Frequent Partial Water Changes

by Bob Fenner, www.wetwebmedia.com

There was a bit of discussion at January’s meeting of Grant Fujita’s California Koi Seminar regarding water changes; since there are no articles in the hard newsletter, herewith...The solution to the pollution is dilution
 
Probably the most important aspect of maintenance a pond keeper can do to optimize water quality and health of their charges is to change some of the water on a regular basis. This piece deals with the reasons for, and some rules of thumb as to how often, how much and how to make these changes.

Rationale:
There are several major benefits of frequent partial water changes: Dilution of nutrients, removal of particulate matter, removal of toxic, stagnant material, reduction of thermo- and chemoclines. Results anticipated are faster, more vigorous growth, reduced algae growth and odor.

It has been written in many fisheries, limnological (the freshwater equivalent of oceanography) and pet-fish hobbyist texts that along with temperature and photoperiod, metabolite ("wastes") build-up is one of the three most important factors influencing the health, growth and reproduction of fishes. More specifically; in the ornamental aquatic life trade, ammonia and other nitrogenous wastes are recognized as the number one killer of life in captive conditions.

Not to say that all the chemical "stuff" fishes and ponds cycle is toxic. Some metabolites, like pheromones, are actually known to have calming effects. Therefore the concept of partial, not total water changes. In doing these water changes we are interested in a dilution-solution; that is, keeping these so-called waste products at tolerable levels.

There are several ways this is accomplished. Most common are some forms of chemical filtration like carbon and ion-exchange materials. These are useful but often labor and money intensive in large pond-size volumes. Moreover, these chemical filtrants do remove desirable chemicals as well.

As stated in previous areas, it is vital that as much extraneous materials: leaves, dirt, landscape and rain run-off, etc. be kept from getting in the system. What little does make its way in should be removed by netting, diluted or removed by making partial water changes.

Some potential pollution will probably be added to your water in the way of food and fertilizer. Even without over- or mis-feeding and/or fertilizing, water evaporation has a decided negative chemical effect on an aquatic system. This "Dead Sea Effect" occurs as water evaporates leaving behind its' solid chemical constituents.
In building a water effect, planning must be directed at providing a source of water, and allowances made for occasional or continual dilution of nutrients and freshening by making frequent partial changes. So enough of the reasoning for making water changes; onto the nuts and bolts of doing them:

How often:
Depending on your pump/filter/circulation system, stocking and feeding regimen et al., partial water changes about once a week during the warmer months to about once a month during the colder ones, to none at all below 50 F (10 C) are about right. More frequent smaller amounts are better than infrequent mega-changes for substantive reasons.

How much:
Five to ten percent for larger systems and twice that for smaller (a few hundred gallons) is generally sufficient. The chemical/physical/biological shock from changing too much too soon is to be avoided.

By and large, water treatment chemicals for chlorine or chloramine are unwarranted with such frequent small percentage change; slowly refilling into the filter is recommended.

Make a schedule/notebook for your system and keep track of what you do and how it works for you. Patterns will emerge and give you a guideline for how frequent, how much you should change water.

How to:
However it is achieved, the part of the water and what's dissolved and suspended in it you want to get rid of is on the bottom. Overfilling, draining your system at the surface will not get you the results you are looking for.
In the happiest of circumstances you have a sump area with a slope over the surface of the basin leading to it. You open a valve or drop in a submersible pump and voila! the "bad" water and solids are whisked away.
In the second best scenario you have a skimmer system you can hook a vacuum-line to and suck out the bottom material. Less desirable routines involve a "skid-unit" with a gas or electric powered pump or a change in elevation to siphon off wastes from the bottom.

Conclusion:
Regardless of how well a system is designed and constructed, there will always be maintenance. Frequent partial water changes are one of the best ways of ensuring continuing success Whatever way it is done, change some of your water on a regular basis.

 

This site was last updated on February 11, 2002