[Andros]

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So you have a venturi and three thousand water falls cascading several hundred metres into your Koi pond that is 600mm deep with 1000 square meters of surface area.

You must have saturated oxygen levels right?

Wrong!

Getting water to dissolve oxygen is hard and difficult. In fact it is a lot of work. We've been saying it for years - your Koi pond can never have too much dissolved oxygen in it.

The Japanese know and understand this. They have been keeping Koi for centuries. And in every single Japanese Koi pond we have seen there is massive amounts of aeration.

Venturis do NOT oxygenate Koi ponds. Waterfalls help, but should not be relied upon for oxygenation purposes.

πηγη: happy koi

Oxygen diffuses into your Koi pond at the surface, where it slowly dissolves across the air/water interface. The operative word here is "slowly". The warmer the water the less oxygen it can carry and the longer it takes to dissolve - yet the more active the Koi are and the more oxygen they require!

The maximum level of dissolved oxygen that water can carry is only theoretical and can perhaps be achieved in a laboratory under controlled conditions. Anyone who tells you that their water in their Koi pond (that actually contains some Koi) is at oxygen saturation is talking utter rubbish plain and simple. Even if their test kit backs them up it serves to prove that the test kit isn't worth its weight in dog turds.

It is physically impossible to achieve oxygen saturation in a Koi pond. The absolute best that you can hope for is to get as close as possible and within 80% would be exceptionally good. Oxygen is used in many processes - all of which have varying demand and hence the strain on the supply of oxygen varies considerably throughout the course of day and night.

So, getting oxygen in via the water/air interface is the area we should be concentrating our efforts on. Water at the bottom of the pond is not going to get any oxygen unless it comes up into contact with the water/air interface.

It is precisely this action that our air pumps deliver. By creating a plume of bubbles at the bottom of the pond, water is pulled up along with the bubbles as they surface, bringing deep water to the surface of the pond. This is called vertical circulation and it is this action that improves dissolved oxygen levels in a pond.

By bringing oxygen poor water from the depths into the air/water interface zone oxygen is given a chance to dissolve into oxygen poor water (which is much easier for the oxygen to do than if the water already contains a fair amount of oxygen).

Compare this with a venturi that basically pushes all the surface water (which is likely to be oxygen rich anyway) around the top of the pond. This achieves the square root of nothing since the oxygen poor water lying underneath remains there -out of the elusive air/water interface zone.

A waterfall does the same thing. Some oxygen rich water hits the pond, but unless the water fall is very steep and amazingly high, this water is unlikely to penetrate to the depths where it is most needed! So you end up with the same problem.

And no, just keeping the surface water well oxygenated is not enough, unless your pond is only 200mm deep... This is because no matter how much oxygen the surface water contains, it will not be enough when all your Koi decide that they need it for whatever reason.

The reality is that the vast majority of ponds run under oxygen poor conditions. It's a very simple test to make. If there are air stones, or aerated bottom domes, or air curtains in a Koi pond it WILL be far, far better aerated and more oxygen rich than any other pond with waterfalls or venturis could ever hope for.

And that folks, is the bottom line. Air into your pond to create vertical circulation within the pond is a critical element to Koi pond success. Do not underestimate it!


πηγη: happy koi