Backyard Aquaponics
A place to discuss aquaponics

As has been mentioned, adding a sump tank does not mean more pumps. It can mean more pumps but not necessarily. 1 pump in the sump which pumps to your fish tank which overflows, using gravity you drain your water to your grow beds and then drains from your grow beds to your sump via overflow or siphon. No additional use in power, just a different way of moving it.

Good responses in here, I appreciate all the guidance. I ask a lot of questions but it's really only because I am super eager to learn as much as I can. The second model that brunson posted seems simple to me and helped me understand visually the concept of a sump tank.

Fingerlings/yabbies can be kept in the sump tank also? Why would you do that when you have a FT?

Well, for a lot of speicies of fish which are used in AP, small fingerlings look very appitising. So if you like to stock fingerlings at the same time as a couple of bigger fish, it is better so separete them. The fingerlings may very well be eaten otherwise.

Depend of the kind of fish you would like to stock though.

Take care that the pump in the sumptank is not able to "eat" the fingerlings, by putting some type of guard.

I think I can answer your question, Samuel. (BTW, I love your work - highest grossing actor at the box office in history!)
Fingerlings, smaller fish species or crustaceans/molluscs would normally be kept in a separate container to your primary fish tank, mainly to keep them safe from predation. The sump tank is just another body of filtered water that can be utilised, even in just a small way, for the rearing/growing of some useful life forms that may eventually be transferred to the FT when they are large enough.

In a CHIFT PIST system the fishtank maintains a constant volume of water, which is something fish prefer, crawdads(yabbies) don't care so much about water level, which is why they can do well in a sump tank. They are also fond of eating fish, so mixing them with the fish isn't the best idea (and the fish that are too big for them to eat will usually eat them)

One consideration is what sort of site you are building on.

On a sloping side you would naturally use a sump at the bottom and have the fish tank at the top to flow into the grow beds on the second level and inturn they would flow to the sump on the third level and then pumped back to the fish tank.

On hard ground like some of mine which is straight clay you may not be able to set a sump or fish tank in the ground. You would then use a fish tank lower than your grow beds so they can flow straight to the fish tank which then pumps back to the grow beds.

Both systems using gravity and one pump, just positioned at different ends of your system.

Your site will determine what system you use, so that is the first part to consider for your system design.

Keep asking and remember "The only stupid question is the one not asked"

My two bigger systems are standard chift pist systems with 1000L sumps and I am happy with them.
The system in the greenhouse is like Samuel is talking about with a 500L fish tank partially buried and has 7 gb's totaling 900L of constant flood attatched. So a small low wattage pump in the fish tank is all that is needed here, and the fish tank level doesnt change with CF. Very simple system but it works great.

There are many ways to put a system together as can be seen in all the members system threads, so just choose what suits you and your situation

What are the pros/cons of keeping crustaceans in the sump tank? Do they produce a lot of waste compared to fish?

Depends what type of crustacean your talking about. If its yabbie or marron I can only offer this :-

Pros = your fish cant eat them, they cant eat your fish.

Cons = cant think of any.

In regards to waste production, they eat a lot less so they produce less waste compared to fish.

thanks Charlie. do you mind listing off the most popular crustaceans used in aquaponics? Also the most tasty?

Guys I am very new to Aquaponic's and I am still unsure exactly how the sump works. My Understanding is when the water in your Fish Tank gets to a certain level the float switch turns the pump on which pumps the water from the Fish Tank and floods your grow beds. The water then drains down into the sump and once the water in the sump gets to a certain level the float switch in the sump turns the pump on which pumps the water back up in the fish tank.

What I don't understand is if the sump is to keep the water in the Fish tank at a constant level does this mean that there is water constantly being pumped through the system?

If you are running your system like that you don't need a sump. I have a lot of grow beds, they are gravity fed from my fish tank, they in turn siphon into my sump, where the pump pumps the water back into my fishtank. Have you read through the IBC of Aquaponics yet? It is a free download, loaded with the best info on Aquaponics out there. After reading it I had relatively few questions, and was able to design my system.

The kind of system you are describing with multiple pumps and float switches has been done but is generally not preferred (because float switches and multiple pumps that need to be controlled by those float switches or things could over flow or get pumped dry, mean extra failure points)unless your layout is such that you can't do a one pump constant height in fish tank sort of system or a simple system where the grow beds simply drain back to the fish tank.

Anyway, your question "does this mean that there is water constantly being pumped through the system?"
Answer, that depends, is it a constantly pumped system with siphons to drain the grow beds? or is it a timed flood and drain system? In timed flood and drain there may be periods of time where very little water is flowing (just a small trickle from the grow beds to the sump before the timer turns the main pump back on.) But if it is a constant flow system of any sort then the main pump would be moving water around the system constantly and the sump pump would be turning on intermittently as the flow switch dictates.

I suggest you look up CHIFT PIST and CHOP to get some ideas of how to lay out a system without needing to worry about second pumps and float switches though.
Here is a thread that might be helpful to you
http://www.backyardaquaponics.com/forum/viewtopic.php?f=11&t=5311

Ronmaggi, you say your pump only uses 100 watts. Is it an AC or DC pump? I am trying to to find a low amperage dc pump to get my system off the grid. Right now I have a 145 watt PV system from harbor freight and 70 AH of batteries but the cheap Harbor freight DC pump uses 5 amps so the math doesn't quite add up. Does anyone know of a low wattage/amperage DC pump? I don't need the 1000 GPH that my pump says it puts out.

This is the one I have, not sure of the Amperage though. Seems to be a good pump have not had any issues with it yet. I am now using it as a backup for power outages but eventually 3 or 4 of these will run my entire system.

http://store.waterpumpsupply.com/mppufrse316s8.html