Quote Originally Posted by davidstcldfl
Quote Originally Posted by Shas
David, what's the idea behind using such large media?
I see 1/2 -to- 3/4-inch river gravel (river rock!)
recommended everywhere I look,
but I'm darned if I can figure out the reasoning behind it.
Keith and Alex already said it.....the smaller stuff clogs quicker then the large stuff.
Shas, if your stocking density were on the light side, or if you had more media beds then the 'given' ratio recommends.... your 'pea gravel' should work

Here's what I experianced...
I was given some river rock. It was on the small size...around a half inch. I used it in some small media beds.

When I revamped my system, I moved the original media beds and rocks.... I rinsed them clean (with system water) before setting up the beds again.
I added a few more media beds and I used the larger river rock...about 3/4 of an inch.

The beds with the larger media seemed to take 'a lot' longer, for them to be as productive as the beds with the older/smaller media.
I have a few thoughts on this...

One, did the fact, that the older/smaller media, already having bacteria growing on it, make the difference ?

Two, the media beds were fed by a common header, with each bed having a tee, with a reducing branch with a ball valve.
The beds with the larger/newer media were the 1st ones to recieve the fish water....the older/smaller ones were the last to recieve. I wonder if 'more' fish waste passed by the 1st few sets of tees, and the last few beds recieved more fish solids ?

Three, the smaller media obviously collected more solids, so I would think those beds had more nutes available for the plants. (?) (all the beds had red wigglers)

Maybe it was a combo of all of the above....?
id say its the bacteria already on the smaller rock that made the most difference. Also the more fish waste being broken down by the worms might have helped a tad more to.