DIY fertigation controller

ive been mulling this thing over since like last November... stock piling parts and other junk... however it wasnt untill like 2 weeks ago that i actually started building this thing. i have the fairly distasteful tendency to procrastinate on projects... or just drop one and start another.
anyway i thought i would just start a build log, hopefully it will keep me motivated to keep working on this thing.


so heres whats going on. this thing hopefully will ultimately control EC, PH, Chlorine injection, and Irrigation. it will ultimatly be composed two separate assemblies, a high pressure distribution assembly, and a low pressure sensor loop. the system will maintain a 30 gallon reservoir of fertilized water at what ever PH and ec i choose, and then pump it out to where ever i choose, at what ever volume i want up to 5 gpm.

heres where i started.



prior to my most current bout of building. i had a super ghetto setup useing a 5gpm diaphragm pump connected to my res. i would simply mix a batch of fertilizer, adjust the ph, and then let the irrigation controller pump it out to the plants. one res of 30 gallons would last around 4 or 5 days with he amount of emitters i was using back then. TBH even at that point, it was a really convenient setup. it takes about 15 minutes to mix up the fertilizer and adjust its ph once you know what you are doing. anyway that setup ran off of a hose that i coiled up next to the system which was ugly as hell. so i elected to just bolt some sch 80 pvc to the wall... which IMO looks alot nicer. im intending on this being a farily perminate setup, so i installed the thing with masonry anchors. it just runs the legnth of the brick veneer up to where the system sits. there are a few valves and unions that allow me to drain it when its too cold, and to divert vater to where ever i want.

heres a shot of the connection



its hard to see but its connected with some braided hose.



heres a shot of what i guess ill call the... distribution assembly? its just a ton of valves that allow me to direct water from the res into the pump, and out to any of the three zones that you see in the lower left. you will notice that the top most pvc pipe is connected to my tap water pipe thing. this is so i can push fresh water out any of the zones such that i can "flush" them without dumping the res or what ever.

anyway heres some more shots.







heres the irrigation emmiters im useing... they are netafim spray stakes. 3gpm they spray real wide and cover pretty much the whole container.... 1 per 10 gallon container... w.e








feel free to ask anything, ill help explain anything i can

edit: redundant photo. deleted another so they all fit...

edit: moved some photos to another post.

Nice setup. A tinkerer after my own heart.

I'm working on something very similar, except that my fresh water source is a rainwater capture tank. I just bought a Dosatron fertilizer injector yesterday on eBay for $50(!) - I'm going to use that as part of a system to automatically fill a 100 gallon nutrient reservoir.

My next step is to add an automated pH monitoring system. What I'm thinking about is to have the system automatically top off the nutrient reservoir say every two days. Each night the pH monitoring process would run, and use peristaltic pumps to add acidic or base solutions to bring the nutrient solution to a specified level. The off-the-shelf systems I've found are too expensive and too turn-key - I'd like to find a wifi-based pH sensor I could integrate with a script-based home automation protocol to control the peristaltic pumps. Maybe something like Ubiquity Networks mFi (http://www.ubnt.com/mfi), or Belkin's WeMo.

Any thoughts? Have you tried something similar?

i have 0 experience with "industrial automation and control systems", that's a good piece of why im interested in this. i figure it will give me a good chance to learn plc programming and basic process control schemes. but because that has been my area of focus, i have not spent any time at all considering codeing something like a PC based control system. i find industrial scale processes to be fascinating... moveing concentrated acid through flourinated plastic pipes through electrically actuated ball valves through flow meters into big ass reaction vessles that are then temperature and pressure controlled... etc etc

ultimately i want my setup to run on its own little island... with nothing but water and power fed into it. ultimately this will include a PLC and hopefully a way to log all the analogue outputs form my EC and PH controllers such that i can pull that data out via USB or over ethernet. however that aspect of this project is way off. as you can see im just starting to tinker with the ph controller. while it does what its supposed to do, there are several minor problems that ill go into at some time when i get a chance to update this thread.

im not sure why you would want the PH sensor to be WIFI based, i can only assume you want to be able to transmit the data the ph sensor is reading to your home PC over wifi. you have to keep in mind that most if not all ph sensors that are designed for constant monitoing of process water are designed for industrial control systems. they are not designed to be user friendly or to be easily integrated into a router or anything like that. the sensor i use is a very very expensive sensor that uses a double junction electrode with an integrated thermocouple. you need a ph sensor WITH a thermo couple because outdoors... your process water will be fluctuating severely... by as much as 10... even 15c a day. a thermo couple allows you to temperature compensate for that fluctuation wich ends up being like as much as .1 or .2.

imo you shouldnt bother trying to use a 'cheep' ph sensor, focus on finding a good sensor made by an instrumentation company for a good price... not something gimmicky that can transmit over wifi or something wierd like that. keep in mind that many many sensors are just re branded from various OEM's... rosemount analytical makes very good sensors. there accuglass line is very popular and on ebay alot. expect to pay 200 one in good condition tho. the GLI sensors are made by someone i forget but they are very good as well, with replaceable salt briges and Ag/Na buffers... yokogawa makes good sensors... id stay away from lab style sensors, they are not typically made for constant immersion and measurement. it might be good to tinker with, but for a real good perminate solution you should get what i would call a 'real' ph sensor. you might also look at the sensors they make for pools... im suspecious of their quality... but apparently many people control chlorine generators useing these PH and ORP sensors very successfully. they are fairly cheap.

none of this means you need some industrial type ph transmitter or analyzer or anything tho. i would say to look into an arduino. i know that there are many many many resourses out there and communities that will help you out. im 100% positive you can find a very cheep way to get an arduino to communicate with a PC over wifi. however im not real sure how you would interface the ph sensor with the arduino. there are a couple people that make arduino stamps that handle BNC type inputs from conventional lab type sensors... however BNC connectors are only for 2 wire type sensors. they cannot handle a more sophisticated sensor like the gli differential sensor i use, so i dont know how that would work. arduinos are remarkable little electronics. with the right codeing it can handle what you are doing easily, at some point i want to tinker with them, but just not at the moment.

id not recommend that you use a pulsation to fill anyting at all. they are chemical dosing pumps meant for high pressure systems such as injecting chlorine into a pressurized pipe. i have a few pulsatron c's that go up to 100psi... they are remarkable pumps, but only good for 50 gallons of flow a day. peristaltic pumps work fine for dosing acids as long as they are using tubing rated for what ever chemical you are working with. remember to calibrate them with a stopwatch and a graduated cylinder tho. remember that in a process like ph correction you have several variables that you need to take into accound... like hysterisis, pulse modulation, PID loops... on delay off delay, over run timers, alarm relays, deadband width, output holding... flow sensors etc etc. its all very complicated, but very rewarding and interesting. id suggest reading heavily before spending money because codeing it all into an arduino seems like a huge job.

heres a free book ive been looking at. found it on some random youtube video

http://www.scribd.com/doc/75598467/Lessons-in-Industrial-Instrumentation-T-R-Kuphaldt-1v20

I'm looking at arduino, While interesting, and I think would work, pH monitoring is the only thing I would use it for (I think), so it seems like there would be a simpler solution. I'm looking for a wifi solution because there are an increasing number of wifi-based home automation / building automation products coming out, and this seems to me to be the least expensive and most flexible way to create an automated hydroponic system. The pH sensor wouldn't have to be wifi, but it eliminate cabling issues if it were. All I really need is a computer-readable, continuous monitoring pH probe.

So for example I could have a script (or series of scripts) running once an hour that reads the current nutrient solution pH, writes this to a log, then runs either the acid or base pump for say 10 seconds (or not at all) based on the pH reading. This assumes I can control the pumps via a wifi switched power plug (i.e Ubiquity's mFi or Belkin's WeMo).

The flow rate through the Dosatron should be adequate - I'm planning to get that set up end of next week so we'll find out.

i moved this from the OP due to image number constraints...

here is the bench setup im useing to test my equipment, its hard to see whats going on because of the clutter so let me explain. there are several parts here, the ph controller, a Hach GLI 53... the blue grey unit you see in the back to the right. this unit monitors the PH through the sensor you see standing upright. when the unit determines that the PH is too high, it triggers the chemical pump. the chemical pump is simply a little positive displacement bellows pump. the little plastic corrigated thing you see there is simply squeezed down which displaces what is inside it... then as it opens up, it draws more fluid inside. of coarse the pump has some check valves up top... otherwise nothing would work. this pump pushes acid into the bucket you see below which is intern mixed by the pump and this mixture is again sent back up the pvc asembly to the sensor.

a note on the assembly. i built this thing from scrap PVC so its far from optimal. its simply a very small 2gpm pump, and a flow meter and a ball valve. the ballvalve acts as s bypass in order to force more or less water into the flow cell.
im going to have to build another at some point because i need to adress issues im having regarding traped air around the ph sensor. this traped air prevents he meter from reading correctly, so im going to tinker with some pvc and see if i cant build a simple bleeder mechanism.










ph sensor...

LeeRoy said:

I'm looking at arduino, While interesting, and I think would work, pH monitoring is the only thing I would use it for (I think), so it seems like there would be a simpler solution. I'm looking for a wifi solution because there are an increasing number of wifi-based home automation / building automation products coming out, and this seems to me to be the least expensive and most flexible way to create an automated hydroponic system. The pH sensor wouldn't have to be wifi, but it eliminate cabling issues if it were. All I really need is a computer-readable, continuous monitoring pH probe.

So for example I could have a script (or series of scripts) running once an hour that reads the current nutrient solution pH, writes this to a log, then runs either the acid or base pump for say 10 seconds (or not at all) based on the pH reading. This assumes I can control the pumps via a wifi switched power plug (i.e Ubiquity's mFi or Belkin's WeMo).

The flow rate through the Dosatron should be adequate - I'm planning to get that set up end of next week so we'll find out.

Click to expand...

oh a DOSATRON... sorry. i was thinking about the pulsatron solenoid dosing pumps. sorry. yea dosatrons are cool as hell. but dont you need 2 for an A&B fertilizer dose?

if there is a simpler solution, then i dont know if it. sorry.
the arduino is very powerfull and very cheep. some are only like 30 bucks. thats a drop in the bucked compared to good PH sensor. a brand new GLI probe is over 900 dollers.
it sounds like what you want is a PH transmitter that uses WIFI. the problem is almost all analogue instruments use control systems based on 4-20ma or 0-10v circuits to relay information. so for example your ph sensor would be connected to the transmitter, the transmitter with all its fancy software and circuitry determines what the ph is, then sends it as a 4-20ma linear signal to your PLC or computer system.

it sounds like what you want would instead of of useing an analog loop, would transmit a WiFi signal using some sort of easy to use protocol. im sorry but i just dont know of anything, and or enough about those kinds of systems. again however i would point you towards the arduino communities, im sure if you asked some of the brilliant folks that 'hack' the arduino to do all kinds of cool crap they can do you can get a far far far better answer. im just a know nothing noob at this stuff.

Dang i knew some day i would find out who built the Star Trek Enterprise J/K ... All i can say is wow that is such a cool set up.

finally got my set of cheapo irrigation solenoids in the mail... i should be able to finish up the distribution end of things pretty soon. i have three exams next week so ... it might be a while before i can dig into the EC and PH controller. i have it all straight i just need to sit down and bench test it all... then all the dreadful electrical work can start in earnest.

once i get the rudiments worked out im going to concentrate on moving all the automation away from the individual controllers and into a PLC system. alot of learning before then tho.

its hilarious that i thought i would be able to work on this every weekend. between school and work, this has been impossible until last weekend.

heres where we are. i got the solenoids installed and wired.



finally finished plumbing my rock wool slabs.growth is phenomenal with these things.



check out this triple 4 plant. this stem is massive at only 6 weeks.



heres the first fruits. i pinched the first 2 nods and the first split. i plan on setting only one on each stem for now, well just see which one is the runt. eventually id like to set 6 on both stems when the plant is farther along.





potted up one of my 10 gallon bih's into a "35 gallon" container. its actually like 50+ gallons... idk why they bother to call it 35. it took like 10 homer buckets full of media + the old 10 gallon container. i pruned the plant way back as it was just too messy.



swaped the 3.2gph sprayer for a dual area 6.6gph sprayer.



ive gotten some more work done on the sensor assembly. ill post photos in a few days.

heres where i am with the sensor assembly. you will notice the flow switch after the PH sensor tee. it will close contacts at about .5gpm. the shuttle inside the sensor that moves according to flow is chattering... im not sure if the flow is turbulent coming out of the tee, or if i just need to increase the flow...either way i dont want the thing wearing out or acting funky when i have my expensive sensors hooked up, ill have to work that bit out. the sensor will act as a check in case the pump fails, or clogs... this will hopefully prevent the system from emptying the fertilizer/acid tanks.



here is the conductivity sensor. its a rose mount sensor with a .5 constant.



ive got a bunch of these sensors. they come in various geometries the high conductivity high k constant models tend to be cheaper then the lower constant cells. .1k is the lowest you can go with fertilizers.



heres the controller. it will take the sensor input and compare it to what ever set points i set. the thing is amazingly complex for what im useing it for, its way overkill.



and finally i just got my PLC in the mail. this thing was originally meant to control a fire suppression pump. im going to re program it to control my ec/ph analyzers.



the bit im interested in is the black box up top. the interface on the front of the panel i may or may not use immediately... depends on how hard it is to program. like i said im clueless about PLC's. gonna have to learn!