This question was asked on another forum, i thought that i would ask the question here as well.

Traditionally we know that one should have a 1000 Liters of pond water for every 66cm of fish. But this only takes into considuration water volume and not the amount of filtration.

So lets say that we have two ponds, identical in shape and in amount water circulating per hour:
(A) 10 000L pond with a 25L Ultra Zap Bio Filter
(B) 10 000L pond with Nexus with 300L Kadlness.

Lets also assume that the ponds in the example above are running in utopia where the power never goes down and the pumps never pack up.

How would one calculate the stocking levels? Would one only work with the water volume and ignore the filtration or is there a way of including the filtration in this calculation aswell.

The 66 cm rule has been developed quite a long time ago when the filtrations systems were not as hight tech as today, and is based on an average filtration system.

Obviously one should take into consideration the effectiveness of the filter, but it should not be over emphasised.

One can not answer the question without looking at the possibility of power cuts, because should a power cut occurs, the fact that the filtration system is a nexus/kaldness is irrelevant.

Yes, you should have a power backup, but what if the power backup does not work, you are not home to put the backup on, you ran out of petrol, your generator does not want to start, power fails when you are on holiday and you don't know about the failure for a couple of hours etc.

Your filtration system will soon become toxic, your pond will soon run out of oxygen if you went beyond the 66 cm rule, and the Nitrites and Ammonia will build up. Yes, you will not feed during power failures, but Nitrites and Ammonia will still be produced from food intake prior to the failure.

You can argue that dealers have large stocking rates, but they have proper backup systems which the average hobbyist wont have. We have generators and Battery backups, and there is always people around to monitor the state of the ponds, 24/7.

At the end of the day, it is all about the risk you are prepared to take. If your increase your stocking rate above the 66 cm rule, you are running risks.

It does happen from time to time that you have to medicate seriously, or you might have to empty your pond to do repairs, in which case you might loose your beneficial bacteria. The Nexus or kaldness will not save you in such event.

In the beginning of spring, the water temperature will increase and so will Nitrites and Ammonia at a time when your nexus or other fancy system have not kicked in properly. If you went beyond the 66 cm rule, you might suffer losses, despite high tech filtration.

My advice is, don't rely too much on high tech filtration. Obviously you can increase a bit, don't rely too much on it.

I also believe that growth rate is dependant on volume of water per fish. Dealers might have stocking densities far beyond the 66 cm rule, and despite the fact they they do not have Nitrites or Ammonia in their ponds due to high tech filters, they have a low growth rates.

It is a fact, the lower your stocking density, the faster they grow. Why limit your growth rate by trying to accommodate as many fish as possible? Rather stick to the 66 cm rule and buy only top quality Japanese fish than filling your pond beyond the limit with low grade Koi.

I agree with the statement Paul made.

Interesting thread and question – stocking densities and water volume.

You can have very heavy stocking densities in a koi pond. But there are major factors you will always have to keep in mind with high stocking densities. High stocking densities are similar to fiddling with water quality parameters. If you are going to do it then you have to keep a very close watch each and every day.

Firstly - oxygen levels. Oxygen levels are directly related to turn over rates for a simple reason - the only way oxygen can be dissolved into water is via contact with the atmosphere. The faster the turnover rates the more water will come into contact with the atmosphere. Oxygen levels will go up.

Counter balanced to this is the fact that koi are very efficient at removing oxygen from the water – via their gills. High stocking densities are possible so long as the pumps are pumping – at a fast rate.
High stocking densities are a problem when the pumps stop. Depending on the number and size of the koi they can suffocate if the pump is off for too long. Long before the ammonia or anything else becomes toxic, ponds with high stocking densities will suffer from a lack of oxygen. You can observe the effects of low oxygen levels on koi. You will see them “piping” at the surface.

The next big problem with high stocking densities is the effect pheromones have on other fish. Fish excrete pheromones in ponds. These pheromones will affect the growth and health of other fish in the system. The larger the stocking densities the more of a problem this will be. It will manifest its self, in the short term, as weaker fish being more susceptible to disease. In the longer term the growth of certain individuals in the system may be affected.

The average koi keeper can overcome the pheromone levels with water changes. As a matter of fact I believe that water changes are an essential component of growth in koi. Frequent water changes will make a difference.

Stocking densities will change with time – even if you do not add more fish. Every time a koi doubles in length it has 8 times the body mass. This in turn means 8 x more oxygen consumed – 8 x more impurities excreted into the pond.

When observing a koi collection the same thing crops up time and time again. Koi collections look better are offer more pleasure to the eye if there are fewer good quality koi than if there are more poor quality koi.
So your collection has to be dynamic. You purchase koi, enjoy then growing for a few years then move the poor quality ones on. Keep the better quality ones as this has tremendous rewards for your enjoyment as a hobbyist.

Regards,
Chris

Well Said Chris "as always".

I believe another aspect to consider is the amount of natural food(algae and other live food) with the associated vitamins/protein/minerals available.

The more fish in the same pond, the lessor the amount of natural food per fish.

I have two porta pools, exactly the same size, same amount of daily water changes, same filtration systems, same exposure to sun, same water source, no Nitrites and Ammonia in both.



In December 2007 I have placed approximately 50 babies(the best ones) in one and approximately 100 in the other one.

Today, after five months, the 50 are more than twice as big as the 100.

Paul have i mentioned to you that you have to much space on your property.

Thanks for the info, intresting experiment.

Now thats very interesting.

As unscientific as this experiment is, it simply blows any arguments about stocking densities out of the water. Don't over stock.

Question : are the two ponds filtration systems or water supply interconnected in any way at all?

I have an article that connects up with this. Will post it soon.

Chris

They are not interconnected at all.