4 ms·

The sand-based system is based on Dr. McMurtry's aquaponics research at NC State University. Here are a list of publications about it: http://iavs.info/publicat

by ph0rque 10y ago

The sand-based system is based on Dr. McMurtry's aquaponics research at NC State University. Here are a list of publications about it: http://iavs.info/publications/ http://iavs.info/publications/ * In general, course sand is a great substrate for plants. Both research and my own experience show no problems with aeration or anaerobic zones forming. * The sand is the biofilter. This does form a tight coupling of the system, but does not prevent regular maintenance. For intensive maintenance, you would need to take the fish out of the fish tanks anyway. * No clogging has occurred so far because of the mesh. * What length of time is one season? What will happen after one season that won't happen after X days/weeks/months? * The water begins draining from the veggie beds seconds after the flooding cycle starts, so the water level in the fish tank only varies by ~10-15%. * How rapidly will the algae form? Two months later, I don't really see algae forming in the fish tank. There is algae growing in the furrows, but that's a good thing, since algae forms a natural nutrient battery. In any case, the fish tank placement is not optimal in my prototype, and can be improved in subsequent installations.

jsilence 10y ago
Thanks for the pointer to Dr McMurtys research. Will read. Sand might be a good substrate for hydroponics, but with aquaponics, especially when you are not removing the solids prior to flooding the beds, I doubt you will run the system at optimal performance. Regarding this and the clogging topic I'd like to know at what stocking density you have been running your systems. Our experience so far is that systems are easier to run stable with low stocking density and low feed intensity. This is a valid approach for home systems, but results in lower yields. When you start raising stocking density and feed intensity, the nutrient concentration becomes more attractive for the plants. But then solid removal becomes quite important. I am pretty sure if you simply pipe the aquaculture water into sand beds without prior processing, solids will accumulate in the grow beds. You're saying that you did not have any problems regarding aeration. Did you measure DO and nitrites? How does pH behave in your system? Does it drop, rise or stay constant? "What will happen after one season that won't happen after X days/weeks/months?" Experience from other researchers with ebb and flow show that even with gravel and LECA sludge builds up in the grow beds and that starting from the second season this can become a problem. Then the grow bed has to be dug out and cleaned from sludge. "How rapidly will the algae form?" We recently built a system (on customer request) that has a lot of light on the fish tank. Algae built up after two weeks. Massively. Again, low algea formation in your systems might be due to low stocking density. If the plants have a chance to consume the nutrients and therefore keep the nutrient concentrations low enough to prohibit algae growth, then it might appear ok. But then you are starving the plants, reducing yield.
- ph0rque 10y ago
  Let me know what you think about the aquaponics sand setup after reading the research. Edit: here's a link to a comparison of gravel and sand as the biofilter media: http://iavs.info/commercial/sand-vs-gravel-etc-as-a-biofilter-media/ http://iavs.info/commercial/sand-vs-gravel-etc-as-a-biofilte... I've only been running the system a couple months, and haven't seen any problems. Of course any system will need maintenance, but in this case, it's on the order of once every couple years. Here's the relevant link: http://iavs.info/commercial/sand-is-amazing-but-its-not-magick/ http://iavs.info/commercial/sand-is-amazing-but-its-not-magi... I don't have a DO sensor, but I do measure ammonia, nitrates, and nitrites. There were the predictable spikes in ammonia, then nitrites, then a smaller spike in nitrates that you get in a typical aquaponics startup cycle. My pH started out high (~8), and is slowly dropping. It's around 7 now. Like I said, I know my tank placement with respect to the sun is not optimal. I think the reason I haven't seen algae growth in the tank is because the water is not clear because of the sand fines. The water should clear up once the biofilm/algae gets more established in the furrows; maybe I'll see some algae growth in the tank at that point.

by ph0rque 10y ago

jsilence 10y ago

Thanks for the pointer to Dr McMurtys research. Will read. Sand might be a good substrate for hydroponics, but with aquaponics, especially when you are not removing the solids prior to flooding the beds, I doubt you will run the system at optimal performance. Regarding this and the clogging topic I'd like to know at what stocking density you have been running your systems. Our experience so far is that systems are easier to run stable with low stocking density and low feed intensity. This is a valid approach for home systems, but results in lower yields. When you start raising stocking density and feed intensity, the nutrient concentration becomes more attractive for the plants. But then solid removal becomes quite important. I am pretty sure if you simply pipe the aquaculture water into sand beds without prior processing, solids will accumulate in the grow beds. You're saying that you did not have any problems regarding aeration. Did you measure DO and nitrites? How does pH behave in your system? Does it drop, rise or stay constant? "What will happen after one season that won't happen after X days/weeks/months?" Experience from other researchers with ebb and flow show that even with gravel and LECA sludge builds up in the grow beds and that starting from the second season this can become a problem. Then the grow bed has to be dug out and cleaned from sludge. "How rapidly will the algae form?" We recently built a system (on customer request) that has a lot of light on the fish tank. Algae built up after two weeks. Massively. Again, low algea formation in your systems might be due to low stocking density. If the plants have a chance to consume the nutrients and therefore keep the nutrient concentrations low enough to prohibit algae growth, then it might appear ok. But then you are starving the plants, reducing yield.

ph0rque 10y ago
Let me know what you think about the aquaponics sand setup after reading the research. Edit: here's a link to a comparison of gravel and sand as the biofilter media: http://iavs.info/commercial/sand-vs-gravel-etc-as-a-biofilter-media/ http://iavs.info/commercial/sand-vs-gravel-etc-as-a-biofilte... I've only been running the system a couple months, and haven't seen any problems. Of course any system will need maintenance, but in this case, it's on the order of once every couple years. Here's the relevant link: http://iavs.info/commercial/sand-is-amazing-but-its-not-magick/ http://iavs.info/commercial/sand-is-amazing-but-its-not-magi... I don't have a DO sensor, but I do measure ammonia, nitrates, and nitrites. There were the predictable spikes in ammonia, then nitrites, then a smaller spike in nitrates that you get in a typical aquaponics startup cycle. My pH started out high (~8), and is slowly dropping. It's around 7 now. Like I said, I know my tank placement with respect to the sun is not optimal. I think the reason I haven't seen algae growth in the tank is because the water is not clear because of the sand fines. The water should clear up once the biofilm/algae gets more established in the furrows; maybe I'll see some algae growth in the tank at that point.