My first system: Raft converted to Chop Charcoal Media Bed

[Paul Letby]

Hey Gang!  Thought I'd share my setup with you.  It's not pretty but it works.  I chose to enter aquaponics to keep my water change bill down as I was 'fish sitting' this winter.  My neighbor needed somewhere to keep his fish after he closed his pond so I agreed, seeing as I had a 30 gal tank with almost no residents.  I never saw more than 10 goldfish at a time so I figured I was good. Not so.  His water was so full of algae that I never saw all 60 at once!  That put me into emergency mode and I dragged my 55 gallon rainwater barrel into the basement and set up a filter with powerhead. 

After the two tanks cycled I realized that I'd have to do water changes very often to keep nitrates down.  Then I thought about aquaponics!  I'd seen the idea before, but never really considered it because an outdoor setup around these parts would only run for maybe 4 or 5 months out of the year before freeze up.  I did have a light stand in the basement with the barrel though.  So I chose the raft system simply because I had rafts on hand from messing around with hydroponics last year.  I grew lots of lettuce, but didn't like flushing old nutrient down the drain.  Now I don't have to worry!  I built the GB out of lumber with construction poly as a liner, ran some plumbing from the barrel to the GB, found an off season pond pump at the local home improvement box store (75% off!) and rigged it up to pump back into the FT.  Drilled lots of holes in foam to fit pudding containers I drilled more holes in and filled them with gravel, plopped them into the holes in the foam and plunked seedlings into them!  Confused yet?  I am.  Plugged in pump and watched!

Oh yeah, almost forgot.  To keep nitrates down in the 30 gal fish tank, I used some previous experience with aquatic plants to handle that.  4 weeks ago all my aquatic plants in there were just sprigs, except for the sword plant, but it's grown alot too.  I mixed up my own fert (micronutrients, P, K) so that the limiting nutrient would be nitrogen, and so far so good.  Only have hard scale algae at present, and that's very slow growing.  I'm not sure if I need the CO2 injection with so many fish.

Nitrate is almost unreadable for a few weeks now in both tanks.  It was quite scary high before the plants got going. 

Anyway, here's some pics for it all to make sense!

Here's an overview of basement system:

Lettuce view:

30 gal tank upstairs at feeding time!

[Chi Ma]

Awesome Job!

[TCLynx]

looking forward to some more pictures when you get a chance. Curious to see what the bed with the charcoal looks like and how dark your water has gone (will be interested to see how fast it clears back up too.)

[Paul Letby]

Thanks for the kind words everyone, I'm glad someone's reading this! Today I made another batch of charcoal and added it to the bed. It's still not full by a long shot, but it doesn't float as much now that there's some more weight on top. In fact I had to add a gallon of water since last night to keep the water level the same, so it must be getting into the charcoal. These pictures are from yesterday, so there's more charcoal in there now.

The water got pretty darn dark for a few hours, pretty much opaque. I could see about a quarter inch into the water, with a flash light about an inch. I did this in the evening, and by morning it was nearly crystal clear, so it didn't last too long. Fish didn't seem to mind, they were still hitting the food hard.

I still have to tidy up the edge of the liner, got excited about getting water in. :)

Here's a few pics, sorry didn't get the black water.

[George T]

Have you tried rinsing the charcoal before adding to the bed? I see that you're not crushing it. Certainly there are many small particles, even when it's not crushed. Have you kept track of your water tests? Thanks for the updates. GT

Paul Letby said:

The water got pretty darn dark for a few hours, pretty much opaque.

[Paul Letby]

Hey George. No I didn't rinse the charcoal first, and I figure this size is kinda nice. I did break up the big bits. So far my pH is steady around 6.8. Haven't done ammonia cycle tests for a week, I'll post results when I do them. Once I have finished adding charcoal I'll adjust the pH if it's still this high. I'm thinking the charcoal may do that for me.

[TCLynx]

pH of 6.8 is what many people would call a perfect pH of aquaponics. 6.5 is usually the time to add buffer to keep it from dropping too low.

[Paul Letby]

Cool, I'll just be happy that part of the system is sorted then. Thanks TCLynx.

TCLynx said:

pH of 6.8 is what many people would call a perfect pH of aquaponics. 6.5 is usually the time to add buffer to keep it from dropping too low.

[TCLynx]

Just make sure to keep some lime or shell grit on hand to add if the pH starts dropping too much

[Harold Sukhbir]

Hey paul...you did it! Soon you'll be known around here as the "Charcoal Guru".Please keep posting.

[Paul Letby]

Argh, "Charcoal Guru", now that's funny.

Harold Sukhbir said:

Hey paul...you did it! Soon you'll be known around here as the "Charcoal Guru".Please keep posting.

[George T]

If it keeps your inner firebug entertained - that's the important thing. Seriously, I am curious as to the nitrifying capability of charcoal media, therefore my earlier question. If you have before and after stats, it may be relevant.

Paul Letby said:

Argh, "Charcoal Guru", now that's funny.

[Paul Letby]

Made another 5 gallons of charcoal today, actually it's probably less as I mixed it with snow to extinguish it.  After it melts I'll probably have 4 gallons.  I got to help the neighbor boost his car while I enjoyed my toasty flames in -24 C weather.  I must have looked funny warming my cold feet by taking them out of my boots and holding them up to the fire with them steaming away as I sat in my lawn chair.

 

  I finished the bed today by adding strips on top to capture the liner, then trimmed the liner.  I figure a couple more fires yet to fill the bed.  The charcoal is still absorbing water, 2 more gallons today to top up the system.  I'm noticing that the flood cycle is taking much less water as more charcoal sinks and displaces water.  Good thing, as initially the system was using almost all the water in the sump to fill the bed and I was worried I'd goofed.  Now I have much more wiggle room.  As I add media I will extend the stand pipe just a touch higher to maintain a 2 inch below media level.  For now it'll stay as it is.

 

 

 

Still filtering the big chunks out, not many now.  As more charcoal sinks it'll be less of a problem I think.

 

 

I re-installed my shelf to keep the african violets happy till they go into the grow bed (as there's no where else for them!)