Air, Oxygen and BOD.....

[GreenDiscus]

The supply of Air, or rather the 16% Oxygen within it, is as vital for our fish as it is for humans, but do we as Discus Fanciers give it enough credit ?? In addition, how much of this Oxygen is transferred through the bubble surface and actually into the water. It could be argued that perhaps only 10% of the available oxygen in the Air is dissolved into the water.

Yes, that would mean a mere 1.6% of Oxygen as a percentage of the total volume of Air introduced into the tank !!!

There is another organism apart from Discus in the tank that requires a good level of Oxygen and that is our “Beneficial Bacteria”, on which our eco-system depends. These organisms need good levels of Oxygen to help them devour the Nitrates and Nitrites etc. BOD (Biological Oxygen Displacement) is the measure of the waters capacity to hold oxygen that is greatly reduced by the introduction of Biological pollutants from our fish.

Enter - that pathetic piece of aquarium equipment the Diaphragm Pump !! You have probably all got a drawer full of dead examples of this piece of equipment, but even working correctly, is woefully inadequate at providing enough Oxygen.

Discus and the BOD reducing Bacteria need high levels of dissolved Oxygen, and in my view it affects everything to do with the fishes health. This includes the bright eyes, colour, feeding, breeding and also disease resistance. There is evidence to suggest we may be able to reduce water changes and/or increase stocking densities !!

So what do I use – my 450L display tank has a 1500L/Hr external filter AND a 2000L/Hr internal filter with a Venturi Air inlet pipe set for maximum air. The 150L tank has a 400L/Hr external filter AND a 800L/Hr Venturi connected Internal Filter. The photo attached also shows that the Venturi Air is focused in the direction of the External Filter Inlet in order to increase Oxygen supply through it.

I would be very interested in the Forums view………..!!!

[samir]

i wouldn't use the internal filter at all. if you want air put an airstone.

[dreamer]

wait until all those air bubbles get into your canister ....

[GreenDiscus]

Thanks Guys
The Second filter is a bonus - being sponge vs noodles, carbon etc it can be left running on its own for a week in case of medication that would otherwise be removed with carbon. However, its is a very long time since I used any medication which is my point.....
In over 12 months the external filter has not "run dry" with bubbles. Its the BOD reduction that is vital and that needs the oxygen. I used to have a trickle filter system in the lid that was open to lots of oxygen and that was also good - until on holiday it blocked and sent the ceiling below crashing down under 150litres of water !!

[FishLover]

Hmmm, I was looking at the trickle system set up and the fist thing came to my mind was what would happen if it blocked? I think you just answered my question.

Thanks. I will stay with the cannister system.

[samir]

i'd remove the internal filter, discus dont like to jet ski. all i use are air pumps with sponges. that works for me.

[GreenDiscus]

Yes Fishlover the building works to fix the loss of the ceiling below was no joke, so I would avoid the trickle systems in the tank lid. Fantastic for Oxygenation and BOD reduction - I almost installed a trickle system under the tank that had a slowly rotating bar (like in a dishwasher) dropping water onto noodles etc which looked excellent.
Hey Samir - I currently have 50 discus in the tank. and they love Jetsking !!!! The highly oxgygenated seven water changes per hour (less with the Venturi) is needed, and the picture was less than 1/3 of the tank length anyway.
In the wild, oxygenating rapids will empty into the slower pools.....

[samir]

:? mine dont seem to like any kind of current at all and there's nobody who could ever convince me that they do. more air however does induce them to spawn. how about some full tank pics, looks like a nice setup you got there. :)