Backyard Aquaponics
A place to discuss aquaponics

It filters like this..

The beads float up. The water flow up through the beads and as it does the beads pack together. The small spaces between the beads become the filter. When bubbles "biol" up through the beads its causes them to separate and release the trapped stuff and the water flow downward pulls the released junk downward. The bubbles also turn and toss the bead around a bit causing gentle scrubbing. The dirt water is sucked down into the air container. While the air slowly builds up over the next few hours the solids in the water settle downward where they can be drained out.

Quick update on the bubble washed polygeyser filter I made. I had to take it apart in insert a screen in the water return line because the excessive bubbling and water draining was sucking all the beads into the bottom (air) tank. Now, I just how the screen does not plug with poop and bacteria growth.. Im really not sure how the commercial version would have overcome this problem without a screen... They did not put that in the patent. Perhaps their down flow area is so large that it does not draft beads into the air pocket...

Weather is down as low as 36 at night now, so its a good thing I have the filter working. Just have to get it cycled in the cold as I did not get it cycled before the weather got cold. So that means I have to deal with ammonia and nitrates again

..nitrites even..

What are temps inside your shed like, or are all the fish in the house?

The fish are inside the shed which has a 1 inch coating of poly foam sprayed in. I have a pellet stove on a thermostat that keeps the temp in the shed at 65F ~18C.

Pellets cost $4 per 50 pound bag and a bag heats the shed for 4 to 13 days depending on outside temps. Im not sure if this is saving much money over electricity; I assume it is.

At least you are keeping condensation at bay?

Its not humid in the shed at those temps, but with a sealed shed warm days can cause a bit of moisture on the windows. I just open the door and it dries out in no time.

There has been some talk about the dangers of pumping fish water through glude pvc pipes. Well, I can tell you that tilapia seem to have no problem with it. I glued a join above one of my tanks and about 3 drops of fresh glue fell in to the tank. I scooped it out when I noticed and the fish don't seem to have noticed, lol. So I'd say glued pipes if not glued excessively would be ok. Not sure who that affect health in the long term, but no worries.. I had to do a water change while the weather is cold and the new bio filter is cycling so its all clean again..

Speaking of water changes.. My well water is just about the same temp as the fish water so I don't even have to warm my water when doing changes.. convenient..

Dan, 1 pellet stove alone won't justify a pelletizer but if you heat your home as well and it also makes animal feed pellets like for your tilapia and if you keep rabbits it may be worth the investment.
http://www.pelletpros.com/id68.html.
I would really like to do more with my lawn clippings!

There is a video link on the top of the page to see it run. It's a noisy bugger.

That is an interesting idea! I could dry and pelletize my soldier flies mixed with veggies.. Or algae for the winter...


That brings up another issue I hope someone can help me out with. How large of a pond would be required to produce 12 grams of algae? I'm thinking I might include an algae pond this spring so I need to decide how big it would need to be to feed 250 tilapia.. Can anyone point me to a source of info that will tell me how much algae grows per square meter?

It will be disconnected from the fish system at night to avoid oxygen and pH problems.

Hi Dan
I've researched a bit what you've asked and it seems that spirulina is produced at a rate of 10g/day/sqm on a approx depth of 20cm.
But it needs a fair bit of fertilisers and can't be connected to the system on a daily basis, as it seems that the algae decomposition in growbeds diffuses toxins for the growth of algae.
This link is where i found the info but it is in french, but the data is universal. Good luck and i'll be very interested to see how you can process and produce your needs of fish food.

orry forgot the link: http://www.electron-economy.org/8-categ ... 86945.html

Thanks Amacafish! That is very helpful.

Ok, so it needs to not be connected to the system, at least for that strain of algae. Now I am pondering a photo bio reactor like used to produce algae for oil. I could produce the algae there and dry and pelletize it for food.. But how to collect the algae...

I really want to feed my fish algae. I ran a test with a single tilapia in algae water. That tilapia grew just as fast as my fish on commercial fish food and looked a lot more healthy with better body coloring. Plus, with farm raised tilapia the omega 6 is to high to be healthy to eat all the time (joint swelling) and the fact that algae pellets are very expensive, it seems that I must use a natural alternative. Now armed with the knowledge of production rates I can size a feed system. I have fish water, pee, and cow dung, I hope I can feed the algae from just that and not have to buy commercial fertilizers.