Backyard Aquaponics
A place to discuss aquaponics

So I'm starting up a new system and am a bit confused about the grow bed media size. I'm going to be using lava rock but my local dealer offers it in 3-5mm, 5-10mm and 10-20mm sizes. I figure 3-5mm would be optimal because of the larger surface area available, but is there any advantage to using larger sizes? Also, anyone have any idea on how to rinse it of dust quickly?

Maybe use the larger size. you would ideally want the media to stay in your grow bed. Sub 3mm holes in your media guard may/will be problematic.

Rinsing, no easy way. Hard work. I used a bucket with holes in the base and dipped multiple times in a larger tub. Plenty of examples of more sophisticated set ups if you use the search

I would go with the medium size. I have gravel about that size that works fine. Smaller I think would be a problem as mentioned. The bigger size may not provide the right space for the plants to take up the bacteria. And the medium size should give you surface area like you said about the small stuff. Just an idea...