Backyard Aquaponics
A place to discuss aquaponics

I am going to use an overflow in the fish tank that will go to the sump and the growbeds will also drain to the sum. One pump will run continuously and split between the grow beds and fish tank.

My question is, can i just have a drain at the top of the fish tank as an overflow and no drain in the bottom? or is the bottom drain critical to removing solids? I am using 40mm wastes (normally for a sink) and wonder how effective this would be at removing solids even if it was at the bottom.

One overflow at the top sure saves a lot of plumbing and there is no pump or anything else inside the tank. Bonus is the tank can never be pumped dry.

Your thoughts would be appreciated.

Tez

How big was your tank? 1000 litre would be about the maximum for a non bottom drain.

Tanks are 500ltr (Bunnings cheapies) each and i was going to have 2 in this system.

Top overflow will be no worries, especially if you have a decent amount of fish. They seem to stir it up quite well.

A 500 litre tanks does not leave much room for a lot of plumbing internally.

If you dont have many fish, give it a stir weekly to stop any builup on the bottom.

There are a couple ways to do constant height in fish tank while still sucking solids off the bottom. If you don't wish to plumb thought the bottom of the tank, that is not a problem.



I would recommend having the pump feed the fish tank only and the fish tank overflow into the grow beds only. This way you help keep more of the solids out of the sump, thereby keeping the environment for the pump cleaner and making maintenance easier.

I use the tee going to the bottom, like at the bottom of the picture. Works great and the hole is still at the top where the water pressure is lightest for less chance of nasty leaks.

In my IBC's I have used both a top overflow, and the 'T' style sucking from the bottom type. There is no difference.

I cant gravity feed to grow bed. I plan to build growbeds over the sum tanks.





The two baths are connected by the botom wastes. I could run 2 pumps and pump to growbeds from the bath with the FT water coming in and to the FT from the other. This should reduce the amount of solids being pumped back to the FT.

Any other bright ideas APers?

Why? Do you mean by "bottom drain" a hole in the bottom or just that the overflow water gets taken from the bottom

Once the tank gets bigger than around 1000l, the normal circulation of water does not allow all of the solids to simply overflow out the top of the tank.

A bottom pickup would then be required to keep the water clarity good. Either a hole in the bottom of the tank, or the prefered style as per TCL's drawings.

TMO you always need some kind of system to remove the solids from the bottom, whatever the size of the tank.
But there are many ways to do this
see the drawings on the thread: What to rename the "venturi drain" to
viewtopic.php?f=8&t=4127&st=0&sk=t&sd=a&hilit=poo+sucker&start=15

if you would wish to recirculate part of the water directly from the fish tank to the sump and back, you could introduce in this line a settling tank for solids removal just before the sump that overflows it's top water into the sump. A second overflow that goes to the bottom of this settling tank will allow you to drain the solids every few days.

Frank

Well obviously frank is operating a 1000 litre tank system, that magically needs a bottom pickup. Must be something wrong with mine

are you seriously trying to tell me that NO solids are settling in a 500 liter tank, Ozzie?
I have seen solids settling in aquariums

the only way to avoid this with a system that doesn't take it's outflow water from the bottom is by over sizing the pump so that solids stay in suspension and are eventually carried outside

that is not the most efficient way nor the fastest nor the healthiest for the fish
the fastest and most efficient way is to keep the solids on the bottom and continuously pick them off there

frank

The fish in the IBC (1000l) do an excellent job of keeping the bottom of the tank spotlessly clean. Nothing settles on the bottom. Water is crystal clear.

25mm pump line in the top of the tank, 2 x 25mm lines out, from the top of the tank.

Nothing special, just the fish stirring the water up.

Yep, with fish like trout or even catfish, they do seem to keep the bottom dusted off quite well. But if you are relying on flow to get the solids off the bottom in a tank with only tiny fish, you need some sort of drain or mechanism that will help you out.