Aquaponics - Nebuliser

We don't like zeds in this country.

That's why we spell words like "nubulizer" with an "s".

I pretty much spell how I think words should be spelt, and let Ubuntu take care of the rest.

But...

This bit is the bit of a medical nebuliser that seems to make the fog.

As far as I can tell (I unplugged the hose when nobody was looking) the rest of the device is just an air pump like the kind people use in their aquariums or aquaponics systems.

The medication is in liquid form, and sits above the aqua disk. That's aqua the colour, not aqua as in Aqua-Man.

From what I can work out, the liquid spills under the disk via the tiny grooves you can see in the side of it, and then runs into a stream of air that employs standard magic to make it into fog.

With me blowing through it, it creates a spray rather than a mist, and it's not even close to a fog.

That's it working in my hallway.

It wasn't as bad as it looks on camera.

So I'm guessing the pump can dump a lot more air pressure to it than I can.

That, or the medication isn't water based. But I don't think it is anything other that water, because an angry nurse once told me it was drug laced saline [solution].

Up close it looked like this.

Not very foggy.

Even as it is, it might make a useful aerator.

There are a lot of different thoughts out there as to how aerators work in a fish tank, and I wish someone with an oxygen probe would just do a few simple tests and prove what's going on.




Oxygen (and other gasses) are soluble in water. A lake gets it's oxygen from the bit that meets the air. That's all good and well for a lake, but people like to keep more fish per cubic metre than a lake, so we need to add air. The air only dissolves into the tiniest depth of the top before that bit gets saturated with as much oxygen as it feels like carrying, and leaves the rest to float around, way up in the sky.

Unfortunately there is a lot of poor science out there telling us how and why water and air does all this. Actually the science isn't all that poor, but tends to relate to sewage treatment rather than fish tanks. And then does some dodgy science as well, but I digress.

1. Some say the air bubbles from an air pump in a fish tank simply increase the surface area exposed to the air. The fish tank surface, plus the surface of each of the many bubbles equals lots of surface.  It definitely does that, and there is the added benefit that the air is under pressure. The deeper it is, the more pressure there is. It turns out air under pressure likes to squirm it's way into water a bit more than usual.

2. Some say oxygen uptake is mostly done as the bubbles hit the surface. Something about the large increase in surface area as the bubbles break and splash around all over the shop.

3. Still others think that all that other stuff is happening, but the main thing the bubbles do is drag water up with them as they rise, and as a result, create a current in the tank, and constantly expose new lump of water to the air.

4. Many combine any number of those and some add some stuff about breaking surface tension. Some quote other people saying stuff about breaking surface tension being important, and get that mixed up with number 2 above. Others think that breaking the surface tension just means you don't get a sheet of water that keeps being the topmost layer because surface tension looks a bit like it might be a separate bit of water doing the surface tension thing, and it might not be moving much.

5. By far, the majority of people don't care because they don't have a fish tank, and the most intelligent of us that do, tend to ignore the entire debate and just stick an air stone into our tanks and attach it to an air pump.

Sadly I don't belong in that last category.

I care.

I've cared since I was a lad.

I had some guppies once in a five foot fish tank.

They all got out and went for a walk on the carpet.

They took all the water with them.

But luckily, a nice farmer took them all to his pond where they lived forever as far as I know.

Anyway...

I tend toward argument 3 with perhaps a little 4, but definitely aiming for 5.

I have only two fish in 1000 litres of fish tank, so there isn't a lot of competition for air, but I also have worms living and reproducing all completely under water. Two of my grow beds are run as constant flood beds. This means that they are always full, yet my worms don't drown.

This is a good indication of well oxygenated water, because it turns out that worms only drown when the water they are in doesn't have high enough levels of dissolved oxygen. Most aquaponics systems end up full of worms, even if you don't add them. I added some adult worms to my system ages ago, and regularly find adult and baby worms when I pull up a plant.

I have no idea how much dissolved oxygen worms need to thrive, and I cant find the answer anywhere, so if you know a student that needs an experiment, make them do it.

But get them to tell me the results.






120 Things in 20 years, I'm not really sure what this aquaponics nebuliser post was really about in the end, but I for one feel more informed as a result of having read it to check it to make sure not too much of my head fell out.