Large systems on Timed Flow

[Kobus Jooste]

Hi all

 

I am currently re-visiting a commercial system dsesign and costing that I did a few years ago.  I am not all that happy with the energy requirements of the system.  As far as I understand, most large systems are based on permanent flow (water pumps and air pumps in the rafts).  I am looking for examples of large systems that can still function on timed flooding of media beds.  I am looking to turn my original HD design into a LD koi system with multiple tanks, gravel beds and rafts.  The rafts will need some aeration, potentially the fish tanks too, but I am trying to scale back on the "allways on" part of the design as much as possible (The original HD design was based on the UVI component ratios and uses 2 kW per hour).  I have not downloaded the larger designs from the Friendlies, thus if they cover something in this range I'll be willing to download the plants to see how similar they are to my concept.  I have the Backyard IBC pdf and have already seen some pretty large systems in there.

 

If anyone else knows of other community-scale systems that are designed around low power consumption I'll be quite interested to learn. 

[RupertofOZ]

Sounds a bit like a "flout" Chris....

 

TCL has already done some work with our aquaponics valves that allows them to be used and sequenced by gravity feed from a constant flow system....

Chris Smith said:

My commercial system has 640 sqft of trough space and 100 sqft of media beds. My FT has a constant overflow to the media beds. There are 4 media beds and I am developing special valves to direct the water flow to each bed for 15 minutes each. I use a 50w water pump and have two 40w air pumps.

The valves that I am developing work on flow and no pressure which will enable a constant flow system to provide a timed flow to media beds. Each bed has two valves. When the flood valve opens the drain valve closes. When the flood valve closes the drain valve opens allowing the bed to drain very quickly and not tie up excess system water from the sump.

[TCLynx]

Actually, Chris's valves sound like they might be just the ticket to controlling the flow to a gravity modified aquaponics indexing valve if they work well. 

I had trouble with my low pressure automated valve regularly and when a bug got fried in the electronic controls I haven't managed to replace the electronics.

 

Hence why the big system is pumperflouternating now.

I think I could get the FLOUT to drive the indexing valve but I don't have enough height between the water level in my fish tank and the surface of my grow beds to make that one quite work.  Lots of flow balancing issues to get the flout to work for this purpose too.

 

[RupertofOZ]

I'm certainly intriqued Chris... especially as to how  you "time" and sequence the flow....any more detail....

[Chris Smith]

I'm not sure what a flout is. I am working on several completely different designs to preform the same function. I am trying my best to use off the shelf items to create the valves to keep the price affordable.

RupertofOZ said:

Sounds a bit like a "flout" Chris....

 

TCL has already done some work with our aquaponics valves that allows them to be used and sequenced by gravity feed from a constant flow system....

Chris Smith said:

My commercial system has 640 sqft of trough space and 100 sqft of media beds. My FT has a constant overflow to the media beds. There are 4 media beds and I am developing special valves to direct the water flow to each bed for 15 minutes each. I use a 50w water pump and have two 40w air pumps.

The valves that I am developing work on flow and no pressure which will enable a constant flow system to provide a timed flow to media beds. Each bed has two valves. When the flood valve opens the drain valve closes. When the flood valve closes the drain valve opens allowing the bed to drain very quickly and not tie up excess system water from the sump.

[Kobus Jooste]

Thanks everyone for their feedback.  Chris, I'm especially interested in the makes or types of the air pumps too, as I have locally sourced small air pumps of that energy consumption range but do not see them delivering the type of air stone activity that the raft area you mention will require.  I also have a 70 W vortex blower that I bought for the research system but it too is a bit on the feeble side with air stones.  I have found that siliconing 20 mm pvc pipe to the base of a tank and drilling small holes into it works better than air stones with the small blower.  If I remember correctly, you stated that you have 3 "soaker hoses" per raft?

 

I sure hope this opportunity comes off because I am more into community projects than the big commercial units that we looked at before.  Thanks again for all of those that have contributed so far.

[Chris Smith]

Kobus, the three soaker hose system is a friends here on the Big Island. He uses a blower. The air needs several PSI just to get through the hose. I do not think this is the most efficient use of power.

I use Pondmaster AP 40 air pumps. I have the pumps manifolded together and a 3/4 valve going to the troughs. I have to throttle back the flow to the troughs as it is easier for the air to escape in shallower troughs than the deep FT. I run a 3/4 mainline down each trough. Off the mainline I run a 1/4 drip irrigation hose with a mini valve in line before the air stone. My troughs vary in depth and I have to tune each air stone so that I get an even flow rate. Stones are every 4 feet. I provide the FT with just enough air to keep the poop turning over and not collecting on the bottom.

[Francois Lemmer]

with my pilot project i kept things simple and cheap

i used a .75 kw pool pump pumping in cycles controled with the water level switching pump on and off and a air pump 24/7.

my electricity was minimum...250 kw per month +-8 kw per day+- 0.3 kw per hour

 

[Kobus Jooste]

Thanks Chris.  Do you operate a SLO on the fish tank? I set up a circular flow pattern in my research unit fish tank (2500 liter circular) with a water pump (actually, with a tapped off part of the return flow coming from the main 45 Watt unit) and a bottom drain, which allows me to collect all the solids without any other means of activity.  I have a closed-up stand pipe coming off the bottom drain that I can open up in case there is any muck on the surface of the tank that I want to suck off but that is hardly ever required.  It has been going for about a year and I just serviced the pump for the first time this week.

Chris Smith said:

Kobus, the three soaker hose system is a friends here on the Big Island. He uses a blower. The air needs several PSI just to get through the hose. I do not think this is the most efficient use of power.

I use Pondmaster AP 40 air pumps. I have the pumps manifolded together and a 3/4 valve going to the troughs. I have to throttle back the flow to the troughs as it is easier for the air to escape in shallower troughs than the deep FT. I run a 3/4 mainline down each trough. Off the mainline I run a 1/4 drip irrigation hose with a mini valve in line before the air stone. My troughs vary in depth and I have to tune each air stone so that I get an even flow rate. Stones are every 4 feet. I provide the FT with just enough air to keep the poop turning over and not collecting on the bottom.

[Kobus Jooste]

Thanks for the input Francios.  I cannot guage scale from your pic though.  The commercial design I have is for a total of 130 m2 plant grow space and 4 fish tanks identical in volume and fish stocking density to the UVI system - around 14 000 liters with high density stocking.

Francois Lemmer said:

with my pilot project i kept things simple and cheap

i used a .75 kw pool pump pumping in cycles controled with the water level switching pump on and off and a air pump 24/7.

my electricity was minimum...250 kw per month +-8 kw per day+- 0.3 kw per hour

 

[Francois Lemmer]

14 000 litres per dam....

how much water in the system ?

 

this system had a footprint of 120 sq.meters and a total of 12 000 l water

[Kobus Jooste]

Francios - it was 14 - 16 000 liters in total for the fish tanks (not per tank), with quite a large sump.  The entire water volume was 60 000 liters with approximately 125 m2 plant space. I do not believe in any size fish tank where I cannot reach the centre point of it from the side - my 2500 liter research tank is just about as much as I like to have (a little too large actually)

Francois Lemmer said:

14 000 litres per dam....

how much water in the system ?

 

this system had a footprint of 120 sq.meters and a total of 12 000 l water

[Frank De Block-Burij (hygicell)]

you should all try and calculate the energy efficiency of your pumps:

I have done so on a regular basis and found that all pumps bar none (found so far) are a shame

that is the result of poor design: all of these (centrifugal) pumps are designed for heads of about 30 m which is far higher than we need (1-2 m)

just take one look at the impeller of your pump and you will see at first sight that the most simple fluid dynamics are ignored

the formula is simple:

pump effect (in kW) = head (in bar) x volume (in l/min) / 600

pump efficiency (in %)  = pump effect (kW) / energy consumption (kW)

the results are deplorable: often much less than 3 %

(so if you find a pump with an efficiency of over 5 % make sure you let me and everybody else know)

imagine having a pump with an efficiency of 30 %: that would mean a 10 fold reduction of energy consumption

the solar panel system you need now would be able to drive 10 pumps !

air stones are also an illusion: as bubbles only become efficient at aeration if injected at over 7 m depth

the only result at aeration is obtained by the movement of the water, thus exposing it to air, where gas (oxygen) exchange is natural and automatic up to the saturation point

for low heads, the most efficient pump is TMO a propeller pump

you can buy all kind of propellers and motors from model boat stores

I really should start experimenting with the parts that have been lying around here for months now

Frank