With such a short cycle time, the motor will fail early.

Thanks!
I think a cycle timer is exactly what I need. Umm... not much of an electrician... would this timer do for my needs? http://www.ebay.com/itm/AC220V-Repeat-Cycle-On-Off-Delay-Panel-Relay-0-30-Min-Timer-Installed-ATDV-Y-WUS-/331406797685?pt=LH_DefaultDomain_15&hash=item4d29626b75
It seems perfect but I'm afraid to make some rudimentary mistake (like for instance that this is one of those dangerous items that can't be left alone for long periods lest it will cause a fire or it is dangerous to leave outside even under cover) . It also says that " Power Expend:DC1.0W, AC1.0VA" so I assume they mean that this is the power the unit itself takes/loses?

Grateful for any comments.

willardb3-
I'm not sure if your remark was meant for me or for hex2006 :P.
If indeed it was for me then what arrangement do you think is more suitable? Isn't continual intermittent watering every few seconds is what the aeroponics guys are doing?

enni chausterlast,

Let’s start with the type of setup and go from there. I am
assuming you are doing an Ebb and Flow system? Is that correct? Any info can
help with this or where you would like to go.

I think willardb3 is saying that if you are turning the pump
on and off frequently you can cause excessive strain on the pump. The most
taxing time on a pump is the initial “jump” it needs to start the water moving (I
am no pump expert though and will let an expert way in on this).

Now getting to the cycle timer… I would suggest just going
to Home Depot and picking up a prewired irrigation timer. After mastering the
controller you can upgrade to a home wired one. I would also suggest getting
one from home depot at that point and having them demonstrate the wiring to
you.

http://www.homedepot.com/b/Outdoors-Garden-Center-Watering-Irrigation-Sprinkler-Timers-Irrigation-Timers/N-5yc1vZc63p

I hope this helps! Post back with what you are looking to do
and we can dive into the engineering of the solution.

With aeroponics you`d use a high pressure pump to charge an accumulator tank. The cycle timer only controls a solenoid which releases pre-pressurised nutes from the tank to the nozzles. A pump that runs 5 minutes a day will last for years. Solenoids are very reliable and can handle literally 100`s of operations per minute. The main issue with just using a pump is it cant react fast enough for very short mistings of 1 second or less.

I would just like to reiterate a point made my Jeremiah Landi. Turning a pump on and off repeatedly during the day WILL cause it to fail prematurely. I lost 2 pumps doing this before I realized what was happening. I disassembled the pump and found excessive wear on the plastic bushing that holds the impeller. During startup the pump has to get all the standing water in the tubing moving, this strain causes wear. I had my pump running for 15 minutes and off for 15 minutes. So it was starting 48 times a day, and it lasted about 3 months before failing. The first symptom was a lot of vibration and noise from the pump. The next symptom was that after turning off, the pump wouldn't start again. The impeller would bind during startup and just sit there buzzing.

After replacing the pump for the third time I took out the timer and let it run 24/7. It's been running for 3 years now with no problems. Same brand and model of pump, just not cycling.

Good luck with your hydroponics setup!

Thank you very much for your response!
Indeed I am setting up (as cheap and low maintenance as possible) an ebb and flow system.
It will be put on the balcony (hence my query about the safety of placing the timer outside)...
The system is comprised of two buckets (reservoir and pot) with height difference so some pressure is required. The idea is as simple as can be: pump shoves water up (the reservoir is in the low shady part), gravity pulls it down, the timing however is something I would like to be more flexible with, so for example i want 5 mins of work and say...8 mins of rest, or something along the lines...

As for the irrigation timers, thank you, this is a great idea to see how timers work in general. The thing is I kinda already know the principle (:P) (that is exactly what I was looking for)- I'm just not sure if I haven't missed any pitfalls with the specific unit that I picked. Price is also an issue.
Actually, I have browsed ebay and various electronic sites since and maybe there is a better (well, cheaper) option in the form of a 12V digital arduino timer, but I'm still not completely sure...

About the pump issue...that is new to me and sounds like a problem. Pressurized tanks and high pressure pumps seems like quite an expense (also isn't it dangerous within the house?) and I'm not sure how well would it work in a flood drain situation.
So What do Ebians do? Just replace the failing part each X amount of time? The general Idea of what I'm doing is taken from here : https://www.youtube.com/watch?v=tAzxwpgnVhc

thx alot!

edit: kleeem -

sorry,saw your message only after posting, so you say that you switched from Eb and flow to a different method? like NFT? Also, what about the electric bills?

For flood and drain you`d only need the pump to run long enough to flood the tray, typically the nutes flow back to the res via the pump when it turns off. You only need to flood the tray 4 times a day which a standard 24hr timer with 15 minute segments could handle easily.

enni chauster,

The main concerns I have when doing a hydro setup is a two
fold question:

• Electricity
• Nutrients (Not a concern in these approaches
  really…but always debatable.)

I think this depends on substrate you are using. If you are
using soil it can be different than if you are using a coco fiber/chips (http://www.homehydrosystems.com/mediums/mediums_page.html).

Now, my concern with the electricity is if it is hobby or
for sale and if lights are running. For farming it is a different league;
however, if you are running a light it can be quite expensive. I am assuming
that you will be using natural lighting so really it just comes down to the
pump running, which I don’t consider a big expense.

Now you can approach NFT and Ebb/Flow with a minimalistic
approach. I will say NFT will be harder because you have a wicking material
involved or circulating water constantly. I am not going to dive into too much details
unless someone wants to. J

FenderGibsonWashburn, just for obligatory name drop, did
have a pretty good video and I think your modification will do great. It is
actually a very common (which it sounds like you know) modification.

I am in the boat with hex2006 and kleeem around the timer/pump.
Another item to contend with is making the box water tight or environment tight
(aka keeping bugs out). If you approach a do it yourself system parts might
bring up the price. Have you looked into just “digital plug timers”? They are relatively
cheap and come with a warranty.

Could you walk us through how you envision the system
working though?

The two ways that I have seen is either:

1. Put the reservoir at the bottom and just allow
   the water to be pumped up to the top of the plant substrate for “x” amount of
   minutes before the pump turns off for “x” amount of minutes allowing the water
   to drain (can be more complex with sensors but this is an easy hobby one); or
2. Put the reservoir at the top and the pump at the
   bottom. The pump would turn on with a float gauge, much like in a toilet,
   causing it to drain the water once it hit a certain level in the plants and
   then turn off when the water got to a low level to prevent pump burn out.

Number 1 is what I have seen the most in hobbyists but I
will allow someone else to chime in. I am having a hard time understanding how
or when the pump would be switching on:off rapidly in your scenario.

hex2006-
Just 4 times a day? Is that the practice? I've heard about switching on/off every 15/30 mins and that sounded somewhat less than optimal to me...

If you flood the roots for 15 mins, wouldn't that be too much for many plants? Conversely, leaving it to dry for 6 hours, isn't that detrimental or at least stressful for many varieties (and even if there is enough moisture, does the plants have enough access to nutrients)?

Jeremiah-
Yeah, the power consumption was high on my priorities when I considered hydroponics. It's not like I'm gonna sell the produce but I am in a dire lack of excess money to burn- that's why the pump power consumption actually did seemed important to me (unless I'm growing weed then that is a whole different matter).
I calculated that if a simple 10W pump ran for 24/7, 365 days, it would amount to 87.6KW. I pay 20c for KW/h, so a yearly cost would be around 17.52$. The price of tomatoes at my local market is a little more than 1$ per kg. That means that simply to cover the usage cost of this one pump I need to grow more than 15kg. You can see why I'm not a fan of letting the pump work more than it needs to.

Lol, I missed your meaning, when you said "making the box water tight " ,did you mean the timer box or the grow box? because in both cases I just use a discarded bucket/cereal box with some water proof glue on the lid. Ghetto to the max!

And when you say “digital plug timers” you are referring to this type of thing?: http://www.ebay.com/itm/Digital-LCD-Display-24H-7day-Programmable-Timer-Electronic-Plug-Switch-110V-US-/361252796244
If so, then like the with my opening post, they have up to x powerons per day. Very annoying.

,

,

,

The second scenario you described is actually pretty nifty, but I fail to see the advantage if indeed rapid switching will burn out the pump.
My case however is the common first scenario (mostly because of space constrictions (the sun is at the top)). I don't know if it is that 'rapid', but if the pump fills the bucket in 4 minutes (and turned off due to power conservation) and the drying occurs for another 11 mins- then we are talking about 90 cycles per day (I have no idea if that is a good growing practice, but speaking hypothetically).

I took your warnings about the quick burnout to heart, but I'm not sure what's the alternative in an ebb-flow system (other than cycling it to 2 operations per hour). One thing I thought of changing is the placement of the pump. according to Kleeems explanation ,a partial cause for the failing is the column of water already present in the pipes, overloading at each start up. Seems like it can be solved by placing the pump in an upside fashion near the top...

thanks guys.

Another question. Does anyone knows anything about those type of timers?
http://www.ebay.com/itm/NEW-OMRON-time-timer-relay-8pin-H3Y-2-H3Y-DC12V-5A-0-5min-10min-10min-/350680823642?pt=LH_DefaultDomain_0amp;hash=item51a634b75a


Seems like they belong in a fuse box, but I don't know if they can be used independently for my uses.

thx.

With flood and drain, the tray fills and excess runs through an overflow back to the res so 15 minutes wont hurt as the water is moving. Hydroton will stay moist for hours, plants dont need watering as often as you may imagine. I have hot peppers in 10L buckets full of hydroton that are manually flooded twice a day and even that is bordering on too often as the weather isnt great..

Huh.

Just 4/2 times a day...

I was definitely under the impression that for proper grow the plant need to go as many water/oxygen cycles- but... huh.

Thank you, I'll think about it. If that is what most people do then maybe a 15min timer will indeed be fine...

thx!

Enni,

I'm not using ebb & flow, I'm using an aeroponics/NFT system.

And after thinking about it, you may not have the same problem with pump failure that I experienced. My setup has to pump the water up and through a PVC tube that has holes in it that spray streams of water at my net pots. So, I have to overcome the water column AND provide enough pressure to spray water out the holes.

YOU only have to lift the water up to your plants. no pressure for sprayers. your outlet tube should be unrestricted. this will eliminate a lot of strain on the pump. There will still be some strain because it has to lift the water. and you can eliminate this as much as possible by reducing the height that it has to lift the water.

Good luck with your setup!

Enni,

Thanks for doing the calculations on the pump and I see what you mean!

Let us know which way you go with or if you are still looking for a decision. This thread has been amazing and great for learning I must admit.

kleem-
Ah, well that make sense, the misting pressure required is huge. I will still take precautions with my pump ,although ow thinking about it I probably should order 2 pumps and use the first one carelessly just to know the exact limitations for the future :P.

Thank you very much.

jeremiah-

Thank you, at the moment I'll go with the plan I had in the beginning but I'll change the watering cycles as per hex2006s suggestion, so a cheap mechanical 15 min interval timer will do, and I also plan to place the pump at the top to avoid water columns.
Then again, maybe new problems will be discovered at the moment of construction (as they tend to ) -so it'll be seen when ebay sends me all the parts I have ordered.

thank you very much!