Backyard Aquaponics
A place to discuss aquaponics

As I said above the one I used to retrofit my tank is the one that comes in from above. That one I know works because I've done it. The other I don't know. From other things I'be done I'm pretty sure it will work as long as the center pipe is long enough so that it cant be knocked off and can't be knocked and caught at an angle.

Something I forgot to add to the drain that goes through the side of the tank is a coupling near the tank wall and near the elbow above the drain "foot". When you want to net the fish out the horizontal section can be removed and the drain reattached near the wall of the tank. This gives you a clear tank within which to work your net and be able to drawn down the water level in the tank.

M1 of my version of this just had the down section removable which was a major pain in the neck when trying to net the tank. Before the next netting I'll be adding couplings so that the hole assembly can be removed when harvesting the tank.

Thanks for compliments but other than the drawings of how to do these things with off the shelf parts there is nothing original there. All of this information is out there to be found or bought. For example almost all of the above information is in the book by Timmons and Ebeling "Recirculating Aquaculture".

Anyway I hope it helps. Many BYAP systems could easily improve their results by designing systems using the information which is all standard beer to the AQ industry. Don't get me started about many so called commercial AP systems and their complete lack of awareness let alone understanding of many of the above design considerations.

Their is debate on this. The extremes are just one jet per tank to in the case of MCRWs four jets per cell.

In AQ even very large round tanks (42m diameter) only have one sparger with multiple jets. On the other hand almost all the MCRWs have at lest 3 spargers per cell. It might make a difference but I don't think anyone has done any research to check.

Stupid timed edit function



The above should read:



Sorry.

I would invest in bulkheads if plumbing larger tanks, especially for bottom drains.

Makes sense, you lose enough pressure from the T that the difference can't be much.

Currently, my water enters via a homemade trickle tower/bakki shower made from a few 5 gallon buckets, but I have no idea how much DO I'm adding, I may be just as well off with a jet at an angle on one side to get some swirl.

Not sure what you mean by this?

If you T your line so that you now have 2 inlets on opposite sides creating swirl, each inlet is less than half the flow of what you would have if you had left it as one inlet. So I would guess that if 2 or 4 inlets is better than 1 it probably isn't much difference. At least not enough that anyone has decided it is worth researching.

Unless the research is done you wouldn't know.

For example it was assumed that in a MCRW there would be "dead" zones. Areas of little to no mixing where metabolites from the fish would build up and dissolved oxygen would go down. The researches who first studied this MCRW were doing so to find out how big the dead zones where not whether they existed or not. To their surprise their were no dead zones.

To date I only know about research to investigate this in 3 cell MCRWs. I'm pretty sure we can assume that there won't be dead zones in MCRW that have more than 3 cells and we can probably assume that two cell MCRW won't either. What about 1 cell MCRW or rather as they would probably be better known square tanks. It would be reasonable to assume that their woudln't be but you never know. Scientists often cop flack for studying things that we already "know". Often it turns out that we did know but every now and then you get surprised and get a result that is at first completely counter intuitive.

Stuart, how big is your drain? 90mm? Assuming that would also be the size of the bottom drain (if using that method)?

nevermind

Hi
Great thread. Thank you.
RE central SLO
Just a thought.........
If you cut a horizontal slit at water level in the vertical down pipe it would become a ‘Skimmer” Very common in swimming pools.
Possibly add a non return valve say 15cm below water level.
Clean up the low life and the floaters!
Titus

Ehh...no.

The drain needs to be sized appropriately to the flow.

This thread covers how to work that out but in summary...

Too small a pipe increases the friction losses unnecessarily, too large and the solids will settle in the pipe.

http://www.backyardaquaponics.com/forum/viewtopic.php?f=14&t=21129&hilit=xtutex

Wow! That's a good read! I think I understand (at a basic level) the concept and calculations. Will read it another twenty times while I'm getting everything else sorted then try my hand at the actual calculations.

Awesome thread! I am designing a custom in-ground liner pool for my ducks (that will also be an aquaponics system to grow duck fodder among other things), and had questions on this very topic.

My design is a "modified raceway" wrapped around a circular "island". The main inlet will essentially be a wide, shallow "stream", and as the raceway wraps around the island it will become narrower and deeper. Additional inlets from grow beds or other features will spill into the pool at various locations around the perimeter. The pump will be located at the deepest, narrowest end of the raceway. I've attached a basic Paint drawing to illustrate the general idea:



If dimensions are important, let's say it's 4' deep and 2.5' wide at the deep end (wider at the top), and 6-8' wide at the shallow inlet (just guesstimates at this point).

Considering the several inlets pouring in around the perimeter, my guess is that the radial flow will tend downward around the perimeter, and upward on the "island" side of the raceway. Does that sound correct?

With an idea of the radial flow direction, what would be the best placement for the pump? Low or high? Inner wall, center, or outer wall?

Any other thoughts or suggestions? Any input is much appreciated!

Think best place for the pump may be in a sump away from the duck feathers and dirt.