Backyard Aquaponics
A place to discuss aquaponics

By hides, I mean things for the fish to hide in. Like large PVC fittings or pieces of PVC. Eariler this season I had one of the tilapia breed in the cage, I had figured this wouldn't be possible with the mesh bottom of the cage but apparently a couple of the fish that were small enough to swim through the 3" pvc fittings managed to breed. Since I removed the "hides" or pvc fittings, there has been no successful breeding in that tank that I know of.

Young tilapia have a huge protein hunger. The fry up through fingerlings can be grown very quickly if you feed them a high protein diet. I have some meal that is like 50% protein that works well for raising the little "stomach's with eyeballs" as I call the fry, if you have them in an aquarium where you can keep an eye on things. Anyway, the smaller fish will definitely eat the even smaller siblings. The trick with the fry is the food they eat has to be very small. they usually eat the microscopic plants and animals that float in the water till they are big enough to eat larger things. Actually, the filter feeding adults eat these things too. The babies will eat algae, actually they seem to eat just about anything they can. A tank full of fingerling (perhaps 1-2 inch tilapia) will happily attempt to eat your finger tips if they enter the water with some food. They will attempt to eat the feed pellets meant for the larger fish even though they can't get them into their mouths and you see all these little fish swimming around with what looks like a basket ball stuck to their mouth.

When I first got my fingerlings, I tested out several types of food. They really liked crumbled up high protein flake food. The high protein meal is really good for the smallest fish. And as the fish get bigger I could then graduate them to the regular pellets. For the fastest growth on tilapia, the smaller fish definitely will do better with good warm temps and high protein food. As the fish get bigger the recommended protein % falls into the nigh 30s. The tilapia actually want more protein than the channel catfish who's recommended % is in the lower 30s. At the moment I've feeding both types of fish on the same pond diet that is 36% protein and I can get it easily in 20lb bags for a reasonable price.

Think I've got it. Electricity sets up magnetic pull on the (metal?) piston... Piston lifts and lets water through. No power. No pull. Piston not held and closes flow by dropping back into position. Water pressure also helps closing action. Called NC valve because needs electric current to open it.... or rests into normal closed position. Hope I have got it .......or I am back on that bicycle...


Yes. I get that.
.... same as with the valve? Normally Closed and Normally Open? Entry C to exit NC is the normal position of the switch. This happens when no water in the tank, and as the tank is filling until the max water height is reached. Solenoid valve... the NC valve.... is connected to the NO exit of the switch.
OK... so solenoid valve... the NC valve.... is connected to NO exit point of the switch. When water rises to the point where switch is activated it flips from the normal position of C to NC over to the other exit point - C to NO to which our NC valve is connected. Electricity flows through this bridge now. Magnetic field is created and piston rises to allow water through.


OK... got it.


What I really meant was: How does the venturi fit in with all this? The venturi kicks in when the max water height is reached.... and the switch kicks in when the max water height is reached.... so how do they work together?


Yes, of course. Power inlets.


When is which used? And why?



Not sure I want timers involved at all. I am most interested in simple mechanics doing the job. If staff need to be trained then maintenance and problem solving is simple. I have heard of timers failing and causing losses.



I would not want to place myself at the mercy of windpower's whimsey. I would use a windmill to generate power to be stored in a battery bank.... as would I do with solar power in the daytime. I would run everything from the batteries. For this reason I would want to keep power use down to the minimum. And if the batteries get too low...... hey! Voila! A bicycle......pedal power can shift that water to the top....


Would the T-type venturi in the fish ponds not be counted as an overflow drain with a gentle siphon action in that it lifts solids from below?


Yes. Must get the solids to the plants. Is why I like the venturi drain. Also want the flouts in the GBs. They exit the water at speed, thus pulling plenty of oxygen into the system.



I will look out for your sketchup drawing.

Thanks again Frank. I have learned a lot. Please correct me if I have misunderstood something. I still have a couple more questions if that is OK

Of course. I should have realised you meant places to hide.



Thanks TCL. Always learning from you...

I want to make my own home-based fish food - alternate to commercial pellets. I need to learn how to mass produce those microscopic animals in the water and look into all forms of protein to feed the fry with I think. Slower growth is OK than that achieved by commercial pellets but I still want to maximise growth before 6 months as much as I can. There must be a way.

Hi Chelle,
congratulations!
pretty amazing!
you are now a graduate with summa cum laude
please tell me where to send your degree

Your summaries are tops. They clearly indicate your thorough understanding.

the remaining questions are mainly connected to your not yet completely understanding the difference between different drain systems and where to use them.

To get off with a good start:
Please stop using the description Venturi in referral to drains

Mr. Giovanni Battista Venturi (1746 - 1822) is getting very restless in his grave every time his name is used in vain
drains (which all work by grace of gravity) are far beneath his level (pun intended)
Mr. Venturi works with pressure drops and mixing media thanks to these pressure drops
gravity helps with that, but Mr. Venturi goes beyond that: if gravity refuses to help... well to hell with gravity: then he will simply create vacuum just for the fun of it
http://en.wikipedia.org/wiki/Giovanni_Battista_Venturi
http://en.wikipedia.org/wiki/Venturi_effect
truly a remarkable man.

now to drains:
on one level there are three basic types of drains:
1. bottom drains. I believe they need little explanation. These will let go a mixture of top and bottom layers of water.
2. overflow drains. These let go only the top layer of water. They will leave all water below the "overflow" level in the tank.
3. siphon drains which let go the bottom or intermediate layer of water. These will normally drain a tank completely if sunk to the bottom or drain it to the intermediate level at which their lowest point is installed.

Then there are combinations of these three basic types.

On another level there are two types of drains:
"continuous" drains
and
"batch" drains.
I hope I use the right vocabulary to make this self explanatory.

In a CHIFT (CHIFT, CHIFT, CHIFT,...) PIST AP system, to keep it simple, you need both types: continuously flowing (as long as there is a supply of water) drains on the fish tank(s):
they will feed the growbeds, filling them more or less slowly
and "batch" drains on these growbeds,
drains that stay closed while the filling takes place and are triggered to open and drain when a certain level is reached in the growbeds.

As you are already familiar with the concept, you might consider these as NC drains. Their rest (=Normal) position is Closed. NC.
When a certain level is reached, they act like a switch that is flipped and open their exit for a more or less fast drain.
when the growbed is emptied, the drain returns to it's "rest" position, which is... yes, NC. Normally (= rest position) Closed.

There are a number of ways to achieve this:
flouts, loop autosiphons, bell autosiphons, float autosiphons ... (not limited to this list)
which all are mechanically or hydraulically activated
but also electrically activated:
the combination of a solenoid valve with one or two level switches (one top level, one bottom level) can form a "batch" drain
so can the combination of a pump with one or two level switches (one top level, one bottom level) form a "batch" drain ... (again not limited to this list).
I hope you understand.

I think the above explanation makes it easy to understand that there is one ground rule for "batch" drains to function properly: the draining must be noticeably faster than the filling. Else the growbed will never empty and the cycle will stall.

... Unless...
unless you can interrupt the filling while the draining takes place
Then draining and filling can be as slow or as fast as you wish.
Electrically activated this is simple and easy: two solenoid valves, one on the filling and one on the draining, and one or two level switches (one top level, one bottom level) that simultaneously close one valve and open the other and vice versa.
Mechanically activated that is more complicated but I believe it can be done.
Combining electrical and mechanical/hydraulical activation gives more options.

Then there is a question of priming: some drains need no priming (i.e. bottom drains), some are self priming (i.e. overflow drains), and some need priming (i.e. over the rim siphon drains).

I believe I have covered it all or just about.

One more thing about flouts: I think they are wonderful
But they have two drawbacks which are:
that they must be installed in the tank or growbed (or in a connected tank or growbed) they are supposed to drain
and that they take up a lot of space.
And don't think that they need no designing: the flout must positively float as long as level is not reached
but it must positively sink at the moment this level is reached.

Unless for high flow (higher than needed in AP) they offer no real advantages
A loop autosiphon will perform just as well.

I don't think that the speed of draining has much effect on aeration of roots or water; it is the ebb and flow that achieves this
faster will be better, but I guess the difference will be almost unnoticeable. Of course I could be wrong.

So with what I know I would opt for loop autosiphons: they are exterior, don't take up growbed space and are easily and visually level adjustable.
Being exterior, maintenance should be easier too (my opinion only, not based on experience).

your remaining questions:
choice of voltage and AC/DC is free to the user

Simply put: for the same power transfer the higher the voltage (= the power differential), the lower the amperage (= the speed of transfer) you must use.
The same cable can transport more power at 24 V than at 12 V, more power at 400 V than at 220 V ...

compare it with transporting air and water though the same tube: in the case of air, more volume will be transported, in the case of water, more mass will be transported.

the main difference between AC and DC is that by alternating the current you can pump even more power through the same section of cable without it heating up.

Consider a boxer: while one uppercut might decide a fight, the incessant consequence of left/right/left/right/left/right is far harder on the opponent and easier on the attacker.

I don't know if these comparisons are scientifically correct, but I hope they explain things.

12/24 VAC are used for backup and solar and cars and trucks, 110, 220 and 400 and 660 VAC are used from the grid.

using a windmill to produce electricity means you are converting mechanical power into electrical power.
That seems to be a good thing since you can stock electricity in batteries for future use.
But when you wish to operate a pump you need to reconvert his electrical power into mechanical power.
All conversions mean efficiency losses. On average far over 30% per step (and I'm being generous).
So wind power to mechanical power = 30% losses (1 kW wind => 0.7 kW mechanical power)
plus mechanical power to electrical power = 30% losses of the remaining 70 % (0.7 kW mechanical power => 0.49 kW electrical power)
plus electrical back to mechanical = 30% losses of the remaining 70 % of the remaining 70 % (0.49 kW electrical power => 0.34 kW mechanical power)
so that means that, in the best of circumstances, you will waste 66% of your original wind power.

Compare this to using the wind to pump water to your header tank:
Wind power to mechanical power = 30% losses (1 kW wind => 0.7 kW mechanical power)
plus...
plus nothing: you have the water where you want it: stocked in the upper tank
You need no pump to bring it there: it is already there.

So you lose only 30% of wind energy compared to 66 % losses.

And you need no generator, no batteries, no complicated regulation circuits and no electrical pump (if you only work on wind energy, else you need an electrical pump). The windmill is your uphill pump.
The upper tank is your battery. Gravity is your downhill pump.
And the wind energy is stocked in the upper tank, ready to use whenever needed.

If your aim is pumping water, generators and batteries are completely redundant. Wind will pump water directly to where you want it: in your battery.
I would rather invest in water filled tank space than in electricity filled batteries, as tanks in an AP system are the most important elements and can be put to lots of uses.


thank you for this wonderful opportunity to explain
every teacher (I don't pretend to be one) deserves a good pupil like you to help him with structuring his material

I truly am enjoying myself, thanks again
so feel free to ask whatever comes to mind.

greetings

Frank

wasn't going to say anything about venturi's, but franks right and it does ring in my ears when i read it

LOL its the small things sometimes, i knew a bloke that would get cut over someone saying "current flow" he'd shout "current IS flow!"

anyway, back to chelle's dream system

I am very interested, so please keep us informed

breeding daphnia is easy:
you need shallow "green" water and a starter batch of daphnia
and patience

Artemia are very convenient: you buy artemia eggs (not cheap) and keep them on the shelf (for years if need be)
when your fish eggs hatch, you pour some of the eggs into salted water, aerate that and within 24 hrs you have tiny artemia larvae just in time to feed to your babies.
you can feed the artemia so they grow bigger as your fry grow bigger

the most difficult is to find the right balance between vegetable and animal protein
a lot of research is done to replace fish oil with vegetable oil

frank

So Frank, Steve, please tell us what these drains should be called? This forum is not the only place I have found them called Venturi Drains.



They are sort of overflow drains since they will only drain the amount of water that gets higher than their overflow but they pull the water from the bottom of the tank without necessarily having to have a hole in the bottom of the tank. And without risk of draining the tank down to the bottom. They are not siphon drains since they require no siphon. So what "SHOULD" we be calling them? I'm happy to call them something else but the larger BYAP group should try to agree on it so as not to perpetuate confusion.

I agree with Frank that if you want to use wind to pump water, use it directly to pump water. You might also desire a separate wind turbine and perhaps solar power for charging batteries for other purposes (like backup air) but since wind can pump directly, do it. Much cheaper, lower tech, less loss. You might even be interested in wind aeration systems but you may not need such things so don't worry too much about that yet.

I agree that loop siphons take less space and are pretty easy but there is a big issue with any type of siphon if you are dealing with a variable flow system. All siphons I've dealt with have a window of flow rate within which they will kick on and off properly. Outside (either faster or slower) than this window of flow rate, too slow and the siphons will keep the beds flooded while slowly trickling over the top or too fast and the siphons never quick shut off and they keep the beds drained down near the low water mark while making sucking sounds. Either of these conditions tends to defeat flood and drain. These are also the conditions which cause such a system to require very large sump tanks since it is possible in say a low flow situation that all the beds in the system could wind up in a full/trickling over state. If the sump were only as big as one level of the cascade, you would have an empty sump quite quickly. Anyway, I would no recommend siphons for a system with a design plan for variable flows. I would definitely recommend FLOUTS or some other mechanism even though they take space.

Flouts are not that difficult to design. I've done it with a sandwich container, a few fittings, some silicone, some flexible pipe, a knife, and some pebbles to adjust the weight so that it floats but will sink when the water starts to flow in. Other people have built home made ones too. There is also a company that makes the engineered large ones like for septic systems and they even have an indexing method for them to sequence many flouts but 3" drains are probably more than needed for a grow bed.

I'll stay out of all the electrical discussions since I'm an audio engineer. I actually think the different flows will work just fine without any of that at all but it is interesting stuff to understand and play with. It might also be handy to have something to trip on the battery backup air system if/when needed (either water flow has been stopped for the night or water flow has stopped due to lack of wind or water.)

what to call them thread HERE
viewtopic.php?f=8&t=4127

FTR i'm not usually pedantic about names of things, but this ones really got the potential to confuse the crap outta a newbie struggling to understand the concept of an actual venturi

Interesting. Yes. The phenomenon of "slippage" experienced in may areas of life... why not here too. Conversion from one state to another does seem unnecessarily wasteful......

One problem. The wind is unreliable. Perhaps a wonderful way of switching to battery power for pumping when the windmill is idle is worth thinking about. One thing we have lots of here is sunshine. Use the sunshine for energy storage. The windmill only pumps water when it is turning. When it is standing still a pump kicks in from battery power. ....

Possible problem. Windmill might not be completely still.... turning slowly... too slowly for adequate pumping. Perhaps a switch could discern something like this and disconnect from windmill to solar battery powered pump in such a case? Just wishful thinking?

yes you would: every restricting of a flow creates the Venturi effect
But it would not serve any purpose: the aim of the Venturi effect is to mix another medium with the one propelled.

true, but at the expense of energy on a location where it serves no purpose (since your aim is not to add another medium)

Suction speed is indeed important to suck up the solids, but the speed is already determined by the pipe diameter.
The margin is very wide as the solids (poop etc...) barely weigh more than water. They will be very close to suspension.

If you would want to siphon up a pebble (it is possible to do so, it is possible to siphon up rocks), then water speed would really matter


indeed it does, but it does only so in the region just behind the restriction
in the region before the restriction the pressure if anything is increased, thus limiting suction power where you need it.

You must try to understand that a Venturi has not one but two inputs and only one output: a pressurized input, a sucking input and an output in which the pressure is less than in the pressurized input. It is the pressure difference between the pressurized input and the less pressure output which allows for the second input to be sucking (oops, think I am losing you here)

anyway, this is all irrelevant: you don't need to understand the Venturi principle since there is no application for it here. Take a leave, you have merited it.

forget Mr. Venturi for now, he has nothing to do with AP (but I am willing and eager to continue to explain should you wish me to).

In an AP system all flow restrictions are out and should be banned.
They offer no advantages whatsoever and are only wasting energy.


now here is an application that shows you have truly understood the Venturi principle: indeed the pressure difference will allow air (the second medium) to be sucked in.

But alas it is not efficient for aeration: it will diminish flow more than it will suck air in.

It is another transformation of energy. And energy transformations always mean a loss, remember?

Besides, in a well designed AP system (and yours has the makings of becoming one of the best I have seen so far), DO seems never to be an issue. flood and drain take care of that

Greetings

frank

Hay Steve, I don't mind being corrected so long as I can be steered in a more useful direction. I totally agree about the terminology needing to help avoid confusion. As I said, I only used the term venturi drain because that is what it was called when/where I learned about the concept.

+1 for moving the drain terminology to another thread.

Perhaps we should take the super flout discussion to another thread too.

I'm not an electrical engineer, the term audio engineer is probably misleading since much of it is art not science. I often refer to signal flow in audio systems as plumbing electrons.

As to a mechanism for kicking on say a backup battery powered pump could be as simple as a level sensor in the top tank. Like if the wind has been really slow for a while and the water level has dropped down to some point you can arbitrarily decide in that top "wind pumped water storage" tank, then the battery backup little pump could kick on to help bring that level back up. There are many types of level sensors you could look into that can be used to open or close re-lays. Jazzplayermark designed one for me that will turn on my battery powered air pump if the mains power is out or it will also shut down my main pump and turn on battery backup air if the water level in my main tank drops below the water level sensor. He has built a little time delay into the sensor circuit so that wave action won't burn things out turning my pump on and off if the water level is sitting right near the level sensor level and splashing it. This is an important feature for a level switch to incorporate since repeated, rapid on/off action could quickly kill a pump. The sensor circuitry should be able to run off the battery power so long as that hasn't drained all the way down too.

OK. Thanks TCL. Just keep it simple.

Would a deeper tank not offer some protection from the fish going up the drain? Would the smaller fish not stay closer to the surface? Would they go as deep as say 1.5 meters where inflow to the pipe happens?

I don't know Cyara, The little fry I've had, I only really observed them in the aquarium and very briefly in the big tank when I caught them.

They were hanging around in the shallow end of the big tank but I can't say that it was really a depth thing or they just felt safer from the giant catfish hunting down in the depths.

Now an easy way (I think) to have an easily maintained screen on the T type updraft (and even on the standpipe style I suppose) it to work out some sort of screen you can insert just below the T kinda like a pump trap basket or something that you could easily lift out to clean then push back in. Perhaps it could simply be like a block of foam filter material or something even. That is what I'm using on several of my aquarium updraft drains now. Still seems to be working.

Other ideas welcome of course.

Do not simply trust fish not to go there as I've found out a 2" fish can and will go through a 3/4" no holes overflow which means that fish negotiated 6 elbows some how without breaking the siphon on the no holes overfow. The little fry I've had manage to negotiate a no holes overflow into a 5 gallon bucket of gravel, get through the gravel and the screen holding the gravel back from the loop siphon, ride the loop siphon down into the sump tank and one even survived the ride through the pump up into the other aquarium.

If you want to ensure fry survival, you may have to arrange a place for breeding and fry raising with special attention to the outlet filters on the overflows. Then again, tilapia are amazing fish and you may find this isn't necessary as enough of the young may survive. Some may find that controlling breeding and killing off fry is more necessary than the other way around. This could be largely due to temperatures.

Little Houdini's!

You should consider building a coil pump powered by wind, to lift the water. Much easier then a ball & rope pump. And heights as high as 80 feet.

If you like math look at this one
http://lurkertech.com/water/pump/belcher/fish/

All Others
http://www.agf.gov.bc.ca/resmgmt/publis ... 0305-8.pdf

Let me know what you think....