I spent many years in the pet/aquarium trade and the one thing that tends to confuse new aquarium/pond keepers the most is the nitrogen cycle. I’ve explained the simplified version of it to hundreds of folks over the years, and it usually resulted in a tilted head response, and then frustration when I wouldn’t sell them the 50 new fish they wanted for their brand new 10 gallon tank.
Many people seem to confuse the term “cycling” as meaning that water is moving though their pumps and filters. So after a week or two of perfect water test results, they think the “cycle” is complete and they want to load up with fish. Uh, no.
So I thought I would share the water testing results I’ve logged on our new pond, just so that some of the new hobbyists scanning the forums for info can get a general idea of just how long it can really take for a new pond to “cycle”. Obviously, NO POND IS EVER THE SAME - as so many factors play into how fast or slow it may be for bacteria to colonize and for the nitrogen cycle to “complete”. Temperature, pH, ammonia load…and the list goes on - and gets deeply scientific. But this post isn’t meant to open up a biology book of information to muddle brains, or feed debates or egos. I am merely posting my results, in a simplified manner; to drive home the point, that the nitrogen cycle takes time. And that patience and care are required when stocking a newly filled pond.
Background:
Our pond: 2,000 gallons
Location: Mostly shade in a mountain woodland – 8-12 degrees cooler than valley floor in Summer.
Filtration: One 17” filter falls unit with pads and bio-media with outflow over several stones into a deeply graveled spillway which then flows over a stone slab before re-entering the pond. No skimmer. The pump moves the water through this system at a rate of approx. 1 time per hour (and that’s the way I want it).
Other aeration/water movement: Filter-less side waterfall pumping at around 1,700 gph. No area of this round-ish pond is left stagnant.
Plantings: Began being added at day 3 and continues
Fish stock: Two goldfish added at 2 weeks. One additional fish at 23 days. One additional fish at 33 days. One additional fish (moved from our other pond) at 44 days, one more at day 45, and our last four small fish from the other pond transferred on day 48. Total of 10 small goldfish to 2,000 gallons.
Results:
Testing began at day 19 after filling pond using an API liquid freshwater test kit. Ammonia, Nitrite and Nitrate all testing 0 ppm.
· Water temperature – average of 72 degrees over entire testing period
· pH – Consistently 7.4
· Ammonia shows up at .25 ppm @ exactly 3 weeks
· Three days later the ammonia rises to .50 ppm, and STAYS there up until week 10. No water changes, no freaking out, no stress to fish.
· At 66 days nitrite finally appears @ .25 ppm, ammonia still at .50 ppm. No freaking out, fish still happy, just added Pond Prime to help detoxify nitrite.
· At 68 days Nitrate testing just barely begins to show color
· At TEN WEEKS Ammonia finally drops to .25 ppm, nitrite still shows .25 ppm, and Nitrate shows @ 5.0.
· At day 72 – Ammonia – O, Nitrite – 0, Nitrate – 0 – All fish healthy, no fish lost, no extra gray hairs.
Testing will continue, as it is possible for things to fluctuate. But there it is, ONE example of how long it can take to start seeing results in the nitrogen cycle.