Backyard Aquaponics
A place to discuss aquaponics

This might be nit picking but I am curious as to amount of water in a given meter of GB medium with different sized/density of media?

Are there any figures for say pea size gravel to lava rock? Also, I was early on exposed to Stephen Spottes books and value the porosity of different media for denitrifying bacteria.

Welcome, Yaacov.

I don't know of any research, and I suspect the differences would be fairly minimal unless talking of 3/4" blue metal or some large granite rocks... My system is a mix of stalite, lava rock (in the bottom) and some gravel...

Frankly, there is some debate about GB to FT volume, but the differences are so broad (1:1 or 2:1 and everything in between) that porosity will hardly make up the difference in the extremes...

My 2¢

CB

Hi CB

Thats why I wondered about nit picking, just a thought that occured while looking at FT and Sump and GB ratios.

Thanks.

Well the range for how much volume might be needed to flood a bed, most people go with roughly 40% as the average but one should figure 50% when estimating sump size needed. The smaller the media, the less water it will take to flood the bed. Of course as plants grow in the system, roots will take up space in the grow beds and affect the volume needed to flood and drain the bed.

As to the texture of the media and bacteria colonization. If you are aiming to have as little grow bed as possible and you will be removing solids before sending the water to the grow beds, then it might be worth going to extremes to get the most pours media possible. However, if you will be going with a 2:1 ratio of grow bed to fish tank, you can go with whatever appropriately sized media that won't affect pH and it will still be just fine.