Backyard Aquaponics
A place to discuss aquaponics

So, before quarantine, and shut down of the schools, wayyyy back in last August, i picked up a few day old catfish fry....like 300. About 100 perished on the way home. About 75 or so died over the next few days. But I was left with over 100. Boy, have they grown....

Anyhow, at least half (likely a little bit more) were destined for a bigger system (around 700 gallon ft) at a school.....which was well along the way, but couldn't be completed due to the Covid.....damn Covid. So, now, I have a lot of fish... In what was meant to be a temporary holding place.

Perfect excuse to expand my system....Some of them are still destined for the school system if things pick up again in August. Well, I hope, and anyways, now I'm here.

In the mean time, was considering doing some deep grow beds to increase biological surface area....and help with ammonia conversion...I could get double the biological surface area in the 4x8 space that I have available.

I'm trying to move fast, since the fish metabolism is on fire right now, and the ammonia has been creeping up...I know I am drastically over stocked. The water is salted, well aerated, and I have cut back on feed.

I've seen a few people mention deep grow beds here, and I have a few ideas/ questions.

1st:
I have a 4x8 space. I was thinking of making the grow bed with a 4x8 foot print, divided lengthwise for a set of 2x8 beds in the same space. These would be 2 feet deep.

I would do this size because of my liner's size, it is slightly over 6 feet wide. This would give me the maximum size in the allotted space.

2nd:
I just scored a ton of scoria!! I figured I could use the scoria at the bottom, since it has irregular edges, and should allow more water flow/ less crud build up.

3rd:
Aeration- I was thinking of having some slotted pipes that extend to the bottom of the grow bed, with an air stone popped in to avoid anaerobic zones. .

4th- I was thinking of having one half constant flood, and the other flood and drain, mostly to minimize drastic water level changes to the sump. But, also to compare growth in the different systems.
But, how would one go about draining such a deep bed?

Would a bell siphon work at this depth? It's what I've used up until now, and what I'm comfortable with. Any other methods that might work with the pump constantly running. I've thought about a flout.

I know I could sell some fish......and I have tried on craigslist and got no responses. It's kind of a weird time to sell things...

I decided to try it out. I guess I'll find out for myself!

I saw a post where some of this was discussed, but not in much detail. I was hoping to get someone's personal insight, and potential mistakes to avoid. And hopefully see pictures. I am a visual learner!

I understand that the plants will likely only use a foot's depth for their roots.
I understand that their might be a risk of anaerobic zones developing, but this can be resolved by adding air.

My purpose is to try to increase the surface area for bacteria to aid in ammonia processing, to keep a slightly higher fish load.

Someone said that they have used meter deep beds, and liked the results. Stuart, I believe, but it looks like he hasn't been active in a while.

I remember that someone used almost whole ibc's as grow beds, but I can't remember who, and I wanted to read that thread again, but can't find it. Does anyone recall this?