Backyard Aquaponics
A place to discuss aquaponics

Hi, I am new to aquaponics but have kept fish since I was 18. My wife and I live in San German Puerto Rico and we want to set up a system. She will be taking a week long aquaponics class in St Criox at the USVI university in June.

I am wondering if it is even possible for us to have a system that meets our requirements. We are “off grid” and can spare about 150Watts during the day but only 50Watts at night. The less electrical usage the better. The second requirement or desire would be to raise at least 1 pound of fillets per week.

If we raise Basa that would mean one 3# fish every week. I would guess that would mean we would have to support about 200#’s of fish in the system? Can that be done on only 50Watts?

Do we want to put the system in the sun or the shade? I would guess in the shade the water temp would be 78 degrees and in the sun the water would maintain 82 degrees.

Thoughts?

Thanks,

Jeff

Hum....... Full time only 50 watts. That would be tight. At least for a constant bio-load of 200 lb.

I also don't know much about the requirements of the fish you mention. I think you might get away with it with tilapia if you have lots of extra water and can use some extra power during the day beyond that 50 watts.

I have a small system that only uses under 30 watts but it probably can't sustain more than 10-12 lb of fish.
I have another small system that might support 60 lb of fish but probably uses 70 watts of pump power plus some of the aeration from the air pump on a bigger system. I suppose it would be possible to find a more efficient pump for such a system and then only run an air pump at night but would not want to leave too heavily stocked a system without filtration over night.

It seems to me that one of your requirements might need to be flexible, either the amount of fish it needs or the power usage or it might be a recipe for disaster.

You can get 12,000 litre per hour pumps that draw only 125 watts. Combine that with a 50 watt pump for overnight use, and you can probably do it. Will be tight though.

Have you looked into building/buying LED panels using only LEDs in the red and blue wavelengths? The lights are expensive but in terms of lumens per watt I think they are the most efficient and expensive way of providing artificial light to plants.

oops i realized you're probably talking about pumps >.< sorry

I use 35W to run my trout system although I also use a 25W air supply for extra safety. My system uses about 1600L of grow bed volume. A thousand litre fish tank and 600L sump. At my head height I pump about 1600L water per hour this system has easily been able to run about 25kg of trout at a time.

How fast is the grow out rate of the basa? Trout can grow to a kilo in 10-14mths from the size I get mine at. If the basa grow at a good rate you could probably do it easy with a 3000L+ of grow beds and a high efficiency pump such as this
http://www.rockaroundtheblock.com.au/pr ... 328&cID=63
Just run it flat out during the day at 65W and 30min per hour at night for about 35W. Your water turnover would be 2500-3000L per hour which should easily be enough to meet your filtering and oxygen needs.

Thanks for the replies.

It sounds like it might be possible. With a head pressure of just a foot or two it looks like, with an efficient pump, 65 Watts can pump 1000GPH

I don’t know much about Basa but they do grow fast.

Can a system be designed such that maximum aeration can take place without an air pump or high head pressure? I would think all you need is a large surface area in contact with the water and air.

Doesn’t the grow bed provide plenty of surface area?

Grow beds provide the surface area for the bio-filter and the grow beds provide plenty of aeration for the plants and bio-filter and solids filter. However, the grow beds are only aerating the fish tank water while the water is flowing from the grow bed into the fish tank. If a fish tank is heavily stocked, and the water isn't flowing, the fish can use up the oxygen quickly if there is no supplemental aeration.

Now here is a new Idea I found in another place which might be appropriate to your situation if you can find a pump that would move enough water at about 6' of head for the power you need.
http://aquaponicgardening.ning.com/forum/topics/vertical-hydroponic-components
He says they aerate the water plenty and it's constant flow.

You said your wife was attending a UVI aquaponics course? They do floating raft culture. For that the aeration is probably more needed than the water pumping.

Rupert or TC, could you kindly post here a pic or two of the "Nate Towers" tube and/or media? Do you think he'd mind?
Or maybe a new thread would be in order.
I can see a lot of words on that site, but for the photos, albums etc. all I get is blue vertical lines...
It sounds interesting.

Hey there Jeff, I'm from Camuy, Puerto Rico, Im starting to read about this so not much help here lol... but I would love to learn about your offgrid system and aquaponics... thanks

Att. Eduardo Machado
info@eduardomachadostudio.com

I would think a race way design would work best. An axial flow pump can move a lot of water very efficiently and if the water is lifted through a growbed/biofilter that is only a few inches, the efficiency can be maintained, but the plants feet may need to be wet. A shallow wide race increases surface area. Add to that water ripple, and with the intermittent full flood of the gravel oxygenation might be enough. Keeping the water clean for the fish,especially 200 pounds of fish, requires exchanging the water volume fast enough to handle the bio load.


Notice the end of this race. It provides ample space for filter media as well as clean-out.

50 Watts IS going to be a challenge. Its all a matter of moving the water through media fast enough and getting oxygen; and the oxygen demand of bacteria for 200 pounds of fish IS a big factor as well. There is a BIG difference between keeping the fish alive and keeping the water clean & oxygenated enough to grow fish well!

I have found that my system preformed MUCH MUCH greater when oxygen was added via a spray-bar; but it took 2000 gallons per hour of spray to reach point that the water cleared up and the fish started growing rapidly; I have around 2000 gallons of water( in addition to the flow through the grow bed).

If you do achieve raising 200 pounds of fish using 50 watts please post details! If you have the ability to raise fish rear around at stable temps then your best bet is to grow the fish at varying ages from birth to harvest size; this allows minimum total fish weight, and thus bio load, at any given time, but presents more challenges and work. The batch/harvest sizes of 3# per week might required as many as 26 growing areas if you separate the fish into biweekly sized batches. I have found that separating large and small fish really is important for the best possible growth rate. You may be able to group the fish for fewer batches, this requires some study.

Not that it really matters now to the original poster but would you really have to run 200# of fish? The output is 3# per week so multiple FT with graded finderlings to grown fish would work so long as you produce 3# per week. That way the load on the system is much smaller and the output is constant as opposed to flood and famine.

While you could keep the load down with this system it would be a lot more work but if power is a problem then its an option.

Worth a thought?