Koi Pond Basics: How to cycle a Koi Pond by Joshua Whipday of Satomi Nishikigoi
What happens when we introduce fish to an immature pond?
When we introduce fish to a pond (in too large numbers) with no nitrifying bacteria they excrete ammonia. There is nothing in there to deal with this ammonia. It builds and builds ultimately killing our livestock.
How does a pond cycle?
We put fish in a body of water. Fish breath, wee and poo in that body of water. This releases ammonia into the body of water. In a new pond with zero nitrifying bacteria colonised in the biological section of the filter and pond surfaces, this is the equivalent of us weeing and pooing on the floor of our homes and not moving it. Of course we would become ill. When nitrifying bacteria starts to colonise in the pond (on all surfaces ie, pond walls and filter media) this is the equivalent of us moving some waste to the toilet. The first strain of beneficial nitrifying bacteria to colonise is nitrosomonas. This strain of nitrifying bacteria consumes Ammonia. When Ammonia is consumed by nitrosomonas, the by-product is Nitrite. When Nitrite is consumed by the second type of nitrifying bacteria called Nitrobacter the by-product of this is Nitrate which is much less toxic to fish. We class this as a ‘cycled pond’ meaning safe for fish. But first let’s cover managing Ammonia in the pond.
Managing Ammonia in a pond
If we can understand ammonia we can cycle our pond much easier resulting in less stress to our fish and ultimately less dead koi!
As ammonia rises so does the food source for nitrosomonas. Nitrifying bacteria colonise in numbers relevant to food source and available surface area (the more food source ie, ammonia & surface area ie, filter media the larger the colony of nitrifying bacteria. However if we don’t control ammonia with water changes it can get too much for our koi killing them, so this is a fine line. A slow steady trickle of fresh (de-chlorinated) water can be very helpful to ensure we have some ammonia (to allow nitrosomonas to colonise) but keep our fish alive in the early stages of the nitrogen cycle. I have to mention PH here as it plays a huge part in ammonia toxicity.
How Ammonia & PH Interact
An easy way to explain this is the higher your PH is the more toxic Ammonia is. For this reason I like a low PH while ammonia is present.
I want this to be a straight forward guide so I won’t delve too deep. However there is helpful tables all over google which explain the correlation between ammonia, PH & Temperature very well if you would like to learn more.
Conclusion to managing Ammonia
Ok we have Koi in our new pond and ammonia is present. IN MY EXPERIENCE if we use the factors below our koi will be ok.
- Maintain a low PH
- Maintain 0.3% salinity with PDV salt (do not use table salt this contains iodine)
- Have a store of fresh de-chlorinated water on hand (if possible, for emergencies)
- Trickle in
- Remember we do need some ammonia for bacteria to colonise but keep under 0.2ppm
- Remember you manage how much feed goes in more feed = more ammonia use this to your advantage
- Keep the same moderate amount of food & fish throughout the cycling process
Managing Nitrite in a pond
Ok ammonia has spiked and you have kept it from raising too high. A colony of nitrosomonas has now built up and started to consume ammonia which is great news. Ammonia has started to drop. Nitrite will now start to rise presenting a food source for nitrobacter. The ammonia and nitrite are now elevated however there is a curveball here. Nitrite is more toxic at a low PH, but hang on we’ve just utilised a low PH to help manage ammonia?
Remember in the conclusion to managing ammonia we added PDV Salt to our pond at 0.3%? This will help us detoxify nitrite. Adding Salt to our pond adds chloride ions into the water. These ions block nitrite molecules and stop them travelling into our koi. Maintaining a level of 0.3% with a salt meter will usually alleviate the effects of moderate to high levels of nitrite.
How much is too much Nitrite?
Again as with ammonia, for the pond to cycle we need some nitrite for nitrobacter to colonise. However nitrite levels over 0.15 milligrams per litre can be harmful to koi.
Failing to keep this under control can result in ‘brown blood disease’.
What is brown blood disease?
Again I want this blog to be simple yet helpful so I won’t delve too deep.
Brown blood disease is caused by elongated periods of high nitrite levels. Brown blood disease prevents oxygen successfully being transported into the blood essentially suffocating the koi regardless of oxygen levels within the pond.
Symptoms of high nitrite (although this should already be picked up on a test kit) include:
- Flashing / flicking against surfaces of the pond
- Laying on the bottom with fins clamped ie, pectoral fins kept close to the body “clamped” in
- Fish still may feed and raise up from the bottom but return back down after feeding
- Gasping for air - very near death
If your koi are showing these symptoms and your nitrite tests back up evident high nitrite a big water change is essential ensuring you maintain 0.3% salt levels.
Whats next?
As we go through the nitrogen cycle at this stage ammonia will now start to drop as nitrosomonas have colonised in big enough numbers to convert the current amount of ammonia entering the pond into nitrite. Consider this part one complete. Keep the amount of food going in the same amount daily, the salt at 0.3% and the nitrite under 0.15 milligrams per litre and your golden!!
Over the coming weeks a similar thing is going to happen, nitrite is going to start to drop and require less water change / trickle in & salt as nitrobacter colonises in larger and larger numbers.
Once ammonia and nitrite hit zero we consider this a cycled pond safe for fish. At this point we should allow a trickle in to slowly dilute the salt content as to not rely on salt. Nitrate will now build in the same way ammonia and nitrite did although there is a 3rd bacteria that will turn this into free ammonia or nitrogen gas which is released into the atmosphere when the surface water of our pond comes into contact with air. This being said from my experience this is very hard to achieve and diluting nitrate with water changes and trickle in is must easier.
Ok, for easy maths lets say you cycled your pond with 5 fish and 50 grams of food daily. You used this amount all the way through essentially meaning your filter / pond is cycled to this amount of waste ie, ammonia & nitrite. Going forward everything should be slowly done, what I mean by this is when we increase the amount of food we increase in 10g increments not 100g and of course when we introduce new fish we introduce 1 or 2 of appropriate size not 10. A bit of common sense really. Slower increments are always better for an eco-system, it allows it time to adapt.
Conclusion
This is my first blog and I really hope it isn’t too long winded and helps you! There is many more I will be doing in good time.
This hobby can feel complicated but with a little effort into research such as this blog, it can be fairly straightforward. Of course there will always be problems and hiccups along the way even the most experienced have them but thats all part of the fun!
If there are any problems your facing or would like me to cover in a blog do not hesitate to reach out and email me josh@satominishikigoi.com my aim is to make Satomi Nishikigoi educational as well as a place for great koi and all the essentials. I am always happy to help.
Written by Joshua Whipday - Satomi Nishikigoi Founder
www.SatomiNishikigoi.com
DISCLAIMER: ALL COMMENTS ARE MY OWN - FOLLOW AT YOUR OWN RISK.
