Mix your own hydro nutes from chemical salts!
Posted 23 October 2007 - 12:35 PM
Basically the idea is to save boatloads of money and have more precise control over your nutrient solution by mixing up carefully measured amounts of chemical salts into concentrated "stocks" that are then added to your rez. This sounds complicated, but it's really not so hard. I went from total cluelessness to a working nutrient solution in less than two weeks, including waiting around for the chemicals to ship. Why would you want to do this? Well, if you're committed to hydroponic growing, you've probably noticed how much lighter your wallet gets whenever it's time to re-up on nutes. I spent $175 on chemicals, and now I've got enough raw materials to mix up about 4000 gallons of nutrient solution, which, with my almost-finished setup (recirculating DWC - 8 five gallon buckets) means that I can flush my system and replace with fresh nutes every week for the next three years. For $175! Financials aside, you now know exactly how much of each element is being added to your rez, down to the ppm and can tweak it if needed.
Here's how it works. Your plants need the following elements to live:
Macro Elemets (need alot):
Nitrogen (N), Phosphorous (P), Potassium (K), Magnesium (Mg) Calcium (Ca)
Micro Elements (need trace amounts):
Boron, Copper, Iron, Zinc, Manganese, Molybendum, Chlorine
So, where do these elements come from? The internet, of course! Well, if you are lucky enough to be able to source these locally, do it, shipping sucks. These are the chemicals you'll need:
Potassium Nitrate (could substitute Potassium Sulfate)
Magnesium Sulfate (Epsom Salts)
and the micros:
You can get pretty much all of these things from www.hydrogardens.com but the Calcium Nitrate and Monopotassium Phosphate are cheaper from Hydroponic System Supply HID Lighting Hydroponic Equipment & Hydroponic Light - Atlantis Hydroponics and the epsom salts are like 30 cents a pound at any drugstore. Keep in mind that shipping is a major cost factor and shop around a bit. I found the calcium nitrate at a local garden center. The micros you'll probably have to order, but the total weight is only five pounds. The Monopotassium phosphate (MKP from now on...) is also available in 500mg capsules from the drugstore as K-Phos, but is prohibitively expensive in this form unless you're making a very small amount. Also, I got my Potassium Nitrate from ebay, 10 pounds for $30, after shipping. People use it to make fireworks.
So, now we need to find the right amount of each salt to add. Of course this depends on what nutrient profile we're trying to achieve. Many, many different hydroponic nutrient profiles exist. If you follow that ICMag link above, you'll find a post by sproutco where he shows how to replicate the Johnson's formula. That post is really informative and helpful, btw. I'd recommend reading it through a few times. After reading through the really helpful and informative CannaStats nutrient profile page - CannaStats - Nutrient Profiles for Cannabis - I decided to shoot for a profile of 100N - 100P - 200K - 60MG - the ideal around which the popular Lucas formula is patterned (Lucas is 8ml GH Micro to 16 ml GH Bloom). This formula works for all stages of growth, and lots of people have experience with using the GH Lucas formula, so their experience will hopefully be relevant. An incredibly useful tool for calculating the amount of salts needed is the saltmix3 excell spreadsheet available here: CannaStats - Download Page
The spreadsheet allows you to basically just plug in numbers and tweak them until you get it right. Here's how I figured mine out. Since we only have one phosphorous source (the MKP) it's the easiest to calculate. I just kept putting numbers in the box for monopotassium phosphate until I came up with 100 ppm phosphorous. This ended up being 1.7 grams/gallon. This also adds 126 PPM potassium, so we're nearly there on the K. We just need to add 0.7 grams potassium nitrate, which brings K up to 194 (close enough for me) and adds 24 ppm N. To get the rest of the N, we use 1.9 grams calcium nitrate, which adds 77 ppm N and 110 ppm calcium. For magnesium, we use epsom salts. The spreadsheet has two kinds of magnesium sulfate. For drugstore epsom salts, use the magnesium sulfate heptahydrate. This will give the correct value. For agricultural epsom salts, use the plain magnesium sulfate. I've got drugstore salts, so I needed 2.5 grams epsom to give me 64 ppm Mg, as well as 84ppm sulfur.
You don't need the spreadsheet to do this; you could just do the math as per sproutco's post in the icmag link. It's just easier this way, and less room for calculation error. The micros you do need to do some math for, but it's a lot simpler than the macro elements, since we're only adding one element at a time, whereas with macros, we need to figure out how much N we're adding with our K when we add potassium nitrate, for example. So, check it. For the micro elements, you need to know two things, how much you want, and how much of each raw chemical you need to get there. Here's the micro element profile I chose (it's on the first page of that icmag thread, the modified Steiner's):
Note that this is in parts-per-million (ppm). So I want .3 ppm boron. I have boric acid that's 17% boron. If you multiply the amount you need in ppms (0.3) by the inverse of 17% (1 divided by 0.17 - your computer's calculator probably has an inverse key - 1/x - but you might have to set it for "scientific mode") you get the milligrams/liter of boric acid to use. Multiply this by 3.8 to get the milligrams per gallon (there's 3.8 liters in a gallon). For me, that's 1.76mg per liter == 6.7 mg per gallon.
The rest of the micros are the same, the numbers are just different. In each case you find the concentration of the element within the salt (17% above), take its inverse, and multiply by the ppm level you want. That gives you mg/liter, multiply by 3.8 for mg/gallon.
Once you've done the math for each element (twice!! always double check!) you'll probably realize that weighing out such miniscule amounts of micro elements is going to be impossible. That's one reason why we make concentrated stocks of solution. The other reason is that it's a lot easier to just pour an ounce out of a bottle of stock than to mix up a bunch of salts. You can easily make enough stock in an hour to last a few months.
Damn, this post is getting long. But if you've read so far, you probably want to know about actually using all this info. Right now we know how much of each salt to mix up to get a given elemental concentration in our solution. We've done the math for 1 gallon of solution, using the saltmix spreadsheet for the macros, and a good ole calculator for the micros. Now we need to figure out how much stock we want to make, and how concentrated we want it to be. I decided that I wanted to use an ounce of stock per gallon of solution, since that's easy to remember. Since there are 128 ounces in a gallon, I take all the weights I figured out earler and multiply by 128. I can now make one gallon stocks, which can be used to make 128 gallons of solution. Here's a really important point - you MUST keep the calcium nitrate separate from the magnesium sulfate, otherwise they will precipitate in the stock jar and be useless to your plants. The way to go is to make three stocks. One has just the calcium nitrate dissolved into it. One has the MKP, potassium nitrate, and epsom salts. The third has the micros. You add an ounce from each one to get the full nutrient profile.
Making the stocks is pretty simple. Get three gallons of distilled water. Take one jug, pour about half of it into a saucepan or something and heat it on the stove. Don't need to boil it, just get it nice and hot so things will dissolve easily. Now take your half-empty jug and pour about a pint or so into another container and set it aside. This is really important, because after we dissolve the salts into the hot water, the volume will increase. If you try to pour that back into the half empty jug, there wont be enough room, since we're adding back a greater volume than we took out. While the water's heating up, weigh out 128 gallons worth of calcium nitrate (in my case 243.2 grams). Once the water's hot enough (a little steam, no boil) mix it in really well with a fork or something until everything's dissolved. I found that the calcium nitrate left a scale of some non-soluable gunk on the edge of the pot. That's cool, just scrub it out before you do the next stock. Pour your hot solution back into the jug with a funnel, then add back some of the water that you set aside earlier until the bottle is full. Now do the same for the next stock, this time using the MKP, potassium nitrate and epsom salts. The micros are a little trickier, since you're weighing out such small amounts. I found that a little piece of tin-foil set on the scale and "tared" makes a good tray for weighing out micros. The copper and molybendum are kind of tricky, since you need such tiny amounts. My recipie called for 0.12 grams sodium molybdate for 128 gallons. Sure I could just weigh out 0.1 grams and deal with it, but my scale is only accurate to the tenth, so who knows exactly what you'd get. So instead, I weighed out 1.2 grams and dissolved it in 100ml distilled water. Then I used an old (clean!) spore syringe to suck up 10ml of that solution and shot it into the jug. I did the same thing with the copper, since I only needed 0.69 grams.
And there you go. You've now got a homemade three part nutrient solution made to your own specs. You can change the nutrient profile to meet your plants needs, and once you've got it perfectly dialed, you can mix up enough stock in 5 gallon jugs to last a year at least. I'd like to point out that I am far from being an expert at this. This is my first try, and all the info I've presented I've learned from that ICMag thread and a bit of noodling around on the net. I've been using it for a few days now with good results. My momma plant really digs it at half-strength. The plants in full flower are showing deficiencies at half strenght, so I'm upping it today.
Here's a pic of the momma, four days after the switch from General Hydroponic nutes:
Also, my prep table after the mixing was done (sorry I didn't grab any pics of the mix itself):
Here's my bin full of dry nutes:
And a really crappy pic of the finished product:
Please feel free to ask questions; can't promise I'll know the answers, but maybe we can figure it out together? Like I said, I'm a newbie at this, but so far, results are really promising, and I'm really excited about it. Hope this helps someone!
Posted 23 October 2007 - 12:38 PM
Posted 26 October 2007 - 02:46 PM
Posted 26 October 2007 - 09:56 PM
Posted 27 October 2007 - 01:28 AM
here's some pics i took today of the blooming plants:
you can see the wilty leaves in these shots:
in fairness to my nutes, these plants were hurting before the switch. I let the rez drain dry and added new nutes without a fresh water flush. the bottom inch or so of water was super concentrated, and the plants burned. this was with GH nutes btw. I've got two closets going right now, the one that got flushed properly is doing much better. it's sleeping now though..
here's a shot i took before i figured out how to adjust the white balance on my cam. i think it looks neat in the orange light:
and finally, a shot of the canopy:
btw, these plants were vegged under CFLs and flowered under a 400 watt HPS. The HPS is set up on a flip-flop relay so that each of my two cabinets gets twelve hours of light.
thanks again for the interest. i'll keep posting as things develop
Posted 27 October 2007 - 08:54 AM
Posted 27 October 2007 - 06:22 PM
Posted 27 October 2007 - 06:26 PM
Posted 02 November 2007 - 11:45 PM
It's an eight bucket recirculating DWC system, lit by a thousand watt light on a flip flop timer, so each half of the room gets twelve hours of light per day. For flowering, I'm just going to split the room into two, and each room will get 12/12. I planted the clones yesterday, and haven't added any nutes yet. I'll probably do so in a few days, once they've grown some fresh roots and adjusted to the new environment. Please let me know what you think! peace
Posted 16 November 2007 - 09:44 AM
-- Macro elements --
calcium nitrate: 1.9 grams
epsom salts: 2.5 grams
monopotassium phosphate: 1.7 grams
potassium nitrate: 0.7 grams
-- Micro elements --
iron chelate (13% Fe): 87.69 mg
boric acid (17% B): 6.7 mg
manganese chelate (13% Mn): 29.23 mg
sodium molybdate (39.6% Mo): 0.96 mg
zinc chelate (14% Zn): 10.85 mg
copper chelate (14% Cu): 5.42 mg
For my 1 gallon stocks, which I dilute one ounce to the gallon, I just multiply everything by 128 (ounces in a gallon). So for 128 gallons of solution in three 1 gallon stock jugs:
243.2 grams calcium nitrate
320 grams epsom salts
217.6 grams monopotassium phosphate
89.6 grams potassium nitrate
11.22 grams iron chelate
0.85 grams boric acid
3.74 grams manganese chelate
0.12 grams sodium molybdate
1.38 grams zinc chelate
0.69 grams copper chelate
1.3 grams table salt - optional - for 2 ppm chlorine
This gives you a nutrient solution with the following profile:
nitrogen: 101 ppm
potassium: 100 ppm
phosphorus: 194 ppm
calcium: 110 ppm
magnesium: 64 ppm
sulfur: 84 ppm
boron: 0.3 ppm
copper: 0.2 ppm
iron: 3 ppm
manganese: 1 ppm
molybendum: .1 ppm
zinc: 0.4 ppm
also attached is the saltmix3 spreadsheat from the Canna Site, filled out with the values for my macro nutrients. it's in M$ excell format inside a zip archive. Feel free to use this recipe as is, or as a basis for further experimentation. props for the spreadsheet go to pH of canna site.