Indigo's Fertilizer Autodosing System (56K)

[imeridian]

There aren't that many examples of peristaltic pump dosing, so here's how I set mine up.



Here you see some emptied out peroxide bottles, holes drilled in the caps for the dosing line. The inside is standard LDPE RO line, connected to a "hose connector" which bridges onto the Tygon lab tubing. The taller bottle is 1L whereas the smaller micro and macro bottles are 500ml.



These are APT Instruments peristaltic pumps, the "topoff" pump is an SP-200 that runs at 15ml per minute and the other two are the SP-100 running at .5ml per minute. The ID of the norprene hose is 1/8th whereas the ID of my lab tubing is 3/16, so you see another set of bridging here, this time using reducing connectors. I chose slow pumps to increase dosing accuracy. I also can then have my solutions at full strength in the case of Flourish, or at the limit of soluability for the macros. The macro line is stained blue from the single drop of Methylene Blue added to the mixture used to help inhibit fungal growth.



This is basically a work in progress. If I were to do it again I'd have separate lines into the CO2 reactor, but this setup does work fine. The line at the top is the "topoff" line that runs through flushing the line of micros and macros. The checkvalves are the "liquid/gas" from US Plastics, all other fittings and tubings are also from US Plastics.

Right now I have the dosing pumps set that the macro pump runs, the topoff runs to flush the system, the micro pump runs, and then the topoff pump runs again to flush the system. I've had it setup on the standard EI 3X weekly settings, but recently switching to dosing daily.

The biggest thorn in my side has been the pathetic quality Grasslin timers I've been using to regulate all of this. They seem to reset themselves at will despite replacing them through Drs Foster & Smith. I will likely just purchase an Aquacontroller Jr to control the pumps and all other items that need timers.

The topoff didn't quite work as originally planned, I have a float switch, but it was so big and ugly and prone to slipping, so I never implemented it. It also didn't occur to me at the time that to topoff my daily evaporation that it would take 4 hours with a 15ml per minute pump -- in my defense I bought the pump before I had the aquarium running. In any case, eventually I will actually make it a topoff pump, but for now it's more of a "multi purpose doser." Right now it's dosing plain water to flush, but in the past I have used it to administer excel dosing, extra potassium, and the staining of the tubing is from dosing a light "gh builder" solution. I like having that versatility. In the near future I will be setting up a 5 gallon bucket to do more of a real topoff though, the pumps are basically silent so running for a few hours to slowly topoff isn't really a problem.

Questions are welcome (so are constructive criticisms).

[Sponsors]

[gmccreedy]

Very nice setup indeed sir. I have to agree with the two separate lines into the reactor for dosing. I myself have not setup an autodosing method yet, but will in the next few months once I figure out what method of dosing works for me.

With regards to the AC jr, ironically enough, mine just came in the mail for me. I honestly went this route for the reasoning you have, I hate the stupid timers. I have had two timers burn out on me in the last 6 months and luckily it was not on my Fill solenoid on my auto water changer or that could have gotten real ugly real fast (considering that the one timer actually froze with power on...figure that one out).

Well done though.

[lescarpentier]

Judging by the loneliness of this thread,I think that most people,like me,are scratching their heads in bewilderment.However,I am favorably impressed,and know that eventually I will be implementing a system such as yours.Thank you for taking the time to share this with us,and for the honest,and frank assessment of your efforts.This is remarkable!

Now for my questions.
How much does this system cost to set up?
Are there any kind of safeguards to prevent over fertilization,other than continual monitoring?

I look forward to any periodic updates.

Once again,thanks.

[imeridian]

There's a lot more risk of under fertilizing than over, really. The timer problem mentioned earlier has resulted a couple of times in no fertilization happening that day -- which is a big reason for my switch to daily dosing of both micros and macros. If I miss half a dose it isn't so bad. The pumps won't allow any fluids through unless they're powered on.

As for cost... a lot? Each pump is roughly $80, tubing is $.40 a foot, though I'm sure one could use regular inexpensive stuff instead. Figure in probably $10-15 for fittings, check valves, and miscellaneous stuff, and a ridiculous $20 for each timer (and, really, I'm so disgusted with these timers). I've never added it up... and, well, I won't either.

Heh, threads I start are usually lonely... *shrug*

I've been thinking of setting up a sort of 'mini reactor' inline after the main CO2 reactor, just a series of injector ports on 3/4" pvc. It'll cost a lot less than redoing my reactor, and the lab tubing just isn't sturdy enough to be drawn directly through the pipe wall like tygothane or norprene is. I stacked 4 tees together for 2" pvc the other day at Lowes and it's a bit too huge for my liking. The 2" pvc would be also upgrading my CO2 reactor, as the 1.5" appears to not be quite large enough, still get micro bubbles. I don't mind the bubbles so much, but I figured if I was redoing the reactor for one reason, I might as well redo it for another while I was at it.

When it really comes down to it though, apart from the timer problem and realizing I could improve the actual injection, I'm quite satisfied with how this has been working for me. Consistency has always been a big problem for me when it comes to dosing. Since I've switched to autodosing my plant growth has improved remarkably.

Oh, and thanks Glenn, especially for sharing my pain (lol) over bad timers.

[epicfish]

Nice work!

[EdTheEdge]

A true hobbyist.... I salute you!

[gmccreedy]

I am curious which timers you are having problems with and if they are the same as mine.

Did you use the H202 bottles for any particular reason or just had them laying around?

What kind of volume are you dosing and what are your turnover rates from your solutions? (ie how many doses per bottle)

[imeridian]

They're the grasslin digital timers from DFS.

I used H202 bottles intentionally. They're HDPE, so stable over the long term, and opaque so as to prevent any long term light damage. It was just easier to pop over to walmart, pick them up, dump the h2o2, than to order appropriate bottles.

The macro bottle holds approximately eight weeks of solution. With the daily dosing, the pumps run between 15 and 20 minutes (micro/macro), delivering 7-10ml of solution.

I'm basically using the same solution I used to mix up and dose using a 25ml graduated cylinder manually, and I know it's good for that long (except the one time I left it mixed in the erlenmeyer flask on my desk -- I grew some very interesting things in it that time). The Flourish Comprehensive is at 100%, no dilution, so it's more a matter of just pouring it from the 2L jug into the 500ml bottle.

The 1L bottle is changed weekly, as I dose 150ml per day over the week of 'topoff' (aka line flush).

I did recently cut down from dosing 25ml of macro 3X weekly to dosing the 10ml everyday. That extended my solution longevity to 8 weeks from about 6.5. Now, since none of that really means a lot, here's what my macro mix is:

Macro Mixture: 500ml total volume with RODI Water
92g KNO3, 8g KH2PO4, 25g K2SO4

25ml = 9.94ppm N, 0.98ppm P, 8.65ppm K

My macro mix is also sort of a work in progress, I've only recently added the extra K.

[gmccreedy]

75 gallon tank?

So your flush line is simply to flush out the dosed mixture daily? Now, do you account for the excess "stuff" left in the tubing that is flushed into the tank? Did you calculate that somehow (ie the volume of ferts that is in the line once you dosing pump stops)

interesting concept with the H202 bottles. Never thought of using them.

[imeridian]

Yes, 75 gallon tank.

There really isn't any 'excess' to account for. The outflow line from the pump stays 100% full, in addition to the inflow line to the pump. When the pump is on, it's basically dripping out of the check valve right into the 'flow line system' with all the connections. Well, there is that tiny bit of tubing that connects the checkvalve to the 'flow line' but it's so tiny (and hidden with electrical tape in the photo) that I don't worry about it.

The flush line is, yes, just that, there is a short space there where the two fluids may meet, I use the 'topoff' pump to flush that. I used to have the pumps (and all connections) on the other side of the stand, thus there was a lot more need to flush the line (since it was 4' long), now it's much less important and part of the reason for the pump move too.

I think once I get a larger volume container setup for the topoff that I'll run that pump for the entire period the fert pumps are running. It's interesting to watch the fert pumps run, because it just basically squirts out little droplets in the line, spaced with a vacuum "bubble."

Those piece of crap grasslin timers reset themselves again sometime today, just the two fert pumps, yesterday it was just the macro pump. I'll need to do something about the timer situation immediately, it can't wait for the AC jr. Well, maybe I'll order it within the week instead of "eventually" as planned. I wish I knew why the timers were resetting randomly.

[Wasserpest]

I have a wild mixture of electronic timers and they are all working extremely well. There are different GE timers, Intermatic, but no Grasslin. Do you have power outages that make those timers reset?

I am to cheap for the AquaController, but I am wondering if an Irrigation Timer (~$20) could be tweaked to control pumps. Maybe the 12V output could control relays that switch the pumps. The model I am thinking of has 4 zones -- one could run the first zone (macros) for a few minutes, then the second zone (main lights) for 10 hours, then the third zone (moonlights) for two hours, then the fourth zone (micros) for a minute. Hmmm... there is an idea.

I tweaked a little delay timer circuit to switch my pumps in the second instead of minute range, and it can be connected to the light timer or to one of those cheap mechanical timer things. The AC is definitely nicer though.

The drop of methylene blue is a great idea, need to try that.

Instead of topping off via the expensive peristaltic pump, you could probably get a $15 waterpump and use that one to top off in a minute or what.

[imeridian]

It isn't power outages or any other surges that I'm aware of. The UPS on my workstation and file server will send an email as the result of any power event. Perhaps it's excess EMI from all the cords under the stand, it's very random. The one pump would reset everytime I pressed the manual 'bypass' button, I exchanged that one. The other two I've had too long to do anything about, other than just replace with something else. They have NiMH rechargeable batteries inside that protect against power outages, supposedly, I can unplug the timer and it keeps the time; that's how I program them.

Yes, the topoff pump is sort of... one of my boneheaded choices. I've thought of switching it to something else, but I'm not really sure what. It all stemmed from my original idea of using the float switch, which triggered the relay, etc, and it'll just topoff slow over the course of the day as needed. The float switch idea fizzled, so... I've made do without any real automatic topoff.

Yes, the price of the AC Jr is a real sticking point for me. I look at it how I look at everything else though... if it'll solve my problem, it'll be worth it. I don't know how many other brands of timers and such I'll need to go through until I find a workable solution.

The Methylene blue idea comes from Ed over at APC, I'm sure 'weird things growing' is much greater a problem with the seriously diluted PPS solutions.

Is this the sort of irrigation timer you were referring to?

[plantbrain]

Originally Posted by indiboi