hour bases and much of the packed nutrition and mineral content is simply passed out of the koi for bacteria to deal with in a process known as mineralization. These bacteria then use the ammonia or hand it off to the nitrifiers that we are all familiar with. But this is a process and some stages will take some time. And during that time, building nitrogenous materials like nitrate and residuals like phosphate will increase. All of this results in a high bacteria count, shifting water chemistry ( pH, hardness) and loss of oxygen ( ORP decline). Great heroics can be applied to try and stay ahead of this dynamic but the trend line is clear- the water is becoming polluted and burdened and at the same time, it is losing its proper gas saturation ratio and it’s typical buffering capacity.

The solution? Use band-aids so as to ‘properly manage an over stocked pond’. Do what I call ‘ chasing the parameters’ by adding gadget upon gadget in an attempt to manage excess and sequential changes in nitrogenous waste material species. Or possibly use resins, carbons and binders to try and mask the excesses of an impossible situation.

Another solution: use regular water changes to bring the excess build up and declining mineral/buffer content back to base line optimal readings. This would be in the area of alkaline reserve, ORP, nitrogenous waste ( nitrate) , phosphate, bacteria count, algal balance , desirable gas saturation ratios.

Amounts and frequency of water change is as much an art as a science. And depending on circumstances, water changes can be a breeze or a real pain! Source water quality is definitely a case of great concern. Most serious hobbyists use some form of pre-filtration to insure that raw water is not too raw. Here is where resins, carbons and filters represent money well spent. Some hobbyists have taken it even a step further and use this entry point an opportunity to bring water to even a higher physiological compatibility with their koi by adjusting source water pH and hardness. Depending on your source water, you can devise a schedule and use testing for things like nitrate, phosphate, ORP, pH, bacteria count, BOD , etc., as guides to whether you are keeping up with the dynamics of the closed system.

Personally, I do two water changes a week, which is excessive for my particular system, but the koi really do grow and glow as a result. This is in addition to my routine of ‘sump dumping’ daily in summer and twice a week in winter. The amount I change is 15- 20 % in winter and as much as 25-30% in summer. I used to do more but found that, that much raw water ( C2O well water issues) was excessive and becoming more of an un-stabilizing force than a stablizing one.

In designing your own philosophy and approach to water changes, first consider your stocking level and then your feeding schedule and food type. If we wish for a true optimal BASE LINE reading on these various parameters, we must appreciate that the koi population’s basic metabolism will require a certain minimal maintenance and counter manning, and THEN the type and amounts of food added from season to season will require an additional safety margin. This becomes evident when you shift from say, wheat germ pellet to hi protein pellets- you can actually SEE the effect on water in a closed system very quickly . This is especially true if temperatures are not ‘right’ for food type and the bulk is passed through the fish semi digested.

I’m sure the advance keeper will agree with this statement- a water change is the single best alley one can employ for the month to month stability of a pond. Poor source water and excess water changes can certainly be an un-stabilizing force. But a closed system , left to it’s own dynamics, is the ultimate unraveling environment.

-JR

Posted by Bradley Bradley in reply to "Water changes"

"In designing your own philosophy and approach to water changes, first consider your stocking level and then your feeding schedule and food type."

JR, this is the bit I am learning, mostly via trial and error. I would also add that some of the approach should take into account what of koi you keep (as an extension to the idea of stocking level). I have focused my learning on differences between males and females and therefore I have set-up different pond types with close to identical environments.

1. Female Pond
2. Male Pond