Very Low watt pump

[GaryD]

Hi gavinl,

I've encountered a few people who switch their pumps off overnight.

If you're relying on the water returning to your system to aerate your fish tank, it wouldn't be a good idea. I'd recommend that you have a small air pump hooked into your system anyway......it's cheap insurance.

Cutting back the pumping cycle during the night.....particularly in cool weather......will help reduce the heat loss in your fish tank.

In warmer weather, it might pay to set your pumping cycle up to water once or twice during the night. If you're using the electric timers with the 15 minute tabs, this will be easy to set up.

Remember, that it's not just the plants that you're feeding in a gravel grow bed......it's the beneficial bacteria, too. When your pump is switched off, you're not converting the ammonia and nitrites in the water.

Gary

[fishfood]

Hi again :)

I was just wondering if it is necessary to run the pump at night in a flood and drain system.

At the moment I have the following figures for my proposed system:

Fish tank: 1500l
Grow beds x 3 = 2826l
Ratio = 1 : 1.88
Pump: Rio Hyperflow 17H (45watts per hour at 1m head)
Energy needed to flood: 30.75 watts per Hour (41 min) or 738 watts per Day
System: Flood and Drain (into fish tank)

This system although quite energy efficient would still be the the third biggest power drain in my house - first in the fridge/freezer and second my house water pump.

If I could use it in daylight only or at least for 16 hours rather than 24,it would make a huge difference and even allow for a larger system.

All advice appreciated

gav :)
Over winter my pump turns of 4.30 in the evening and on 8.30 in the morning
yes i run an air pump

[sillyoldfart]

At the moment I have the following figures for my proposed system:

Fish tank: 1500l
Grow beds x 3 = 2826l
Ratio = 1 : 1.88

Hi Gavinl. You say you will be using 3 growbeds, total cpacity of 2826ltr.

I make that about 950ltr per growbed. What are you using. How much did they cost?

Could you post some pictures or links?

[Murray]

I switch my pump off at around 4:30 pm every day and back on at about 9:30 am. Have an air pump in the tank to make sure of aeration. Works well for the winter.
Water is very clear and clean.

[gavinl]

Hi Silly

At the moment I am just at the planning stage mate - nothing has been bought or decided upon.

My figures are based on Joel Malcolm's 2m x 0.30m corrugated iron grow bed tanks which he uses for grow beds. If posible I would like to do something similar as I really like the look of the iron - will have to get quotes soon though.

My major worry is cleaning up the stuff on the bottom, as he uses gravity/suction for his tanks, but I would like to bury my fish tank to save on the costs of stands. I suppose a pool cleaner might work, but power is also a consideration. In order to save more energy (lower the head) and dig less, I would be looking at a tank of 2.5m x 0.6m (leaving 10cm empty of water on the top), whereas his was 2m x 0.90.

Unfortunately, my last calculations for the Rio Hyperflow were wrong as they were based on 30cm head, whereas I'm trying pretty hard to make it a minimum of 90cm head.

gav

[gavinl]

Hi again

I am trying to lower energy by decreasing the head and was wondering if there is a problem with only having a fish tank height of only 30cm of water.

I think I would normally have the fish tank water height at 40cm (for 4 grow beds), but if I would only like to grew 3 rather than four beds, a water level of 30cm would make for a better ratio at 30cm. At the moment, I'm just trying to make the proposed system as flexible as possible ie changing water levels to increase/decrease grow bed numbers. Please let me know if you reckon I'm off on the wrong track.:)


As size is not a huge problem (live on 5 acres) but energy is (solar house), I could decrease the height of the fish tank to 0.50m by increasing the diametre to 2.8m and get roughly the same volume - although my maths is pretty rough.:) This plus the 30cm grow bed height would make for a 0.80m-0.90m head in total. I can get the energy output for the Rio Hyperflow at 0 head, 30cm head and 1.2m head and there is a lot of difference in losses for each stage. If anyone has the figure for 80 or 90 cm head that would be great - it doesn't seeem to be a set ratio.

Additionally, I was wondering why it is okay to turn the pumps off in winter at night but not in summer.

As usual, any advice would be greatl;y appreciated.

gav:)

[GaryD]

Hi GavinL,

If pumping head height is an issue, why don't you simply position your pump at a greater height within your tank.

I'd rather see you use a 900mm deep tank and stand the pump on a plastic crate (so that you're pumping with a head height of 450) than attempt to keep fish in a tank 450mm deep.

For energy consumption purposes the effect is the same, but it's a better environment for your fish.

In winter, your grow beds will dry out slower than in summer. That's why you can cut back on your pumping regime in winter. For your purposes, a greater summer energy consumption is offset by greater solar power generation.

Gary

[gavinl]

Thanks Gary.

Sounds good mate and a lot less hassle.

gav

[GaryD]

GavinL,

I've just taken a look the box my RIO 17HF came in and at:

0 head it pumps 4500lpm
300mm it pumps 4140lpm
1200mm it pumps3190lpmTaking an educated guess, I'd suggest that it's probably going to shift 3500 - 3600lpm at 800 - 900mm height.

Gary

[njh]

Hi GavinL,

If pumping head height is an issue, why don't you simply position your pump at a greater height within your tank.

I'd rather see you use a 900mm deep tank and stand the pump on a plastic crate (so that you're pumping with a head height of 450) than attempt to keep fish in a tank 450mm deep.
Gary

It doesn't work that way. Read about hydrostatic pressure, then go and implement an axial flow pump (why don't people listen? Why do societies fail when their scientists already understand the reasons for failure?).

[gavinl]

Hi njh

It sounds very interesting for my situation. Could you fill me in a bit more or point me in the right direction to start looking into it.

Thanks

gav

[Murray]

The theory is great, but in practice........The only trouble is axial flow pumps are not readily avbl, especially at the bottom end of the market.
The long and the short of it is, if you are going to do aquaponics you will have to go out and buy the best pump you can find locally and be prepared to pay for some power.:)

It is easy to get all hung up on trying to work out all sorts of fancy schemes and 2 years later there is still not a single tomato to show for it.

I believe, it is better just to start.....with what gear you can easily get your hands on. Give it a go.

I know some will not agree, that's fine....

[gavinl]

Looks like I'll plan on getting the deeper fish tank and try to put the pump closer to the surface to lower the head. Thanks for the info on summer/winter pumoing. I'm up in North Qld, so it definitely is warm in summer.

Thanks all for the help

gav

PS: Gary, I also looked at the Rio Hyperflow 20HF and if my calcualations are correct (a big if) it looks a little more efficient. Who knows in real life applications though.

[GaryD]

Hi njh,


(why don't people listen? Why do societies fail when their scientists already understand the reasons for failure?).

Probably because people remember that some of the world's most pressing problems are, in fact, caused by scientists.....present company excluded.

Examples include nuclear power and weapons, those who have sold their souls to the agri-business and petroleum giants and those who advise the Prime Minister on issues like global warming and other pressing social issues.

Gary

[njh]

Hi njh

It sounds very interesting for my situation. Could you fill me in a bit more or point me in the right direction to start looking into it.
gav

Of course it depends on whether you want something off the self, or if you are interested in optimal performance.

My first effort would be to get a drill mounted paint stirrer and some suitable diameter PVC pipe. You might glue or weld on some longer blades to allow for slower rotation. Above the vanes you would have a 90 degree corner with the drive shaft coming out the top and water going off to the beds.

Alternatively, you can buy toy submarines that run on battery power, find one of them and attach the propellor to a suitable shaft with the same pipe arrangement.

By putting the drive shaft and motor above the vanes, and through an elbow you avoid the need for a robust waterproof bearing or motor.

If you want something off the shelf, I can't help you. The first to market advantage, combined with the slightly different head and flow requirements of most people's water features means that there are no low power axial pumps on the domestic market. But if you wanted off the shelf you wouldn't be using solar power either, so you're clearly someone with l'espirit de engineering.

More blades and wider blades mean slower rotation, but also lower maximum flow.

When you've got it working, write it up in renew or something.

(For those who don't yet understand the energy involved in pumping, consider that most people can output about 100W whilst riding a bike - a 600W pump for 10 minutes each hour would require a person pedaling a bike all day long to be replaced.)

[gavinl]

Thanks for the explanation njh

Unfortunately, it sems a bit beyond my skills - perhaps after my system is up and running, I'll do a bit of experimenting.

All the best

gav

[gavinl]

Hi Gary and Murray:)

Just wondering what the difference is between an automatic and manual pump on your website.

Thanks

gav

[GaryD]

Hi Gavin,

An automatic pump has a float switch on the pump......a manual one doesn't.

Gary

[greenman]

So im about to start myself and trying to figure out which pump i want. Im going to use a continous pump system and some auto siphons. I tried to do some basic math and I may have screwed it up. But from the looks of this it looks that you pump about 32% of your total fish tanks volume every hour. Does that sound accurate?



Hi Gav,
I use two pumps.
From the fish tank to the grow beds is a 240 volt x 700 watt x 15,000 ltrs per hour pump. It only runs once every 40 to 45 minutes and then the actual run time is 3 to 4 minutes. So the actual watts used is very small.
The other pump that moves the water from the collection sump back to the fish tank is 240 volt x 300 watt. It runs about every 5 - 7 minutes or so for about 3 minutes. That is, 5 to 7 minutes off then 3 minutes on.
My pumps are controled by float switches.
So, once again the actual watts used is really low.

I have a 2300 ltr tank with 4 x 585 ltr grow beds and one 250 ltr grow bed.
I also run another smaller pump on a seperate smaller system which is a 90 watt pump x 4000 ltrs per hour. I run that pump continuously....don't really need to.
Murray

[Murray]

Hi Greenman,
Everything changes...we are learning all the time. All of our new systems operate on continuous flow and auto siphons. This allows the use of much smaller pumps.
The configuration is also a lot more reliable. There is no need to have float switches and timers and the like.

As an example of a mid sized domestic system.

1250 ltr tank with a 400 ltr sump we use a 3000 lph pump which is effectively about 2000 lph taking into account the efficiency loss due to pipe and head etc.

So the total turn over of water is approx once per hour. The pump draws 40 watts according to the label on it, but the watt meter reads 28 watts draw. So the power consumption is about as low as you can get.

It works very well.

[GaryD]

Hi Greenman,

I also use Murray's auto-syphons (seven of them) and they work superbly.

Prior to switching to auto-syphons I had used float switches and timers and I spent far too much time adjusting the rate of flow to avoid flooding my grow beds.....while, at other times, the level in the grow beds would be less than it should have been due to lower fish tank levels, microfilm build up, etc.

The autosyphons have cured all of that. My grow beds now flood to a pre-determined level every time. On the rare occasion that they don't function (usually because I don't have adequate flow through them), they default to a failsafe position because the grow beds will be full.....so the plants are never without water.

Gary

[ElfNori]

My first effort would be to get a drill mounted paint stirrer and some suitable diameter PVC pipe. You might glue or weld on some longer blades to allow for slower rotation. Above the vanes you would have a 90 degree corner with the drive shaft coming out the top and water going off to the beds.

What an exceptionally clever idea! I've been using a vacuum hose (bear in mind, I don't have an AP system running yet, I'm still dealing with lots of big goldies and trying to keep them healthy) to clean the bottom of my tanks. I drop it in the tank, hold my hand over one end to hold the water in until I can drop it to the ground outside the tank. Then I wave the other end around the bottom and siphon all the junk out.

Your tricky business is a much easier way to go! I HAVE to try this! I'll build a 2" pvc wand with a wire mesh bulb on the business end and suck that stuff up and out!