Backyard Aquaponics
A place to discuss aquaponics

DWC with suspended cups

A welcome guest

I had 2 different styles of DWC (in IBCs) going. One way was via a floating raft and the other was suspending cups with the bottom 1/3 of the cup in the water. I was unable to get anything to grow in the floating raft. I would transplant seedling after seedling and all would appear to wilt and then die on the raft. I had a little better success with the cups as I used these for both seedlings and rooting cuttings with modest success. The plants would grow; however, on these most did not flower and the ones that did did not set fruit (non fruiting plants like lettuce, kale, would not grow in either).

The next few posts will be of the challenges that I have had during the first year (2017) of "The Quad" (the number of FT in play).

I set up a half barrel as a mini dwc. I was using this for growing duckweed. It worked great, even during summer (once I put a sun shade over it). Well, one morning, going out I noticed "something doesn't sound right." The sump tanks were nearly empty and the pump was gasping as it was receiving just enough water for it to cough from the draining grow beds. The ground was flooded. I pulled power to the pump. The mini dwc was overflowing. The culprit turned out to be a lizard blocking the drain! Cleaned the drain, filled up the sumps, and turned the flow rate down to a trickle (the duckweed didn't need any more flow then that anyway). The pump did not burn up and the mini dwc did provide me with a constant flow of duckweed for the tilapia both before and after this drama.

This was very insightful and proved to be true several times!! If the ground was wet and the sump tanks were low...the bladder would collapse in. If there was a leak and the sumps ran dry...the bladder would collapse in (due to the dirt pushing in on the bladder). I should have reinforced the IBCs when this was suggested; however, at the time I did not want to dig back out or add any more material to the sumps. I realize this was one of those suggestions that should have been acted upon immediately!

Leaks happen...A lot!! As expanding, changing, working out the kinks cause you to learn the system...something will happen. More often then not it was either a leak or an overflow-small, medium, and large. I have had a lot of them! Over the course of 2017 I have had to do a complete fill in the neighborhood of 6 times, and partial fills upwards of 11 times (not including top offs due to evaporation).

Is your DWC aerated? Just wondering if you figured out why the plants were dying?

I hope 2018 has been better. That's weird about your DWCs. I didn't get mine to work very well the first year because of nutrient deficiencies. Spays with potassium or iron helped. Our issue was paleness in leaves, which looks like is happening again albeit to a lessor degree. Also the pH of our well water is high like 7.8 to 8 once it hits the air. It seems that adversely affects mineral uptake as well. I did add air as Scotty435 suggested to the DWC at some point in 2017 which helped to keep the roots clean as well as distribute water up into the pinch pots.
I'm ready to make big changes in our system plumbing too. Here's to "No leaks!"
Best of luck to you!
Brian

I am not sure why the DWC was unsuccessful for me. I had 4 air stones in each IBC DWC (one in each corner). I found some small KOI in each of the DWC when I was decommissioning them (there was koi fry mixed in with my mosquito minnows and they flushed through the entire system!) but the roots did not show any signs of being eaten, in addition no plants in the floating rafts lived, while plants and cuttings did live in the cups (albeit not productively). The rafts came from an organic farm and were used for seedlings (I still washed them thoroughly before use). I am suspicious of 2 things. If the rafts were reflecting to much light on the seedlings (they are white and were blinding in full sun) and overheating them, this doesn't explain the lack of productivity from the cups, though. Or the swirl filter not efficient enough (when I decommissioned-converted the tanks this year, I gave them a thorough cleaning and there was a LOT of sludge on the bottom of all).

This year I have converted 2 of the 4 IBC DWCs to flood and drain gravel beds, the other 2 IBC DWCs I have relegated to duckweed as I have a LOT more tilapia this year (I converted the old half-barrel duckweed barrel to a gravel flood and drain). I have also updated/changed all plumbing going in and out of these.

2018 is looking really good so far. I have a lot of changes both done and planned (haha, but don't we all!). I am looking forward to finishing bringing this post up to date and sharing all that is happening.
I am on an artesian well from the Florida aquifer, so we not only have high PH but we have very hard water as well.
Good luck on the plumbing!

Even though I am in Florida, where we are at, we still get cold. And we got several instances of cold in the 2017-2018 winter season. Other then the few koi that I got mixed in an order of mosquito minnows, my system is powered by tilapia. As tilapia are warm water fish, I was hoping that with the buried sumps and the volume of water I have, I would have a buffer for when the temperatures drop. I did have a buffer as long as the temperatures didn't stay dropped for over 2 days. Unfortunately, the temps did drop to freezing and stayed there for upwards of a week and not just once but several times. This caused my system water to drop as well. In the 50's, the tilapia get fairly lethargic. If you bring the temp up, they can recover. In the 40's you have mass loss. Aquarium heaters are not sufficient! I have tried in tank, too much moving water. I have tried external, flow rate too great. I tried boiling water and adding to sump, takes way too long, uses way too much fuel, and does way too little in temperature rise due to how many gallons I have to raise.

I achieved my best success with isolating one tank (shut down flow in an out - left aerator running) and surrounding it with wall insulation (hard foam panels) and then placing 2 heat lamps pointing down into the tank. The fish would float under the light trying to soak up the heat. This kept the tilapia limping along until the temps bottomed out at which point I harvested 60 tilapia (after they had succumbed to the cold). I did have 20 tilapia actually make it through and are currently growing out. I also brought 5 select tilapia inside when temperatures started getting really bad to the newly created tilapia love shack. I am proud to announce that I have added 80 fingerlings back into The Quad.

I now am in need of closing the tilapia love shack as I have an additional 110 fry growing out and a couple fish look to have eggs in their mouth.

A few people have built heaters here using water heater coils and PVC pipe. I think there are instructions on YouTube. That kind of heater might work for you. I use a stock tank heater but I only have to keep the water above freezing since I'm growing Bluegill - this sort of setup wouldn't come on early enough for your situation. Here's one with an update that runs through the whole build - https://www.youtube.com/watch?v=YQ8vUUpwYgU The update is about using CPVC in the portion where the heater is.

The DWC situation is interesting but at this point I can't tell much. I do think you should give it another try though. The lack of flowering suggests that you had high nitrogen levels but if other plants wouldn't grow then there's more to it than that - might just be a lack of nutrients because of the filtration. If that's what happened you'd either have to add nutrients or put in a mineralizer to reclaim the nutrients from the solids you removed. Who knows, that could be it or not . Post up some pics if you try the DWC again and start having troubles .

I saw the home built heaters using water heater coils (when temps started dropping, I started searching for any solutions) but decided against it out of concern of heating up the pvc near it and leaching chemicals and the electricity usage.

I have considered bluegill, how has yours turned out (i.e. size/amount of meat per fish, taste, grow speed, hardiness, etc...)?

I might try DWC in the future (I have the 2 IBC duckweed tanks that really are DWC with just duckweed growing), right now I am waiting to see how the gravel flood and drain of the quad perform in year 2 (2018).

I have had several people (outside of the aquaponics culture) voice their concern with eating the fish from aquaponics. Opinions ranged from the fish meat being mushy due to lack of free range swimming to the meat tasting overly fishy or dirty/earthy because of the small (compared to nature) closed loop of the water. I saw (on Backyard Aquaponics as well as other sites) several people advising of "flushing" the fish that they are going to harvest to remove off flavors/smells and I had prepared to due just that. I have another IBC fish tank cut and painted (identical to the ones plumbed in) that is sitting empty and not connected solely as a flush out tank. The idea was when I was ready to harvest the fish, I would fill up the tank with fresh water, throw in aeration, net the largest fish and add them to the fresh water tank, wait a day, then pull the fish from the fresh water tank and prepare them (either fillet or whole) for the freezer.

Well, the weather forced my hand and I wasn't able to due this. Instead I harvested straight from the fish tank. I can't say enough positive about the quality of the fish (except the size). I filleted all of the fish I had to remove and froze the fillets for future usage. From the fish I cooked immediately to the fish we ate months later, the results were the same. The flavor was the cleanest tasting fish (of any type) that I have tasted. The texture was firm, but not tough. I can't help but point out that MOST of the tilapia I have purchased from the store (your pick I have purchased from multiple companies) have had some form of "dirty" or "earthy" flavor with them. Also, the tilapia purchased from the store can be on the "softer" side of firm, sometimes in the "mushy" realm.

Last, but the most important, is my family (wife and children) all had the exact same opinion and enjoyed the fish tremendously!!!

The tilapia (outside of being smaller then I would have liked) was a big score on the first year of the quad!