Backyard Aquaponics
A place to discuss aquaponics

Just getting started here. I'm planning out a system using IBCs and plastic drums and will likely have a ton of questions. I'm settling into the general CHIFT/PIST design with siphons (to avoid timers, indexing valves, etc. for now), but am still open to other options.

My reading suggests a 2:1 GB:FT ratio is optimal (for supporting the fish, at least), but perusing peoples' systems doesn't seem to bring up many that adhere to that. It looks like 1:1 or less is more common, or am I missing something?

I'm thinking of cutting 1 foot or so off the top of two IBCs for GBs and using the remainder of one for a FT and the other for a sump. I'm guessing this will give me somewhere between 150-200 gal of working volume (real-world figures are most welcome).

For various reasons, I'm not too interested in burying either tank more than a foot or so. I'll likely be installing the system on a slight slope, so I do have some vertical space to play with. If sticking to the 2:1 goal, I'll likely make the remainder of GBs from 55 gal plastic drums cut in half. I know this isn't in any way a revolutionary design, so anyone with similar (or better!) systems, please chime in.

I like the idea of an external mag-drive pump a little better than a submersible, especially for any potential cleaning and other maintenance. Ebay seems to be pretty well stocked with inexpensive used Iwaki models. Any recommendations?

The small prototype system I set up a few weeks ago (about 3 gallon FT and GB) is running at a very high pH, greater than 8 every time I've measured it. The grow bed is aquarium pepples (unknown mineral, but certainly doesn't look like limestone) and hydroton. Our water is fairly hard, so I'm guessing that's the reason. What's the most AP-friendly way of bringing down pH? I'm a biochemist, so many of the "easy" methods I can think of offhand might not necessarily be best.

Siphons can be more complicated, time consuming, prone to unexpected failure and expensive than a simple mechanical timer.


Keep reading... you'll discover there are a number of threads where someone has tried to mandate a GB:FT ratio, then there will be hundreds posts more trying to undo that BS to correctly assert the only ratio that is of any concern is the ratio of fish to filtration.


Have a look in The IBC of Aquaponics to see what others have done. Design and measure your system completely before cutting anything. Measure twice, cut once. With IBCs, in many instances, you cannot simply say you are going to cut x-inches because the IBC frame might not allow/support that cut, so the design will change.


Draw your design out (on paper or electronically) and post it here, with all the volumes and details and someone will take a look and highlight any SWOTs in your plan.


External pumps can be a little more expensive to run than "fountain" pumps, and many are not designed to handle solids (although you shouldn't be getting solids through the pump in a CHIFT PIST configuration, it is something to keep in the back of your mind should you decide to change the configuration later.) With pumps, the many forum posts relating to the issue generally have a theme that cheap pumps are... well... cheap, so fail more regularly. Remember also, you're not buying one pump, you should be looking to buy some sort of backup system too whether that be another pump or an air-blower etc.


You shouldn't have any trouble getting hold of some hydrochloric acid? Don't swing the pH too far or too fast or else the shock could kill everything in the system. Slow and steady wins the race. Once you get the pH to "some point" be aware the nitrification process could suddenly kick in and rapidly drop the pH on its own, so having a buffer material handy (shell-grits, calcium carbonate etc) might come in handy, or a volume of de-gassed "hard water" for a water change.


Scott

Thanks for the reply. I'm warming to the flood and drain system, but would like to get a little more info on timers, how prone they are to failure, and whether they're harder on pumps than continuous duty. Also, I imagine that you'd want supplemental aeration and other agitation for the FT, right? Would you also need to pump at 4x the rate relative to the siphon method (or constant flood) in order to turn over the same volume of water (i.e. the FT volume per hour) if you're doing a 15 min flood + 45 min drain? Or is that goal not as critical as it's made out to be?

Regarding the necessity of a sump for the flood and drain method, really how sensitive are the fish to changes in water level? That seems to be the main advantage of the sump, with perhaps some degree of solids settling as well.

The IBC of Aquaponics is indeed an excellent read (or several reads, rather). Very well done, Joel and Faye.