Backyard Aquaponics
A place to discuss aquaponics

Greetings all,

I have begun an attempt at Aquaponics in Christchurch, New Zealand. I am using Chinook Salmon. I have 200 salmon in a 16,000 L pond. It is quite cold here, about 5 deg C in Winter, 15 deg C in summer. But already my pond is murky green in colour. There is a lot of plant life in the pond, and some goldfish.

I currently have only a small 3000L/h pump/fountain plus a 1500L/h pump supplying some grow beds.

It would appear from calculations in this forum, I should really be pumping 16,000L/h, and have 5m3 of grow bed.

I have a some questions:

1. As the scale of the pond increases does the requirement for water turnover become less critical? Does it really depend on the number of fish, or the size of the pond? I could take out some fish if need be. Could I get away with 8,000L per hour?

2. What is the most energy efficient way I can achieve the required turnover? I was looking at a Laguna 4200 pump, but would prefer to get away with less electricity consumption if I could.

Many thanks.

The Lagunas are pretty good. There are some other pumps that are better at lower heads I think they were Oases pumps.

Best pump not only depends on desired flow rate but Total dynamic head

Based on the title of your thread I was intending to post this pump.

Check out those efficiency curves!

Thanks, but I can't manage to read that. Would you have a higher resolution image? Is that a chart for a particular model pump? If so can you tell me the model please. That would be awsome.

Cheers

Olly

I thought I would angle a 40mm pipe very low and have it just poking out of the water, so minimise the head, just blast the water across to the other side of the pool to pick up some air on the way. I guess this will create a little dynamic head, I couldmake the pipe bigger, but then I guess I would get less airation.

I looked on the Oase website, and the power consumption at low head looked pretty similar. The main difference seemed to be the price. It was more than double the Laguna price! Wow weee.

Hiya..

Let me pipe in..

A 16,000l system..

At a suggestion.. you need to have at least 16,000l turn over every hour..
- you need the high flow rate to help the system.. it also help to keep the system air rated.. it also help to keep the system healthy..

Can you supply a few pictures of the system..

With 200 fish.. you need to keep the air up to the system..

Juergen

I've been offline for while so sorry for the tardy replies.

Forum won't allow posting of higher resolution pictures.

The performance curve is for a pump that can deliver 80L/s at a TDH of 4m with ~80% efficiency.

So with a lower TDH it would probably turn your tank over more than 20 times per hour

I was being silly.

From memory the Laguna 11000 was the best pump for a TDH of around 2m where as one of the oases pumps was better between .5m-1m TDH.

The laguna 16000 is not big enough to turn over 16000L every hour because it only barely produces 16000L/hr at 0m TDH. Two Laguna 11000 pumps would do the job though. Especially is you kept the TDH down.

From what your are saying though you want to create a fountain?

http://bee.cornell.edu/cals/bee/outreac ... wnload.cfm

If your aim is to aerate checks this out.

What about using airlifting?

Going back to the original post.

How did you arrive at a figure of 5m3 of GBs?

How are the GBs installed? Are they installed?

The Laguna 4200 you refer to is that gallons? ie is it the equivalent of the Laguna 16000?

Sorry I didn't check this post for a while. I am down to 150 fish now, I lost 50 in the first spell of hot weather before I got the pump installed.

In answer to various questions: The Laguna 4200 is the 1600L/H model. Seems to have slightly different names in different markets. I have bought it now.

I have since set up a 40mm pipe with holes squirting small streams out for about 2m, going into a barrel with a second barrel on top, creating a head of about 400mm. The lower barrel holds the filter media (which I am still trying to source). I am planning to chop up lots of garden hoses for the media.

I have given up on making big grow beds, and am thinking of using rafts of polystyrene with little pots in holes in it, with the surface about 50 mm above the water so that air can get between the raft deck and the water surface whilst still providing shade.

The puzzle I have is this: If I just drain out half the water, then I have the same surface area, so the same amount of exchange of oxygen with the air. Then I could claim I had 2x turnover per hour. Would this be better? It doesn't really seem logical, why does extra water require extra turnover? The number of fish and plants hasn't changed. Is it stocking numbers or water volume that ultimately determines the required flow?

I have the course text and it's the best recirculating AQ engineering course I know of. It covers AQ well.

The pond turnover is determined by the amount of ammonia produced by the protein digested. With your stocking, you will need more than a 16K turnover. and a very effective filter system which includes a bio-filter supplied by an effective particle filter to keep the bio from being dominated by hetrotopic bacteria rather than saving the space for nitrifying bacteria.

I suppose an AQ system would best be set up for the growing bed to serve as the main particle separation with finer particle filters following. after adding oxygen to the flow again, send it to the bio.

An air pump can be designed that's more efficient than a conventional pump and adds air at the same time. Air pumps can serve a very low head but at low heads they pump a lot of water. Another thought for AQ is a guyser pump that can provide the high heads and flows needed. They move the water after building up a chamber of air and send it all at once but that can be dealt with, especially in AQ.

Do a search and get an idea of how they work; you may like them!