Backyard Aquaponics
A place to discuss aquaponics

I want to create a system that has a water sensor at both the top and the bottom of the grow bed. The top one would open the drain and the bottom one would close it.

I've concluded that I likely need a normally closed solenoid valve (stainless steel) but I'm not sure what I'd need for an inexpensive solution to the sensors.

I've found a few but they're not anywhere near cheap.

To also maintain a failsafe (so the system doesn't flood) I'd have an overflow pipe setup like I've seen in some diagrams here (with the air inlet at the top of a t-joint). I'm also setting up a sump space because I want a constant height pond.

I can't find the answers to questions I still have though:

How big of a valve do I need to drain a 20' x 5' bed in a few minutes?
Are autosiphons/bell siphons better than electronics? So many people are using them, and I haven't found anyone else doing this idea, so I am doubting the intelligence of my idea.
Is there something better than the normally open solenoid controlled water valve, specifically like a plug?

Thank you all for the wealth of information you have already provided! I'm looking forward to learning more.

Regards,

Paul

I made my own sensors and valves, all controlled by a micro.
My thread has a few pics and details.
Valves were actuated by RC helicopter servos, so not exactly an off the shelf solution.
I tried solenoids from washing machines, but they don't work at low pressure.
Washing machine release assemblies would work, but are expensive.
My valves cost 150 Thai baht, (3-4 dollars) but need a micro to control them.

A pump to pump it out would be cheaper then a valve like that if I can remember how much they are. I used to use valves like that for nh3 and they are pricey at 3-400+ each. It might be easier to make a height control set up bucket nest to the growbed with sensors in the bucket connected to the growbed with the pump in it. a guy made a nice DIY write up on a forum that may or may not be legal to link to depending on laws in your country/state/county or locla regulations so if you google ogre DIY ebb flow buckets that would provide you with a nice walk through on a way to do it with proven parts that will work well. They only downside is biofilm will mess with the parts and extra pumps an such are added failure points that is one reason why they way aquaponics works well like the people here are doing it. Ebb and flow buckets and set ups like that really work well as you can control the wet time better and with regular hydro root rot can be a huge problem so keeping stuff a bit dryer is key but with this stuff the fish poo bacteria keep lots of root rot at bay so wetter is more OK.

When it comes to sensors and even solenoid, cheap often means that reliability would be a problem after some time. I would suggest that the reason not many people has used electronics is because the flood and drain concept can be easily done using a pump and a timer or a pump and siphons. Why complicate something simple?

Thank you for all your replies.

To answer ivansng question:

I'm interested in this because I want to keep an automated log of what is happening with the system anyway. If I can create a simple switching system that opens a valve (or plug) I can fine tune the system to a more particular state than if I were to do it entirely mechanically. I would even be able to set it up so that the sensor would allow a particular level of drying before closing the plug and refilling the grow bed. It all really boils down to more granular control. You're all right though, why complicate something that already works? Part of the interest I have is that my background is as computer nerd so I have a predisposition for blinky lights and data streams.

Thanks for the tip pancakes. I'll check that out. I'm guessing, based on your description, it's not likely to be safe for work.

I'm really excited to check out your solution DuiNui!

I will see if I can locate the same guide on another site. You could just go with the regular siphon set up and such then use the sensors to log data so it will stay with the bulletproof KISS design but allow you to keep track. There should be float switches available on omega or other parts places that would let you log fill times and empty times without to much trouble. You may need to make a well in the growbed for it with some tubing. The flow could be adjusted to fill and drain faster or slower with the ball valves after you find what you think works plus then have the availability to repeat your favorite fill and drain times later on without problem.

I have worked on so much overcomplicated crap that many of the problems are all the new fangled crap added on tripping out the safeties that keeping anything simple gets my vote but logging data without interfering in operation is a great idea.

here is a part kit for ebb and grow that just needs a bucket and some wire I think. Their guide link is down I will try to locate one. Check around for a better price I know they where under 100 for the kit last time I bought one. http://verticalhydro.com/index.php?main ... ducts_id=4


edit: here is a better link with more detail. http://www.aquahub.com/store/diygbuildebb.html


I have no idea how well this will hold up to fish wastes.

What about a timed flood and drain system or a siphon with couple of float switches then? One float switch for low water level and the other for high water level.

That way you still get your logging performed but if they stuff up, your flood and drain system will continue to work.

Many solenoids and/or sensors don't perform well in aquaponics over time... as they either clog with suspended solids... and/or bio-film...

I started the automated thing as a bit of fun, but when I calculated my sump size wrong it gave me the opportunity to flood 3 beds in sequence rather than all at the same time, I didn't have enough water to do all 3.
The valves worked really well and actually improved over time with a film of bio slime, helping to seal the tiny gaps between the ping pong ball and the 20-50.

The sensors on the other hand gave me some grief, analogue electronics (I'm a digital guy) is not one of my strong points and lack of the right development equipment made it even harder.
Also whenever metal comes into contact with water, crap builds up, I suspect that the sensors would eventually fail completely, but routine maintenance would prevent that, similar to that of the pumps.

I am rebuilding and expanding my system currently and had planned to leave the electronics out as it saps valuable time that could be used to dig holes etc.
I couldn't leave it alone though and have spent most of the day today refining the software and hardware and therefore have achieved virtually nothing today

I think siphon is the better than mechanic/electronics, no moving part, no electricity usage, cheaper.

The cheapest sensors would be either the electrode type or the toggle type.

The electrode type are two little wires which send a signal when water connects a circuit between them. They can be set up to operate a valve when the circuit is broken (low water point) or completed (high water mark)

The toggle type is like a tiny version of the float switches on sump pumps. There is a float on an arm and when the arm is straight the circuit is complete. High water switch is positioned so that when the water level is low the float hangs down. Low water switch is positioned up the other way so that when water level is high the float is up.

Aquasonic has a version of both types on their website.

And most of them struggle to cope with normal AP water.. for more than a week at a time...

I wouldn't be relying on them... why not just use a high/low float switch on the pump... standard stuff..

Hey all, been working on a float switch setup to monitor grow bed heights thats easily maintained. It's been in the growbed for about 4 weeks and seem to be working well so far. I periodically test the circuit makes and breaks with my multimeter.
It's made with a ebay float switch from hong kong and some pressure pipe and fittings. I've put an irrigation fitting in the top and i'll use irrigation pipe for mechanical protection and cover the joint in the cables.
I'm going to use a micrologix 1000 for control.
If anyone's interested I'll put some more detailed photos up soon.

You cant do that sned!

get some info up mate

I presume you mean the water level in the grow bed when it floods and drains.... when you refer to measuring "grow bed heights"...

My question is why??.. what purpose does it serve??