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Pond not getting enough air

25 9:51:27


I've just had two fish in my pond die and I assume its due to lack of oxygen in the water.
Pond Facts
Size 9m x 4m x 1.8m (possibly deeper at one end (I cant remember)
volume approx 60,000L  13,226 gallons
Number of Fish, unknown probably 60 although that is a massive guess.
There is no filter.
Currently using a Blagon koi air 65 air pump with 4 lines attached (65l/min)
There are a large number of Plants in the pond, i'll try to attach images.
The pond is in the sun and the air temp is about 20oC

There are no obvious markings on the fish.
We have had the pond for a number of years, it has never been filtered before and we haven't had any problems with the fish dying before. There have been no recent changes to the number of fish, however the weather has just started warming up.
I was wondering if there was a way of calculating how much air a pond of this size should get.

Many Thanks

Dear James,

Thank you for your e-mail.
Unfortunately the answer is not that easy.
It can be a lack of oxygen, however not necessary.
Do you have a pump for circulating the water also?
If oxygen is the problem, then you would have noticed that fish are swimming at the surface.
Did you notice fish behavior as strange? Like jumping, hanging on the bottom, flashing or rubbing?
This indicates parasites or poor waterquality.
Is the water very green from algae, than it could be lack of oxygen as alga can use lot's of oxygen.

Also remember that oxygen pumps will reduce on its production due to age, depth and length of placing the oxygen outlets.

Personally first thing I would do is check behavior of the fish.
If they are not hanging on the surface at evening or mornings I would try to test the water and if fish are jumping are anything like it, I tend to take scrapes for microscope study to check for parasites.

If nothing seems to be wrong, you do no harm in adding an extra pump.

good luck and happy pondkeeping!
Kind regards,