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Bioball question......


ViS

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Ok forgive me if this is a dumb question laugh.gif

How efficient would bioballs be if they had bubbles coming up through them from underneath?

I'm going to run a couple of 25cm sq. bioball towers into a 4x2 sump tank, but then the excess surface area is wasted (I'm not going to use a drip plate or spinner arm as the sump will be quite full and no height for drips).

I have a heap of excess air from my large air pump and I was considering the possibility of using half a dozen of those flexible air curtains along the bottom of the sump with a couple of layers of bioballs covering the surface. There would be lots of small bubbles travelling up through the bioballs constantly. Would bacteria colonise on the bioballs well enough to make it worth doing?

The top layer would remain wet due to the popping of the bubbles and the layer underneath would get constant water flow and air passing close enough to the bioballs to provide them with oxygen surely?

dntknw.gif

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I'm sure it'd work, how well is the question I guess.

maybe uplift tubes with airstones in them to pull the water up over the bioballs higher than just air stones/curtians?

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If I did that, I'd need about 50 uplift tubes to cover the spare surface area.....

The towers only take up two square feet out of the eight, so I'm left with a whole lot of empty surface area.

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Andy -

I dont think there is any exact answer for this - but I guess these points are all valid.

1. Bioballs work underwater (ie: bacteria still colonise the balls and reduce ammonium to nitrate).

2. Bioballs work more efficiently in a wet and dry system (as there is more O2 available to the bacteria and presumably you get a greater abundance (and possibily different species) of bacteria) than in situations when the balls are submerged.

3. Air bubbles in tanks dont actually contribute much via O2 solubilisation because their "residence" time in the water is brief. In saying that they:

a) increase water movement, so more water gets exposed to the water:air interface

b) break up oily films (which limit O2 diffusion).

4. Given all these factors, and the relatively fast flow of water through sumps, I'd be guessing when I say that I doubt there is any real benefit to be gained.... BUT if you've got spare air and it's low on the hassleage (and expense) - then it might be worth a go.

Dave.

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if the media is going to be constantly submerged why not use a media with a big surface area, something that was made to be submerged? like eheim ehfisubstrat, matrix, micromec, etc etc.?

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Momo -

Bioballs work just fine underwater. Yes, other products have larger surface area... but MORE's law doesnt always need apply.

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I guess using the bioballs with bubbles flowing between them constantly should at least move a lot of water past the colonising bacteria, enabling it to work more efficiently?

I'll probably give it a go. It's not going to be worse off anyway. wink2.gif

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If you can get a notice a difference (tank perameter wise) with the air on or off you're more observant than an observation machine I guess.

you can't just plumb in the return line with a few t pieces to spread it over the top - rather than a spinner or a drip plate?

I made spray bars with 10mm holes for all my wet/drys. just that black irrigation poly stuff & low pressure barb fittings

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I could drip it over the top, but there's no height which is the problem. The bioballs would still be under the surface, an inch or two below the top, which makes dripping water on top pointless.

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In my opinion, bio balls are best left in out of water (wet and dry) situations. Underwater they will have just as much surface are as they will out of it, but the difference being they have less surface area than most other biological medias, so they are a poor choice for submersion. They come into their own once water is trickling through them, but under water they are a poor choice.

Submerged, their limiting factor will be surface area when compared to other media available. Using bioballs submersed you are organising a limiting factor which is opposite to best practice.

I happen to think that putting aeration under them will help. As Dave said an air bubble doesn’t spend much time underwater, but I think you need to take into consideration that each bubble has a fairly large surface area, and the are thousands and thousands being produced on a on-going permanent (blackout excluded) basis, so they will be vastly increasing your tank’s surface area footprint – which has to increase the available O2, which is decreasing one of the three limiting factors for bacterial population life- surface area, O2 availability, and food (fish waste).

However, as mentioned with the limiting factor of a “chosen” smaller surface area by using bioballs underwater, it may be pretty much a muchness.

Craig

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Thanks Craig.

I'd like to remind everyone that the floating bioballs are simply extra on top of the actual drip filter. I'll have the bioball towers in the sump, but will add the extra floating ones as a bonus.

I'll give it a go. If all the fish die, I'll let you know laugh.gif

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