Backyard Aquaponics
A place to discuss aquaponics

Grow bed design issues, and traps for young players.

Last year I had a problem with a grow bed (GB) overflowing. I had to reduce flow to it, and then bump up the flow elsewhere to maintain the required level in the sump. Then another GB developed the same symptoms. And then another!

Eventually I ran out of adjustment across my five GBs and had no choice but to try to remedy the situation with more drastic action. I removed a very large volume of media from the first GB in order to clean out the media guard and to hopefully rectify the problem. What I found was that many of the holes in the media guard were blocked, but it was apparent that what I mostly needed was just many more holes!

The image was taken after I modified the media guard and returned it to the GB. The black holes are the original holes and the clean holes are the freshly drilled additions. I counted 72 original holes in the piece of pipe. It seems that when I first created this media guard as a novice, despite having read widely across this forum, that number of holes looked to me to be enough. Clearly it wasn't, as evidenced by the consequent overflowing of the GB in only its second season of operation. That media guard now has 350 holes.




I have now similarly retrodrilled hundreds of additional holes in the media guards of the two other second year (now third year) GBs. Within a few months, the other two GBs of more recent vintage similarly started exhibiting signs of blockage. I bit the bullet and spent the many hours required on each to shovel out the media in order to effect a repair.

Note that some of the hole blockages were greatly contributed to by the roots of certain plants, a couple of which were new to me. These included Chinese Water Spinach (or Kang Kong) and bloody feral cherry tomatoes (no, that isn't a variety name)!

If in doubt, drill, and drill, and then drill some more.

Nice one.

I think that my next incarnation if media guard might be large vertical slots cut into pvc pipe, then wrapped in stainless steel wire, well point style. Just typing outloud...

Your theory could have something to do with the variation in growth rates however I feel it has to do with the variation in the sizes of the fish when you purchased them. The first 2 years you got your fish from Ferguson Springs so the fish you started with would have all been of a fairly consistent size as I grade all the fish prior to sale, other places dont seem to do this. The end result is that I end up with all the runts which I grow out and then harvest in late spring at the modest size of around 300gms!!

Troutman, is it any wonder that I went elsewhere for my trout fingerlings after the first two seasons with your fish? Here's what you said to RupertofOz back in 2013:

C'mon Rupe, dont you keep the biggest and best ones for yourself like I do.
I always sell all my runts to PLJ, though of course he is none the wiser to this.

Eventually, I did finally wise up.

You are correct in that a change of supplier between years 2 and 3 introduces an additional variable into the equation. Having said that, the fingerlings I was supplied that year appeared to be a very decent and uniform size.

This is a good idea, Ron. I've incorporated slots into an outflow pick-up pipe elsewhere in my system, and it works just they way I want it to with no hint of problems, but I simply didn't think of using them in the media guard.

I like to think of myself as a lateral thinker but sometimes the blinkers are firmly in place, forcing a stymieing view.

Further to my Grow Bed ... traps for young players, I add this. Everything I read said that worms would spontaneously materialise in a grow bed, ie build it and they will come! This may be true in a lot of situations but clearly not in mine.

After no sign of worms after six months of operation, I introduced a dozen or so into each of my first three GBs. I have to assume that they perished because they were not sighted again. I added more after another six months, again thinking that 10-12 of the little hermaphrodites would be enough to kick things off.

It was only after my GBs started clogging up that I realised that I had no worms working at breaking down the root matter which was contributing to the media guard blockages.

The third time I introduced worms, and lots of them, they finally created a self sustaining colony. It was too late for the GBs though, and I had to dig out the media and worms to effect the media guard repair detailed above.

My system is currently humming. I'm stunned at the lack of solids in my biofilter drums and the constant high rate of flow being maintained through both sump pumps.

I attribute these improvements in my system's general state of affairs to:

1. the ease with which water presently drains through all five GBs due to my new 'holier than thou' media guards,
2. the lack of other fish species cohabiting with the trout,
3. the replacement of much of my shadecloth biofilter material with actual bio-media things,
4. my hard working worms.

"actual bio-media things" Can we be more specific please?

"actual bio-media things" is the technical name....

I refrained from referring to the media things as balls because they aren't spherical. I will post an image of one, soon.

That's them!

The media thing is called a "pall ring" in the petro chemical industry. They are available in many sizes from 1/2 inch to greater than 3 inches in diameter.

always a pleasure to read your trials and tribulations

Hi
here is the data on the media http://www.pallrings.co.uk/

cheers

PLJ, what size are your biofilter drums? They must bigger than most to keep up with the size of your fish tank