Pond Boss Forums INTRO Questions & Observations RASers anonymous

How high are they able to lift that much water with air?

Yes and I am still getting a thick silt passing through to bio ball tank. I may be overestimating what this should remove. I plan on adding a DIY 100 micron sieve before the settling tank to help out. My biggest problem is that I did not put in bottom drains. But when I drain and clean after the third year I will be putting them in.

Brian,

Mine won't be lifting 1.7 meters. That is the height of the tube for optimum lift but the water will automatically be that high due to the container mbbr it's coming from being that height or nearly that height.

Ahh. I can see how one could get really great results using air to pull water through a filter that is enclosed and below the tank water level.

The challenge with aquaponics is that you have to move water through open topped grow bed which usually causes some amount of head height. For you to have close to zero lift i guess you are doing constant flooded grow beds or rafts? I figure that could be an extremely efficient design for commercial system(s)

Is that container that high? 5'-6"? Maybe I'm thinking of the deer netting container.....

Ok I think I follow you on the air lift.

It isn't lifting the water 1.7 meters. The optimum flow is achieved when the air has to raise that distance. Correct?

there's tradeoffs to both styles of aquaponics and in some cases it's just personal preference. I understand why you would prefer the raft technique because it is so similar to traditional RAS and your fishkeeping background.

1.) There shouldnt be any sludge or buildup in the grow beds. people who have this problem have too many fish for their biofiltration.
2.) continuous flood of grow beds is fine as long as you maintain good DO levels in your water. Some people i trust say they have done both flood and drain vs constant flow side-by-side and tell me that the the constant flow outperformed flood and drain. I use ebb and flow because i feel it guarantees that anaerobic zones cannot form in my grow beds. My pump is always on though. I use a siphon technique to manage the flood and drain part.
3.) not sure what media you have to clean up after harvest. I pull up the plant with it's roots.. shake off the media and kind of smooth it back with my hand.
4.) water is heavy too but if you are talking about setup, it's a lot easier to fill a grow bed with water than 1.5 cy of rock, i will give you that.
5.) what do you mean by raft safety net?
6,). In 110 degree texas summers i dont think i can get away with no diffusers in the fish tank or in a raft grow bed. Your results may vary.
7.) It is true that commercial systems dont use gravel grow beds. But a backyard system has very different goals. I would also point out that contrary to your position "aquaponics system should be treated foremost as an aquaculture system with plants as an add on", the successful commercial aquaponics systems seem to focus on the plant production and the aquaculture portion is a very distant second. In some case like bright aggrotech they say they do not sell their fish at all. They say they will give them away to employees or customers that have shown interest.


Why i use gravel grow beds:
1) it's lower maintenance. Since i dont have a traditional ras type filter, my solids go into my grow bed and are broken down over time. i never have to clean the filter or back wash
2) None of the fish food is wasted. The solids begin breakdown in the grow beds with red wiggler worms... and then they mineralize in my grow bed as the micronutriets dissolve back into the water over time. The only mineral supplement i should ever have to add to my system for the plant health is some cheleated iron... and only rarely.
3) I can grow a wider variety of plants. You can do okra and probably corn in a raft system but you are probably going to have challenges when the wind blows. Having substrate for the roots to latch onto helps the plants stand upright and grow tall without any hassle. I could also do trees. I just planted a banana plant.
4) it's lower maintenance. i already said that but this point is in a different way. I can just buy a pack of seeds (or save them from last year)and throw them in my grow bed and expect them to grow. With a raft system you are going to have to buy your plants or grow them in a separate container or seed starter.
5) it's lower maintenance. oh this one again.. Typically the nitrification process that converts fish waste (ammonia) into nitrates (plant food) leaves negative electrons behind and over time will lower the water ph. From time to time someone must add something to bring the ph back up. My substrate is slightly alkaline and buffers my ph (albeit high...about 7.8), i never check my ph and i can tell you any minute of the week what my ph is. i never have to add chemicals to adjust it.

There's a soft spot in my heart for rafts too. Before all is said and done with my large outdoor system i will have a large raft section. The water will flow fish tank -> gravel beds -> raft.

The summary is i use gravel grow beds because "I am lazy".. i really enjoy the design and building process but when it comes to managing the aquaponics system. I want to throw seeds on the ground, feed fish and pick veggies. Eventually i will most likely automate the fish feeding part too.



brian

lol, you cant be proven wrong.

What about worms in your media?

?

As an advantage or what?

I'm skeptical of some of those school systems. Some are so terrible it's a good thing they are using a forgiving species like tilapa. I haven't seen it but I was told a system FFA was pushing was terrible too.

So I have done some research on aquaponics and I'm not real interested in the growing veggies to sell but I like the idea of taking nutrience out of the water.

My question to the experts is what plant woul be the best at taking up nutrience? It does not have to be edible.