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Miracle Grow Liquafeed Mod

Scuba_Steve

Scuba_Steve

I bought 2 venturi injectors to make my own 2 part fertilizer injection system. Unfortunately, I could not get them to produce suction. I think my flow rate through drip emitters was not high enough.

So instead I bought a Miracle Grow Liquafeed system.

liquafeed_FAQ1.png


I found out that I could grip the dosing mechanism on the feed bottle with pliers and pull it off so I could refill them.

My question is on fertilizer concentration.

I am using the Howard resh recommendations for pepper fertilization, and mixing everything myself.

I am alternating between a bottle of calcium nitrate, and a bottle of everything else because your not suppose to mix calcium nitrate with anything containing sulfur.

The bottle on the feeder is 16 oz, and empties completely in 1 watering. I am watering every other day for 2 hours through 1gph emitters. I have about 150 emitters hooked up to the system.

So after you take in all this info, what concentration should I mix my nutrients to go into the bottle?

To summarize, I'm putting down about 300 gallons every other day, and adding 16 oz of fertilizer.

1200:1 would give me full strength, but that seems extremely excessive, especially because that concentration is actually designed for a hydroponic reservoir, not soil where it will accumulate over time. I am thinking maybe 50:1, or even less...

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you simply need to determine the dose rate assuming the dose rate is constant.
 
once you determine the dose rate( assuming its a fixed rate). you taylor your concentration to that dose rate such that the end solution arrives at your desired concentration.
 
so... say it doses at 1:100, or 1 ml of fertilizer solution for every 100 ml of tap water. in this case you need to mix the stock tank solution at 100:1(100 times the target concentration), or the exact inverse of the dose rate.
 
so do a little experiment here... collect a volume of water from your irrigation system and coorelate this volume with the volume lost from your stock solution bottle. make sure that the flow rate of your experiment matches, or closely matches that of the flow rate of your drip emitters. reason beaing that venturies vary mostly linearly with the velocity of the water flowing across the oriface.
 
the problem with fixed flow rate dosing is when you cannot formulate a stock solution high enough with the chemicals you like to use. you may find that the dose rate is so high that you will get precipitation or clouding from one or more of your stock tanks... but only experimentation will tell you for sure.
 
what ever concentration you arrive at, make sure to jar test it... put it in the fridge over night and examine it closely for sedimentation or turbidity.
 
queequeg152 said:
you simply need to determine the dose rate assuming the dose rate is constant.
 
once you determine the dose rate( assuming its a fixed rate). you taylor your concentration to that dose rate such that the end solution arrives at your desired concentration.
 
so... say it doses at 1:100, or 1 ml of fertilizer solution for every 100 ml of tap water. in this case you need to mix the stock tank solution at 100:1(100 times the target concentration), or the exact inverse of the dose rate.
 
so do a little experiment here... collect a volume of water from your irrigation system and coorelate this volume with the volume lost from your stock solution bottle. make sure that the flow rate of your experiment matches, or closely matches that of the flow rate of your drip emitters. reason beaing that venturies vary mostly linearly with the velocity of the water flowing across the oriface.
 
the problem with fixed flow rate dosing is when you cannot formulate a stock solution high enough with the chemicals you like to use. you may find that the dose rate is so high that you will get precipitation or clouding from one or more of your stock tanks... but only experimentation will tell you for sure.
 
what ever concentration you arrive at, make sure to jar test it... put it in the fridge over night and examine it closely for sedimentation or turbidity.
Click to expand...
Gotcha. According to the FAQ on the miracle grow site, the dose rate is 325:1.

I guess what I am really asking, is what final concentration should I be putting down into the soil?

1:1 seems highly excessive to me because, again, this is designed for hydroponics. In dirt, this will accumulate over time.

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Every other day seems a bit excessive though I could be wrong with your climate. My first year with peppers I watered every morning for 20 minutes with my drip system. Last year I think I ran it twice all summer. 
 
I am row gardening, and my rows dry out very quickly. Lots of pine fines and perlite in the soil mix i used for them. Plus Southern GA has pretty intense heat. I am sure I will lessen the watering a bit when the plants get larger and have root structures larger than the rows. The actual ground will stay wet quite a bit longer I am sure.

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Scuba_Steve said:
Gotcha. According to the FAQ on the miracle grow site, the dose rate is 325:1.

I guess what I am really asking, is what final concentration should I be putting down into the soil?

1:1 seems highly excessive to me because, again, this is designed for hydroponics. In dirt, this will accumulate over time.

Sent from my LGLS991 using Tapatalk
Click to expand...
 
1 is what ever your target solution is.
 
use what ever concentration you like. without a soil analysis, its impossible to say what exactly you should be fertigating at, but i would cut out most of the phosphate in the resh profile at the very least.
 
this is a simple mass balance relationship.
 
let c1 = target solution, c2 = tap water solution, c3= stock tank solution. 
 
let c=m/v; where m = mass in miligrams, and v = liters.
 
given you know all but one variable, its down to elementary algebra to solve for the needed concentaion. 
 
you can solve it as a sort of differential equation if you wan the 2nd order relationship... variation in the needed concentartion with respect to the total flow rate. 
 
let c3 = x / ((1/325)*y;
 
where x is unknown stock tank conventration, and y is total flow rate. 
 
let c2 = tap water concentration / (324/325)*y
 
and let c1 = target concentration / y
thing is though... venturies are almost never ever constant across all flow rates/velocities... not unless you use a flow meter and means to adjust the dosing rate.( this is how big huge fertigation rigs sometimes work.)
 
I am 99% sure this does not use a venturi. It starts clicking loudly when it is dosing. I read somewhere before that it uses some type of internal pump, but am not 100% on this.

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Scuba_Steve said:
I am 99% sure this does not use a venturi. It starts clicking loudly when it is dosing. I read somewhere before that it uses some type of internal pump, but am not 100% on this.

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Click to expand...
VERY interesting... this thing operates like a dosatron. its just not adjustable like a dosatron...
interesting. i might get one of these to evaluate... what do they cost?
 
$15, and they are adjustable. There is a water/feed lever. It clicks at a slower rate when it is closer to the water setting.

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nice... about 300 bucks less than a dosatron lol.

i think that valve is just a bypass though. the dosatrons are adjusted by varying the length of the stroke. this is better because it keeps the dose per unit of volume constant at all flow rates. when you bypass using a ball valve like that... the ratio bypassed varies with the velocity of the water. you dont have perfect proportional dosing at all flow rates.

its not perfect, but for 15 bucks? its quite impressive. where did you get it at? i cant find it on amazon.
 
Also, I expect the bottle to mess up after I have refilled it a few/20x times.  It is very difficult to pull out the valve, and it seems like hard brittle plastic.  But when it does, ill just buy a pack of refills and continue usage...
 
by chance...are the threads standard soda bottle threads?

those bottles are way way way way way too small. id need somethign like a 5 gallon bucket.
 
I cant view the pics without making an account on that forum = (.
 
but it sounds like people are ahead of me on this thing... 10 bucks for a real proportional dosing unit? i serously think they could be loosing money on this unit in the assumption that they will make money on the bottles.
 
i was thinking along the lines of filling the threaded outlet with an epoxy resin and cutting new threads into the epoxy.... id have to be able to ge the housing off of the thing though. idk if thats possible.  i have a set of NPT taps though id like to give this mod a try when i get some time.
 
how does this thing vent the bottles btw? the bottles look sealed?
thanks for the thread link btw.
 
ok i see what hes doing...
 
do you by chance know how this thing equalizes the pressure inside the bottles?
 
do the bottles have holes to let air in, or does the unit pump air into the bottle?
 
The bottles don't have holes, I think it equalizes with the pumping action, check out his vid
https://www.youtube.com/watch?v=owe4N4RfWUw&feature=youtu.be
 
queequeg152 said:
by chance...are the threads standard soda bottle threads?

those bottles are way way way way way too small. id need somethign like a 5 gallon bucket.
Click to expand...
 
No the threads are far from anything standardized.  Very large gaped threads.  Trust me, that was my original thought before I bought this unit!
Rather than do the above idea, cutting the threads off and gluing them on something else, I think you would have an easier time attaching a fitting of some sort on to the bottle itself.
 
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