Backyard Aquaponics
A place to discuss aquaponics

I am going to go for blonde here TCL ....

Am I right in understanding that to do this you have your GB's lower so fish water drains directly into them by gravity..... (Question 1: can this be done in a way so flood and drain is effected?.... and Question 2: How much lower?)...... then all GB's are drained into a big tank.... I assume that is what a sump is.... this girl is still tanslating the lingo..... from there it is pumped back to fish..... (but I would like to do it via an elevated tank so drops from a height to increase DO.) Then somewhere you put a venturi drain to process the solids at the bottom.... that is of course when you actually understand what a venturi drain is.... Ha!

HOWZAT?!

Pretty good.

We normally call it CHIFT PIST (Constant Height in Fish Tank - Pump in Sump Tank).

A lot of the aeration occurs whent he beds drain to the sump - remember this water is then being pumped to the fish tank - where you can create further aeration by it going through a venturi or just dropping to the tank. The venturi drain can be modelled in a couple of ways, but the one that is quite popular is to have the water flowing over the top of a standpipe and out the drain (hence the constant height) but forcing the water to come from the bottom of the tank (along with crap) by having another pipe ouside of the drain standpipe - with this outer pipe being higher than the water level and having crenelations cut out of the bottom. Therefore water has to come through the crenelations at the bottom, before travelling upwards between the 2 pipes and then over the top of the inner pipe. Simple hey

Here are a couple diagrams of possible ways to do venturi drains.


1-yes you can still do flood and drain with your grow beds.

2-Only enough lower so you can run plumbing to the grow bed without causing any air locks in the pipes. I would say the top of a bed right next to a tank might only needs to be 3-6 centimeters lower than the high water level. Probably the size of the plumbing used. Be sure to use large plumbing for a venturi drain on a large system since you want solids to flow quickly.

As to where the grow beds would drain to, yes the sump tank. (good points about having the water go through grow beds before going to the sump tank is that the sump tank will stay cleaner.) The sump tank needs to be enough lower than the grow beds so that they can drain properly. This will depend on your method of flooding/draining. I believe timer/slow drain could work as could continuous run and auto siphons. (The height of the beds above the sump is more critical with auto siphons than slow drain The more the water has to fall, the faster the beds will drain.) Sump needs to be sized to hold all the water from the grow beds plus some extra so the pump doesn't run dry and the sump doesn't overflow.

The pump pumps water out of the sump and into the fish tank. You can achieve plenty of aeration provided the pump has enough flow and power to give you more than a trickle. You can also use the flow from the pump into the fish tank to get the water in the fish tank circulating and help move solids to the drain. Like in a round tank, a bit of circular flow often collects solids in the center so it would be good to have the drain intake at the center.

Hope this helps a bit.

OK......

I get the need for 2 pipes. The outer pipe must be higher than water level so that the only way in is below where the gaps let water in dragging solids along with. The inner pipe... the stand pipe..... must be below water level... (Question: how much lower? Does it matter?) thus guiding the water and solids quickly down the drain - the pipe being large enough in a large system not to clog because of ease and speed of the moving water. This then moves from underneath the fish tank..... (watch this space! got bedrock to deal with on the planned site!..... ) in a U shape to the growbeds which are positioned just a little lower than the HIGH water level (that I am going to enjoy establishing with all this flooding and draining! LOL.... this simple little idea of aquaponics appealed to me because I could put it all so EASILY under Greenhouse cover and stop the monkeys enjoying my salads!!!!! )

The GB's then drain with an adjustable valve to the sump. I thought putting a valve gate in would help with getting the right flood and drain rates established. The sump should be positioned lower than the GB's to ensure complete drainage.

I haven't a clue what an auto-siphon is.....

The volume of the sump must be bigger than the volume of all the GB's flowing into it to prevent overflow.

Why can't a pump run dry in between? Must it run continuously... (Sorry! The more my questions are answered the more I have!!!!)

The pump must best be large for best aeration cos a small pump that gives a trickle does not give much DO to the fish tank. Return of water to the tank should be placed where a flow can be created that will circulate the solids to the lowest point. A circular tank is best with the venturi drain smack in the middle and sides sloping down to it.

Sorry for all the repeat back to you.... helped me see what I did and didn't understand. Hope I did understand!

Set the height of the inner standpipe to the maximum height you want the water in the fish tank to be Cyara....

Sorry.... also forgot to ask.... How would you create flood and drain with this system? Would a venturi drain not continuously drain the fish tank?

BTW thank you so much for all your trouble TCL ... and to VB!.... Much appreciated. I have been bitten by the AP bug and realise how much there really is to learn! I cannot imagine having learned so much in such a short time without this forum. It is absolutely wonderful. Hope soon I can help others as much as I am being helped.

O I see! Thanks RupertofOZ. That would then effectively create the flood and drain would it not?....cos not always at maximum water level in the fish tank and only when it is will it start draining again.

It essentially just overflows when it reaches the set height.... the outer pipe is just to help suck the solids in, up and into and down the "overflow" standpipe....

As you're pumping from the sump... the water level rises... overflows to the growbeds...

Returns to the sump... which pumps back to the tank... etc....

Thus the Constant Height in Fish Tank.....

If the sump pump fails.... then there's no pumping to the fish tank... hence no "overflow... and no water to the growbeds... therefore no further water to the sump

So as long as the sump is large enough to hold the combined capacity of the growbeds...

It's basically foolproof... and no water is lost...

Growbeds can be flooded and drained with a similar standpipe technique... but most have utilised siphons to initiate a rapid drain... either with simple "loop" siphons...

Or with a "bell" siphon... which is essentially the same as the fish tank arrangement... but with a cap on the outer pipe to initiate the siphon action...

Regardless of the drain method.... the growbeds "flood" to the set level then drain... hence "flood and drain"....

Using siphons just allows for a rapid drain which sucks the oxygen down through the growbed media... great for plant roots.... and adds oxygenation to the return water...

Cyara, here is a collection of pics showing a CHIFT PIST with venturi drain etc

Pic 1 - looking down at sump tank (at ground level)...2 pipes running from pumps in sump up into fish tank (2nd smaller pipe is the 12v backup pump if power fails)
40mm return pipe from GBs - please note black electrical tape and all that other good stuff that makes BYAP such a joy
The water in the sump tank rises and falls as the GBs flood and drain

Pic 2 - far pipes of the fish tank are the inflow from the sump pump, the flow pipe is angled so that it causes the water to flow around the tank...food and poo is then moved to the centre bottom of the tank and removed to the GBs via the venturi drain
The centre pipe is a 50mm pipe inside the 90 mm covering pipe (as per TCL diagram for a venturi drain)...the rectangular cutout seen above the water line is incase of a blockage, the water can then overflow into the top of the 50mm pipe.
The water remains at a constant level at all times in the fish tank independent of whether the pumps are working

Pic 3 - outlet from the fish tank to the GBs...I have 2 rows of 3 GBs, the 50mm pipe is divided and water flows to both rows
The height difference between the fish tank water and the GB height is irrelevant as long as the GB is lower...water in the centre drain pipe will be the height of the GB outlet (on mine there is ~300mm drop)

Finally an overall shot of the rows of GBs and the fish tank to the rear with lots of vegies

Flood and drain in the grow beds can be achieved in a few different ways.

A-Continuously running pump with some sort of fast automatic draining method for the grow beds. Most common being auto siphons-lots of info on the forum about different types of auto siphons. Flouts floating outlets being another method but it takes up more space in a grow bed. Then there are some that use float switches and automated valves or control the pumps with float switches.

B-Timer operated pump that can move enough water to fill the grow beds in a short time and then shut off so the beds will slowly drain until the next timer cycle.

C-There are also methods that use "flush" or "header" tanks to quickly flood grow beds which can then drain by whatever means but those methods are not generally utilized in a CHIFT PIST system.

Do a little reading about auto siphons or bell siphons to decide if you want to do that or if you would rater do a timer.

Overflows are good things to install in grow beds no matter what method you use.

As to dealing with pipes under tanks. You don't have to do round bottom drain cone bottom tanks (unless that is what you already have. Many people may think that is easier but if you are dealing with minimal space for digging, then you have to build stands for them, not so good. There are benefits to rectangular raceways and a venturi drain that is simply a pipe extending to near the bottom of the tank and then plumbed out of the side of the tank at the desired water level with a T to break any possible siphon will work fine too and avoid having to run the plumbing under the tank. I've used both types of venturi drains now and they both seem to work.

Does anyone have a good diagram of a CHIFT PIST system? I like the pics above but am still not completely clear.

Here is a picture of a CHIFT PIST aquarium set up where you can kinda see all the elements in one picture.