Backyard Aquaponics
A place to discuss aquaponics

The primary cause for dissolved oxygen being reduced overnight in pond culture has mainly to do with algae and the fact that while during the day plants give off oxygen and use carbon dioxide but during the dark hours they will use dissolved oxygen and give off carbon dioxide (this is also what causes diurnal pH swings.)
But since my fish tank is heavily shaded and isn't growing tons of algae and most of the grow beds are flood and drain media beds, I don't have much worry about this effect. Where no plants are involved (especially algae) and water temperature is the only variable, then yes cooler water can hold more dissolved oxygen provided there is plenty of aeration to keep it in the water faster than it can get used up by the fish and bacteria.

Hence why I'm not that much worried about it in my system with the pumps running and air all the time as well as the grow beds being mostly flood and drain so the plants have ample access to air and so on.

The general plan is for temperature brackets to be user defined so that we can restrict feeding to between x, and y degrees.

For my silvers I'd say no minimum limit but a maximum limit of say 30c or something (more education required here) more for the system's sake rather than the fish.

They wont hit the lever if it's too cold, they tend to lurk on the bottom.

But if it's too hot they go nuts and hit everything.

But regardless, no matter how much they hit the lever, they cant get more than the user set maximum amount of feed to be delivered in a day, so I dont think there is much harm to be done.


I only know silvers, and I only have just over a year's experience with them, so if there is any stuff I'm banging on about that doesn't apply to other species, can you please shout it really loud and make me understand it. (Keep pushing it, sometimes I dont listen) I want this thing to be adjustable to suit everyone.

Give me some bullet point facts I need to be aware of if you see me straying from things that apply generally, to things that only apply to silvers (or dont apply to the universe at all)

Also I'll be adding the temperature probe next, so any input on where the feed/dont feed limits should sit for different species will help with the plan as far as how to go about setting up the user adjustable limits. But keep in mind the fish will only be able to get the upper limit of feed set by the user, and will only get that distributed over the day in one form or another. This means that for my silvers, I should not need any temperature controls at all. They cant feed more than a days worth if its hot, and they wont be interested in anything like a days worth if its cold. But if the day starts cold then warms up, they should be able to get a days feed in the last half of the day.

The only temperature based limits I would want to set would be something like "If the system is dangerously hot, dont feed them a thing" just because not feeding is always a good thing when there is a general fear of a system failing.

Yea, that sounds pretty good. Since if it gets too darn hot we are worried about almost anything being too limiting on the available dissolved oxygen so setting a high temperature cut off would be appropriate.

Now for species other than silvers, I'm not sure. I've not actually done extensive testing of demand feeders with my fish so I don't know if they would be likely to hit a lever even if it were too cold for much eating. If it were not too difficult, I would probably say to set a minimum and max temp range and outside of that, no feeding at all. (Just in case you get another kind of creature that decides the lever is a handy way to get treats but is messy and leaves too much of the pilfered food in the tank to foul it for the fish.) But I wouldn't stress over that feature too much at the moment.

Thanks yet again.

It's a good thing you don't live just down the road, because I'd be constantly hanging around your kitchen table asking you questions

It's 4am, there's a tap on the window. It's raining heavily, and worried looking man is standing at the window, a silver something in a Tupperware container. He's asking if TC would mind getting out of bed again to look at his fish. "What about this one, does this look like Ich?" he asks for the sixth time tonight.

And that, children, is why the southern hemisphere is kept so far away from the north.

Max and min is easy enough to do, so I'll add the ability to do both.

Hmmm other beasties trying to eat the fish feed. Perhaps I need to work an electric fence into the deal

or a Taser...

What you're doing with your maths is simply dividing up the day into a number of segments equal to the number of feeds. That is perfectly acceptable if you feed them at the end of that time.

eg 12 hours of daylight, 6 feeds = Feed every two hours. But the timer is set as being after that time (I'm ignoring the fact that fish could trigger at any point). But what you're actually doing is dividing the feeds, not dividing the time *between* the feeds.

Consider 12 hours, 1 feed. The wait would be 12 hours ie. at the end of the day. Where the feed *should* come is after 6 hours. So to get the time to wait you actually need to divide by the number of feeds + 1. NB. this does not mean that you feed them twice.

The original request was for the time to wait *between* the feeds. Of course if you're happy with the feeding after the waiting time then by all means carry on and ignore my witterings.

I think I'm going to have to look at this in daylight. I'm so confused

It's 5am here so perhaps all this talk about time will have to wait for a better time.

But I'm so confused

If I follow what you are saying correctly (and that is a very big if ) I dont think it matters, because the next days feed is starting from a position of waiting for the ForcedWaitBetweenFeeds. Or at least it is now. Perhaps the posted code doesn't reflect this.

If the +1 refers to setting the feed before or after the wait, It doesn't really matter because the next wait follows from the previous.

Eating every hour at the beginning of the hour or the end is the same thing.

This business about feeding only during the day is a new concept to me. It's not something I had thought would be useful. In fact I thought it would simply concentrate the ammonia load rather than spread it as evenly throughout the day as the fish were willing to.

My original thoughts were that the cycle would be roughly 24 hours, and that the feeds would, if they were taken advantage of as often as they were offered, fall roughly evenly throughout that 24 hour period.

The dynamic nature of the improved model, would enable the fish to get fed more often if they hadn't fed as much as they could have. The end result would be that the last feed offered would fall on the last minute of the last hour of the day just before dawn. Then a new day cycle would start. The new day would start with a wait of DayLength/FeedsPerDay.

Or not.

It doesn't really matter. If the final wait is at the beginning of the day it would not be at the end of the day. If at the end, then it would not be at the beginning.

The opinion sought related to a secondary overriding limit whereby the fish might be forced to wait a set time no mater what. A minimum time of forced wait regardless of how many feeds they had left in a day.

so something like...


1.feed every DayLengthInMinutes / FeedsRemainingForTheDay unless that time is less than 30 minutes. If it is only offer them feed every 30 minutes to prevent system overload.

or...

2.Feed every DayLengthInMinutes / FeedsRemainingForTheDay regardless. The system will cope.

3.Something else

Don't suppose you drew a schematic ?
If you ever ask an electronics person about a circuit they will always ask for one. Otherwise I will try a visualise it...but its getting late so thats not likey. I might just draw it instead

Ok, regarding the vero board layout. It all looks pretty good mate.

-sorry in advance, am typing this on my phone so beware random words from the auto correct

Are you using a MOSFET or a BJT transistor to drive the motor ?

One thing I would add is a pull down resistor to the gate/base of the transistor, especially if you are using a MOSFET. Otherwise when you turn your circuit on it might do things like turn the motor while the uP (microprocessor) its starting up. Even if it seems to be ok, do it anyway. the resistor ensures the transistor is always in a known state, and its good practice.

MOSFETs are easier, you dont have to worry about saturation current etc.

I'm assuming you sized the current limiting resistors on the LEDs correctly ? -just a standard check.

Is the chip programmed with the stereo plug over serial? (haven't used these before)

I know what you mean about things touching each other on a breadboard, so frustrating...

And get yourself a flux pen, something like this

au.element14.com/chemtools/ct-fdp/flux-dispensing-pen-no-clean/dp/1827776

There is soldering, then there is soldering with flux..... it truly is magic. In fact I might order that one.. Jaycar/electus carry them too.

you dont need it, but you won't go without one once you have used it.

The motor is a 12 volt one with a reduction gearbox so it spins at 36 rpm, but for the time being I'll be running it at 5 volts. There are some servos that have been "factory fixed" so they rotate like a motor on the picaxe forum that I think would be ideal to power this. My motor is overkill. The servos cost 10$au each and I think are rated at 3kg of something. My motor is rated at 27kg of something

Newton somethings or torque ... I cant stop it with my fingers at 5 volts.

the transistor is labelled BC337 but SABorn from ozelecforum.com suggested "BD139 is around 1.5 amp or BD681 around 4 amp, either should do."



yep yep and yep

so the pull down thing... is that like the resistors on the serial pins, so they are not left susceptible to static or radiowaves or whatever other random voltages arer wandering around the universe?

Can you show me what that would look like.

ie a resistor to ground?

and what value?

And how would you decide what value for my future reference?

I think I promised a video of the feeder working.

I have three.

I cant figure out how to edit them

So I offer none for the time being.

I'll put them up later. tomorrow perhaps.

The feeder isnt connected to the electronics yet so there is a lot of dead space on the videos where my touching the wire to the power supply did nothing so I'll edit it and make something that will run under the three and a half hours that it might end up If I keep editing with the software I have now.

I wish I knew how to do everything.

Not far off completing my first ever electronics project from scratch.

Yay me.

Yay everyone who helped me so far.

I've bought you all beers. but in order to protect you from their deletirleriousl effects I'm as to still keep drink them on your behapff.

hic!