Fanatic Aquaponic Grow Bed Build – Bed #1 Complete!

Now that the tank is finally in the ground, I can now move on to the grow bed building portion of the greenhouse.

As before I’m sticking with the reclaimed lumber I had from the shed tear-down. Expenses here included screws, pond liner, paint and a few drill bits (go through them like butter).

As with everything in this build, I’m making it up as I go along.. i.e. I have no set plans to work from, I’m just building as I go based on a rough sketch I did when this whole ball of wax got started 😉

Originally I had planned on making the bed size 8Lx4Wx1H, but revised that just a bit to 8Lx3Wx1H. This reasoning came when I decided to take a look at how much space such a grow bed would take within the greenhouse itself. At four feet in width, it became apparent that my reach across the entire width of the grow bed would become difficult as I would only have access to the bed from 3 sides versus 4 (since that side will butt up against the outer wall of the hoop house). This was confirmed when during mock-up the wife mentioned as much for herself.

So, now the final tally will be 24 sq ft per grow bed versus 32. I’ve also decided to go solely with grow beds versus a split between beds and an NFT raft setup. Mosquitoes are a big problem and I’d just as soon avoid that fiasco all together.

Next up will be painting the growbed to help it stand up to the elements and so that it looks a bit better aesthetically. I’ve got several more of these to build, but now that I’ve been able to get through the first, I now know what I need to put together from a parts list standpoint and can pre-cut everything before hand going forward to save time.

Once I’ve got the first beds painting completed I’ll then start working on initially placing them in the hoop house and getting it leveled, lined and plumbed (this is another little bit of build I’m looking forward to with the PVC.. as I’ve never done it before, it should make it very interesting) 😉

Some items of note that came up after a good discussion with a fellow AP’er.. the ratio of fish to grow bed capacity came up. Now what’s considered a safe ratio is 1:1, that being 1 fish to 1 square foot of grow bed. He noted that he originally started off with 50 fingerlings and would eventually have two grow beds totaling about 48 sq ft of growing space. Problem was he never got to building the second bed due to family constraints. Of the 50 he started off with he’s now down to about 30 due to not properly screening off his pump. 20 or so poor little fish got sucked up into his grow bed and that was that.

Even so, at 30 fish he is now noticing his ammonia levels getting high. After screening for anymore dead fish, reducing the amount of feed given to the fish and his ammonia still on the high side.. the deduction is that there is just not enough biofiltration going on with the one grow bed to take care of all 30 fish (which within the span of 6 weeks went from 1 inch to nearly 5 inches!.. bigger fish = more poo = more ammonia). He is now working on plans for a second bed.

With that in mind I’m going to start with even more of a buffer and limit it to about 20 fish per grow bed.. or about 1:1.2 = 1 fish to about 1.2 sq ft of grow bed (roughly 160 fish at maximum capacity). Ultimately the main plan is to keep the system as stable as possible. I’d rather er on the side of caution then have to restart a new cycle on a system. Anyway, that’s my 2 cents.

More updates to come!