I decided to change the pipes out, again. Yes, this is the second time. I used 1/2" PVC in my first build. Then I upgraded to a 1" o.d. irrigation pipe (3/4" i.d.) to increase the flow. That was a huge improvement, but it was nothing compared to the latest upgrade to a 1-1/2" i.d. pipe. That's a big pipe, and the flow rate is awesome! The pump manufacturer for the pump (it's a Danner mag-drive "12") recommends 1-1/2" as a minimum to achieve the flow rates they publish, which is why I decided on this size. I do not know the exact formula, but I am fairly certain that flow rates are proportional to the square of the radius of the pipe, so going from 3/4" to 1-1/2" should result in about 4X the flow, all else being equal (which it probably isn't).
In any case, the increased flow rate keeps the fish tank water much much cleaner. That also means there are a whole lot more particles making it to my gravel grow beds, where they can be mineralized, rather than staying floating around my tank, where I am not so sure what happens to them biologically and chemically speaking.
Here's a vid describing the change-out where you can also see the puurdy new pipes and fittings, and appreciate the super-duper water flow(!):
Also new this week are 5,000 (could be 1,500 or 10,000 or 8,000 - I really couldn't say) new workers and they all fit in the picture below. This is the latest addition of our amazing friends, eisenia Fetida. I had added red worms to the system a few weeks (month?) ago, but I also set up some Red Composting Worm bins at home and at the farm with the same batch, so I was a little short with what I added to the beds. Also, upon reading that they take 60 days to double in population, and being as impatient as I am, I decided to add more the easy way - buying more.
These were added at night simply by placing them on top of the gravel beds. They moved in and under the gravel fairly quickly. From what I have read about these worms, aquaponics gravel grow beds should provide near-ideal conditions for these organisms.
The purpose of adding these to AP systems is so they assist in breaking down organic solids left in the beds. This mostly consists of undissolved fish waste particles but there are also plant roots, dead leaves and ocassionally fruit that falls off and does not get picked up. The gut of these worms contains several times more bacteria per volume than their surrounding environment (I read somewhere 13X more) and those bacteria are able to digest a myriad of organic components, some of which we may not even know of or yet understand. Their metabolization of these compounds releases simpler compounds or elements back into the system - many of which can then be used by the plants. Red Worm compost and Red Worm compost tea are valuable fertilizers and there is actually a market for them where farmers pay good money for them. These worms will be producing the same compost and tea right in the grow beds, 24X7 in what is probably very close to an ideal environment for them. I recently also read that Will Allen at Growing Power, uses red worms in huge quanitities in their systems.
Finally, as mentioned in the video above, I began to set up two vertical grow towers above one of the gravel grow beds. These take great advantage of vertical space and my goal is to grow strawberries with these systems. That in fact was one of the main reasons for changing the pipes out. I got the towers built, and if you want to see how they are put together, see the video below. Unfortunately, I still cannot get water up to the top of the towers! That was a slight dissapointment, and I'll have to figure out a solution. The towers are nice though, and I can't wait to get them working!