Backyard Aquaponics
A place to discuss aquaponics

This might be a stupid question but I was wondering for those who have a sump in their system (at the lowest point) and are pumping from there to the highest point. I assume they must have some sort of drain from the fish tank.

My question is how do you drain the solids from the fish tank without the ability to pump the water out from the bottom of the tank?

Do I have this all wrong, I was thinking about adding a sump and marron maybe during my next fish change...

Please bare with me

Usually via a SLO (solids lifting overflow) in the fish tank to the bed/s.

Often, systems that incorporate a sump do so because the level of the GBs is lower than the FT and the water exiting the GBs needs somewhere to flow to (or accumulate, in the case of F&D) before being pumped back to the FT. In these systems, water is typically removed from the FT courtesy of gravity, using siphons or Solids Lifting Overflow (SLO) pipes. If these are carefully designed and positioned then solids can be drawn out of the bottom of the tank by utilising the 'suction' of these devices, and then distributed to the GBs.
Hence, to answer your question, solids are drained from the bottom of the tank without the need to actually pump them out.

I run a sump that isn't the lowest point in my system- its high and low water levels are lower and higher respectively, than the top and bottom of the FT.
The flow is: FT > SLO > ST > Pump to GB > gravity flow back to FT

As everyone has mentioned already you would use a SLO.

Some pipe across the bottom of your tank with some holes drilled or slots cut:



It then travels up the side of the tank (either internally or externally) and sets the height of the water. A T piece is used to prevent it from becoming a siphon.





They draw water from the bottom of the tank which also sucks up the solids (hence the name).

They can either deliver water from the fish tank to the growbeds or (as is the case with Gunagulla's system) from the fish tank to the sump.

thanks guys, this info is brilliant.

So if you are going to make use of a sump purely to keep Marron or small fish in, is it preferable to have the fish tank draining into the growbeds (keep them lower than the fish tank) as apposed to having solids draining into the sump making the sump tank dirtier...

At the moment my growbeds will be highest, then fish tank and sump will be the lowest point.

thanks again
Lloyd

Absolutely.... and there's no point in designing a system.. that sends the solids/wastes back to the fish tank...

Arbe,

On your last picture, whats the small white hole fitting on the side of the tank about, next to the SLO pipe?

thanks

The was there when I purchased the tank (second hand). I turned it into an emergency over flow (although it doesn't get used).

ok so in this example I have drawn up, although the dirty water isn't going into the main fishtank it is going into the sump before being pumped, is it better to lower the growbeds? (easy for me to do I just need to shorten the stand legs...

I was also considering dropping in a radial flow filter

ah ok, so can I ask what type of fitting you have used in the side of the tank to form the water type seal to pass the 90mm pipe through? sorry to be a pain

The fitting for the pipe through the tank wall... is a "uniseal" ... a rubber gasket/grommet...

Uniseals. But if you are looking at 90-100mm, then something called a rapidseal is half the price. (sorry paul).

Dropping your GB would be a good idea, let gravity take the solids to the bed, pumping the solids can smash them up and have slightly less chance of being caught in the bed - most people would suggest against sending fishpoo to your sump.

Yes better to go the standard chift pist method, that way your solids are lifted gently out of the fish tank with the water flow, especially if you are putting a RF filter in there. You don't want your solids chopped into little pieces by the pump, your filter would be far less effective then.

That's the basic layout of my system, except my sump is a bit higher and half the depth of the GB- both ST and FT are almost completely buried, for thermo-regulation.

I have my GBs at a convenient height for doing stuff with plants, I wouldn't want to lower them so I have to bend over to work on them.

Re Yavimaya's new post- The water returning to the FT from my GBs seems very clear, without suspended poo, so I think the GBs are doing a good job of catching it all, even if it is minced up a little by the pump.
I would think having smaller particles allows it to be more evenly distributed in the GBs, larger bits of poo would tend to clog up the gravel close to the GB inflow, IMHO.