I received a call yesterday from the owner of an Aquadyne 2.2 with Dynamax. He reported that he is now backwashing his filter every three days and algae appears to be winning the war for pond clarity.  When asked what he thinks might have caused this, he said that he has had good performance over the three years that his system has been installed, nothing has changed, but conditions have become progressively worse over the past year and he has no real clue as to the cause.

Further discussion revealed that when he bought his filter, he had forty small koi, but unknown to him his pond volume was already marginally in excess of the maximum capacity of his new filter.  His filter is rated at 4,000 gallons and he has over 5,000 gallons in pond volume.  At that time he had a youthful fish population, but large amounts of decaying fish excrement and habitual overfeeding had not yet become issues.  His pond was always clear and did not need frequent backwashing.

Three years of fish growth (with virtually no losses through attrition) has now brought his fish population to a point where his ammonia and other waste levels are beginning to far exceed the reasonable capabilities of any midsize filter.  Similarly,  the UV that has always served him well in previous years can no longer begin to keep up with the growing algae bloom.

Nobody likes to cull out and give away their ‘wet pets’ but if  they are left to grow and multiply beyond our capabilities to nurture them,  the whole dynamic of our pond environment can, and will, change.

Professional breeders are constantly culling out the more common fish and keeping the better-marked specimens for sale, and future breeding.  As residential koi keepers, we are not as aware of growth, and we are naturally reluctant to weed out and dipose of our excess populations, but if we fail to do so, Mother Nature will relieve us of the choice, and do it for us.

The koi keeper mentioned in this blog realizes that he must make one of two choices here;  one, cull out and give away some of his more common fish, thus bringing his fish population back to more manageable levels;  or two, upgrade his filtration system to the size he should have originally chosen, and continue to support his current population.  He is now considering marketing his Aquadyne 2.2 on Ebay to facilitate his upgrade to a 4.4.  Any takers?

Don’t be afraid to ‘inventory’ your pond annually, while you still have choices.