Surface v.s. Bottom Aeration

Recently I've been doing quite a bit of research on aquaponics and Ive been hearing a lot of different views on subject of aeration.

Here's just two examples I've come across

"Bottom up Aeration systems are 5-10 times more effective than surface aeration. " ~http://www.naturespondcare.com/education/bottom-up-aeration-vs.-surface-aeration.html

"More often than not, low dissolved oxygen levels are the result of inadequate surface aeration. It's easy to forget that the gas exchange only occurs at the surface, and only in the area affected by the aeration technique."~ https://lakewaytilapia.com/How_To_Raise_Tilapia.php

Soo I want to hear from the pro's what are your thoughts? any experience in this field.

 

I am certainly not a pro but here are my thoughts:

you want your bubbles as fine as possible to obtain the maximum surface area to water ratio.
The amount of oxygen dissolved in the water is dependent of the pressure of the system as well as the temperature of the water. Higher pressure lower temps = more oxygen dissolved.
I agree that gaseous exchange occurs at surface of water but also occurs more rapidly with agitation.

 

If your concern is aeration, then surface agitation is the first thing you must worry about. Whether you achieve this with bubbles or filter flow is irrelevant. Gas exchange at the bubble surface (big or small) is insignificant at the level that it happens, especially compared to the kind of gas exchange you get with surface agitation.

"Bottom up aeration" - ultimately this will agitate the surface, but besides this the only other benefit would be circulation of the water, namely bringing up the potentially less-oxygenated water from the bottom toward the surface, where gas exchange can take place.