Backyard Aquaponics
A place to discuss aquaponics

Concept: Am running my pump and aerator from a small solar system. Do not want the pump to run continuously. The grow bed is flooded once each hour 24 hours a day. The drain remains open but is restricted by a valve which allows the grow bed to drain completely in half an hour.

Problem: When the float switch is satisfied and turns the pump off, the pump would normally come right back on when the water level drops a little. But in this case the pump must not come back on until the top of the hour. What kind of timer switch do I need? Or, should I change my concept? Thanks a lot.

Hello

You could use the timer to start your pump every hour and switch the pump off when the float switch reaches the maximum level. Depends a little bit on the timer, if it is a digital one which allows you to activate the output for just one minute, you could use a latching relay and unlatch the relay by using the normally closed switch on the float.

You could use a 12 volt timer, 15 min on / 30 min off

Drill a small drain hole in the base of your growbed standpipe which will drain the water on the off cycle.

This is what I have been doing on our solar aquaponics system with good results.

Good 12 volt timers are hard to find (at least here in australia), but decent auto-electricians, electricians and hydroponics suppliers should be able to point you in the right direction. There are those digital 12 volt timers for sale on ebay but they usually have a certain amount of cycles whereas what you want is a continous on/off cycle.

Welcome Tender!
Plenty of people here just use those standard 240v mains plug timers that you can get everywhere. Just set the fill and drain times to comfortable suit your system

Are you using a battery in your solar setup?

If not, why don't you just run the solar pump continously directly connected to the solar panel with an auto-siphon to handle the draining?

Or, if you have grid power available, you could run the pump off the solar panel during the day (timed, or with an auto-siphon, or just continously flooded) and run a low wattage airpump & airstones off the mains power 24/7. This way your fish have sufficient oxygen when the solar pump is off.

For those with grid access, I'm convinced this is the most economical solar/grid combo instead of investing heavily in deep cycle batteries which have a limited life

But to do this on solar, you would either have to run 240 volts to run the mains plug timer, then a relay off this to trigger the low voltage volt solar pump to turn on

..or run the 240 volt timer connected to an inverter connected to the 12 volt battery?

..or, more complicated option, modify the 240 volt timer to run off the 12 volt battery eg http://www.reuk.co.uk/Convert-Digital-M ... oltage.htm


am I missing something here?

Yeah, I have no idea what the "small solar system" consists of. I just put it out there

Great responses. Thanks so much. There is always someone awake on this forum. Pictured is my 45 watt solar system from Harbor Freight Tools connected to one deep cycle automotive battery.

The invention engine says you could extend the floatyness of your float switch so it is at the bottom of the grow bed, then make your drain hole small enough that it takes the full hour to drain. That way the pump doesnt kick in until the tide is all the way out.

The grow bed should be fine under water for that long. And all the growbed will see air once every hour, so there's really no need for a timer if you have a float switch.

If you have a small electronics style flat switch, you could extend it with some super glue and a fishing float like this one...

Brilliant.

Good idea Bullwinkle... though could you explain it a bit more for the slower members of the class, ie me

The float switch turns the pump off when the grow bed is full
Growbed drains slowly over the course of an hour..

But how does the float valve trigger the pump to turn on again when the water level is ONLY at the bottom?

Or in other words - how do you keep the float valve 'latched' off until the growbed is completely drained?

thank you

I'm not sure I can.

I'm not sure it will work.

With things like a float switch, you can work the electronics so that the switch turns something on when it floats, or off when it floats. In my suggestion, it would turn on when the grow bed was entirely empty by submerging the float all the way to the bottom, and working it so that it would only turn the pump on when it was out of the water - when the grow bed was empty.


My solution probably isn't one

I think I should try again

The pump would turn off straight away after it started. As soon as the water floated the switch.

Oops!

Normally when I run through problem solving stuff, I put the answer through the same process as the question to see if something new is a problem. In this case the fact that the pump would turn off again, but when I got as far as something I was familiar with I made the mistake of leaving the process and posting a quick reply.

The thing I found familiar is to do with float taps. By extending your float tap down a bit you can automatically top up a sump even when the height of water is changing. You just set it deep enough so that it only opens when the low tide mark is too low. Unfortunately once I recognised something that looked like a solution to something else, I was lulled into a false sense of finality


So to re-cap...

Opps

It's ok, all good mate.. I think I speak on behalf of everyone here that we appreciate all your out of the box ideas



I think you may actually be onto something here.

Perhaps using some relays with N/O & N/C contacts (Normally Open, Normally Closed), you could wire them up in such a way they continually tun the pump on and off as the float valve hits either empty or full electrical contacts.. you know those hallway lights where there are 2 switches, one on either end of the hallway which both control the same light? Some times you need flick the switch downwards to turn the light on, yet other times you need to flick it upwards to turn the light on, but they never stop working they are always stuck in an endless loop sorta thing?

Yeh well cross that endless loop type thing replacing the two switches with the two float electrical sensors (full/empty), and a couple of cleverly wired relays and.... what would happen?

need to sketch this one out but I think this definately has potential

One further thought - does anyone know if you can you get a valve/electrical register switch which performs exactly the opposite function of a float valve ie which registers when something has drained? An anti-float valve?

That would solve the problem..

Though I suspect this may be entering the realm of electronics and micro controllers/Arduino which kinda defeats the point of the whole exercise - to simplify and do away with a low voltage timer

waitaminute... I think I've found her here:

"High flow rate dual level reservoir valve"

http://www.anadexlabs.com.au/shop/catal ... 16157.html

.. but at $AUD 186.48 a pop, an auto-siphon is looking rather hot right now lol

Then there's these much cheaper electronic liquid level sensors:

http://www.ebay.com/itm/P-P-Vertical-Wa ... 0911059306?

http://www.jaycar.com.au/productView.asp?ID=KG9138


.. but I suspect after you've bought all the sensors, relays etc.. you might have been better off just buying Jaycar's 12 volt "Flexitimer" kit for $19.95 (http://www.jaycar.com.au/productView.asp?ID=KA1732), locking yourself in a quiet room for a few hours and soldering it up. When they say it comes in "kit form" they really do mean kit form.. you basically just get a packet full of resistors and capacitors and some vague instructions and are left to your own devices. And yes I'm talking from experience here hehe