Mack's DTW auto watering system

I am running a DTW coco setup for the first time. Just a simple four plant setup for now to get a feel for it. So far, all has been going well with hand watering a few times a day. Now that I am just about ready to flip them, I thought it would be nice to get more feedings in as flowering gets under way. Since I have the light timer set for 6 p.m. to 6 a.m. to take advantage of off peak electricity rates, my thoughts turned to an auto watering system so I won't have to get up in the middle of the night.

I have read lots of posts here with folks running various drip systems that seemed like they would work, but people seem to battle with balancing output volumes at each plant or drippers clogging. With more research, I came across the Netafim pressure compensating spray stakes. They seemed like a neat idea (and cheap) so I ordered some along with the 3/4" polyethylene feed tubing.

Delivery came and I started mocking up the system. My first attempt was to run a 400gph fountain pump I had around. Needless to say, it may have volume, but no pressure. The spray stakes wouldn't even drip.

Back to the internet... I have had experience with Shurflo pumps in the past. They make a variety of low volume, high pressure pumps that can be run dry if you mess up. Plus, you can fine tune the pressures on them so they will run intermittently and shut off when the preset pressure is reached. Found one that fit the bill for $55 so I ordered it. Pump was delivered so I plugged it into my test system. Success! I got a nice fine mist spray out of each Netafim Stake, but a new problem arose. The Shurflo pump would pressurize the feed line to about 45 psi and because of the back pressure, the spray stakes would continue to spray and bleed pressure long after the pump was shut off. I needed a way to rapidly dump pressure when the feed cycle was done.

Back to the internet.... I found a cheap 3/4" 110v solenoid actuated valve on ebay for $45. With this valve, the solenoid was open when no power was present and closed when energized - perfect! I figured I could put that on a T in the 3/4" feed line and as soon as the power was cut to the pump and the valve, the solenoid would open and dump the remaining pressure quickly.

Valve showed up Friday. Plugged it into the test system this morning and success! The purple spray stakes are rated for 3.2 gph. When I timed them I got 15 oz of water in about 2 minutes. A half gallon of feed water will take about 8 minutes with a nice fine mist broadcasted across the top of the smart pot. I have everything installed and will be getting ready to set the timer this evening once the lights come on and start fine tuning the volumes.

Some background and pictures

Netafim Stakes

http://www.netafimusa.com/greenhouse/products/pc-spray-stakes

Shurflo pump - self priming, can run dry, pressure adjustable (to a point).



Pressure compensating spray stakes tied into 3/4" Polyethylene feed line. Note the little pressure compensating valves where they tie into the 3/4" line




test run of the solenoid dump valve - opens when power is cut to the pump and immediately dumps all line pressure - perfect!


Whole system tied to reservoir. I know my plumbing is a little sloppy, but that black polyethylene tubing is hard to work with and doesn't take sharp turns easily. I need to get a few elbows and neaten it up a little.



I'll report back once I have run a few feed cycles through it and fine tuned everything.

thanks for the info - always interested in good hardware. I wasn't aware that the shurflo diaphragm pumps existed - I like pumps that don't burn if something goes wrong and they run dry.

Update -

So far, the spray system is working very well. I have been watching how much drain through I get and dialing back the times to come more into line with the 10%-20% drain amounts. Right now, I am at about 7 min/cycle with three cycles per 12 hr lighting period.

Pic of the sprayer in action below.

are the shurflo's sensitive to particles, for example, if your doing recirculating vs DTW? I have an inexpensive aqua lifter aw-20 pump (3.2gph), but i have to be careful to prefilter the water if I'm doing recirc.

Yes the pumps can and will clog in a recirculation setup. Filters must be installed. I have aquatec pumps for my hpa system, but I use a accumulator tank and pressure switches.

Also microbes will gunk them up and the pumps have to be disassembled and cleaned.

Another nice thing about the Shurflo pumps is they are rebuild able if the pump fails.

Been running this system for about 10 days now and it seems to be running flawlessly. I am using an 18 gal tote as a reservoir so I need to top it off every other day or so. At least this keeps my mix fresh. I figure I am using about 1/2 gal per plant, per feeding for a total of about 6 gal per light cycle. Because of the three feedings per 12 hrs, I have scaled the ppms back on the nutrients to about 750ppm (500 scale). Plants look like they are liking it.

First picture from 3/14


Next picture four days later - had to raise the light they have grown too quickly.

Lose the sprayers. All you need are open 1/4" lines running into the pot. Coco will satuarate itself evenly no matter where you put that line in the pot. I personally use a T and let it poor out in two spots(like a horse shoe), but it's not needed. I see no difference in yeild or roots, I just like messing around with stuff-so I can understand the sprayers-if they clog just toss them : )

FWIW, I picked the sprayers because they provide a nice, even coverage over the entire pot. Plus, the ends (where they tap into the main supply line) have little pressure compensating valves that ensure each pot gets the same volume. Since I am running about 45psi with the pump I selected, I suspect that clogging of the spray stakes won't be a problem.

You are likely right that I have over thought the design, but it works really well and I have had zero issues to date.

Those diaphram pumps are very loud. No good for a stealth grow.

They are a little buzzy, but they are reliable, efficient and can run dry if you screw up without much worry. Since they are in my basement and only run about 6-8 min/watering, sound isn't a problem for me

I'm still getting a feel for it myself/trying to figure out what works best. I made the mistake of using 3.75gal containers, I wish I went smaller because I need to water a minimum of 2mins to get them saturated-when I water once a day early in veg I run it for 3-4mins.

I slowly increase to 3, 2 minute waterings through out the day. Once right after lights come on, then once in four hours, then once an hour before the lights go out. So 3x, all while the lights are on.

I was curious what your watering schedule looks like?

Squidbilly -

I'm running 3 gal pots (but probably could run 2's). My first run, I transplanted from 1 gal plastic pots to the 3 gal smart pots. I then watered by hand every 2-3 days for about a week until the roots had a chance to get going. Once they were established, I turned the watering duties over the the pump and started watering once a day. What I did was to run the pump and watch for the "right" amount of drainage while timing. The time it took to get 10-15% waste was what the pump timer was set at. In general, it seems as though the 3 gal pots with coco take about 1/2 gal/per feeding (minimum) once they get rolling. Once the plants really start growing in veg, I may jump to 2 waterings per day. The nice thing about Netafim spray stakes is they are pretty low flow so the coco gets saturated slowly and evenly. Right now, I am running the pump about 11 minutes before they will drain the amount I want.

In flower, I was watering 3 times a day. Once at lights on, once at 4 hours, and once at 8 hours (of a 12 hr light cycle). The other thing to mention is I am running a lower nutrient ratio than most companies recommend. Even through flowering, I was running around 900 ppm at most and it seemed to work well.

I am by no means an expert, and I am pretty sure I can continue to dial it in, but the plants look healthy and growing well with no significant deficiencies or burns.

I really like your system. Im in the middle of doing mine also with netafim pressure compensating drippers. How is it working out for you? any clogging of sprayers? what type of timer you using?

GrifoMata

No problems with clogging at all. The purple spray stakes have worked flawlessly so far. I think the key is pressure. My pump is putting out about 45psi so it keeps the spray heads clean.

As far as a timer, it's simply a $20 digital from the local Hydro shop that allows me to schedule multiple feedings per day and is programmable by the minute.

Awesome, thanks for the response. Ive had a hard time finding people that are running a pressurized irrigation system. I hope you dont mind answering a few questions, Ive runned into. I see youre running the purple stakes i think rated at 3.2 gph. Those sprayers stake spray water from one direction as oppose to their 6.6 gph one that sprays out from two directions.
So it brings me to my point. How is the water saturation of the pot? Do you think it sprays evenly or water's it evenly?

I run 5 gallon buckets with a diameter of around 12 inches. My dilemma was getting the purple sprayers or the orange sprayers rated at 6.6gph spraying from two directions.

For 3gal smart pots, the purple stakes provide plenty of coverage and feed slowly so I'm pretty confident that the medium is getting thoroughly covered. Spraying with the double sided yellow stakes would likely over spray my pots.

Pic of my pump board if it helps

Edit* Never mind I re read your original post. Thanks

Can you please explain how you wired the dump valve to close when pump turn on & open when pump turns off? Thank you.