# Finally got some Master Blend and did the math



## TxGypsy (Nov 23, 2006)

I finally got around to going to Morgan County Seeds and bought some Master Blend to make the fertilizer mixture that MHP gardener speaks so highly of. I changed all my tomatoes and peppers over to it today and cannot wait to see the results. They should come out of vegetative growth mode(the nutrients I had them on promoted vegetative growth) and start blooming and producing more.

MHP figures his mixture out in grams. I don't have a scale, so I converted it over to teaspoons. Probably not as precise, but pretty close. When I realized just how little of each component it was going to take to mix up the nutrients in a 5 gallon bucket (I'm doing a replenishing Kratky method), I had to do the math!

Master Blend (25 pounds) sells for $37. Per 5 gallon bucket you use 12 grams. There are 453.59 grams per pound. Divide that out and you can make up 38 buckets per pound. There are 25 pounds per bag, so multiply that times 38 and that means that you can make 950 buckets worth of nutrient solution from a 25 pound bag. That works out to .04 cents per 5 gallon bucket of nutrient solution.

The 2nd component of this is Calcium Nitrate. I can get 50 pounds of Calcium Nitrate at the same place for $29. The formula calls for the same 12 grams per 5 gallon bucket. Using the same math, but adjusting for it being a 50 pound bag rather than 25 pounds, I came up with it working out to around .02 cents per 5 gallon bucket.

The 3rd component is epsom salts. 6 grams per 5 gallon bucket. Epsom salts are so cheap that I admit that I didn't do the math and figure that it costs an additional penny per bucket.

There was some gas involved in going to go get it but not much(used the Prius rather than the gas guzzling 4x4 beast). If you have it shipped to you there would be those expenses, but I decided to simplify and just use the purchase prices.

That equals out to .07 cents per bucket of nutrients!!! Wow! Let's suppose that I actually got the transplants started early in the spring like I'm supposed to(tomatoes, though it's good for other things) and get a full growing season worth of tomato production out of my plants. Lets suppose I use a generous 5 buckets worth of solution during the growing season. That's .35 cents. 

I was thinking of transitioning over to aquaponics, but the Kratky method of hydroponics is so easy and pretty danged cheap. I think I'll take a day off from time to time and go fishing instead. I'll have time as I won't be weeding


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## stanb999 (Jan 30, 2005)

I do suggest you get a scale. They can be had from amazon for just a few bucks. It's well worth the expense. You can easily overdue the nutrient using the spoon method. A gram in a tiny amount.

I have one like this. 
https://www.amazon.com/Ozeri-Digita...&ie=UTF8&qid=1469106987&sr=1-3&keywords=scale


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## stanb999 (Jan 30, 2005)

Yeah, the nutrient is very cheap. I agree it's so cheap that it doesn't make sense to bother with trying to do aquaponics. 

Do you have the ability to mix larger batches? It's easier to get the amounts right... For instance if your mixing 5 gallons 12 - 12 - 6. if your off a gram on the mag. your off nearly 20% which is huge. With 100 gallons you'd mix 60 grams being off a gram is less than 2%. Tho it is very forgiving.

Next thing I will explain the best I can. This is the principle reason so many fail at keeping the plants going long term. The issue with large plant feeding. This includes not just tomatoes, but peppers, eggplants, cucumbers etc.. It's a bit of a pain to do properly because of plant physiology. What happens is a healthy plant can remove all the NPK nutrient from the solution in as little as 12 hours. This can cause you to want to add more fert. to maintain the PPM. If you do you will be overfeeding the plant and cause nutrient imbalances, generally first shows up as Blossom end rot (Calcium is the slowest nutrient.) Now here is the but... But without the NPK the ph of the solution rises. This makes most of the slower to absorb micro-nutrients unavailable to the plant.

So how do you ensure your plant is getting what it needs but not too much? 
You have to figure out how much nutrient the plant needs. It would seem difficult but the info is widely available. For our purpose here we will say a large healthy tomato plant uses about 50 oz of solution a day. So weekly it will need about 350 oz or a little less than 3 gallons. Sound good? The issue is if you add a little nutrient at a time like a float valve would to a moderate sized tank the NPK will be removed and the ph will rise as noted above and exclude micro-nutrient uptake. See the problem?

Here is what I do. I add nutrient to the tank in bulk at the rate the plant uses it. Then adjust the ph to the lower end with acid so when the PH rises it's still the the ok range. The float valve adds only water. 

You will have to adjust these numbers to fit your tank size but you should get the idea... I will calculate for a 5 gallon tank holding 1 plant. 

We noted above that a plant will use 3 gallons nutrient per week. So we want to remove 3 gallons of old nutrient from the tank and add 3 gallons of fresh nutrient to the tank weekly. Adjust the ph in the tank to be around 5.5. As the plant feeds the ph will rise to around 6.5 or so keeping the nutrients available the whole time. You also wont be over feeding because the total added nutrient is correct. You will still want to change out all the water every so often to avoid building up excess nutrients. every few weeks is fine as MHPGardener suggests. Now say your tank is smaller you can add more often or if your tank is huge you can add a little less often. But you don't want the tank to be much bigger than needing refeeding every 2 weeks. Mine tanks are sized that we feed every 4 days and change the water out every 2 weeks. 


This is the reason the vast majority of vine crop growers add just a bit more than needed daily and drain the excess to waste. This is how dutch buckets work without a return to tank. This is also the method Dr Kratky actually suggests for tomatoes. His tank shape is different but still you basically just add about 60oz to a 50oz pot daily. keeping the pot fresh the whole time.


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## oneraddad (Jul 20, 2010)

Instead of measuring or weighing, get yourself a PPM meter so you get it exact.


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## stanb999 (Jan 30, 2005)

oneraddad said:


> Instead of measuring or weighing, get yourself a PPM meter so you get it exact.


I agree that they should have a meter... But use it only as a gauge. Because most people wont go and get a high quality meter that also takes temps into account. Which will run you about 2 to 3 hundred bucks. The cheap Chinese ones are just that... Cheap and inaccurate.

Then you still can't measure the individual NPK. Without it your just guessing whats missing. They do make meters that will measure these. But a full set would be very expensive. More than a thousand bucks. 

Here is a source if you wish to look into them.
https://hydro-gardens.com/product-category/growing-supplies/monitoring-equipment/page/4/


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## oneraddad (Jul 20, 2010)

I got mine after I burned my plants years ago and haven't had a problem since. It's pretty easy to get 3000PPM when you only want 1000 so it works perfect for my use.


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## TxGypsy (Nov 23, 2006)

I agree with all your points, but....this is my very first try at hydroponics. I have about 8 tomato and pepper plants in kratky buckets. I had plans to install bubbler lines, but it is too danged hot to do anything outside right now so that didn't get done. Which is unfortunate because my buckets have become mosquito nurseries!

The math is accurate because I used grams....even though I am using teaspoons for measuring at the moment. Next year once I have the greenhouse up and going I'll probably get a scale. As to overwhelming the plant with nutrients and the uptake issues you mentioned. I'll probably handle it like I do most things....observation, a bit of intuition(educated guessing) and learning what works.


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## stanb999 (Jan 30, 2005)

TxMex said:


> I agree with all your points, but....this is my very first try at hydroponics. I have about 8 tomato and pepper plants in kratky buckets. I had plans to install bubbler lines, but it is too danged hot to do anything outside right now so that didn't get done. Which is unfortunate because my buckets have become mosquito nurseries!
> 
> The math is accurate because I used grams....even though I am using teaspoons for measuring at the moment. Next year once I have the greenhouse up and going I'll probably get a scale. As to overwhelming the plant with nutrients and the uptake issues you mentioned. I'll probably handle it like I do most things....observation, a bit of intuition(educated guessing) and learning what works.


Best education is doing it.


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## TxGypsy (Nov 23, 2006)

I mostly posted this so that folks would have some idea what the nutrients cost. I always thought that it would cost a lot of money to grow plants hydroponically. It is expensive when you buy the little premixed bottles at a hydroponics store. Figuring out the cost has opened up a whole new world of possibilities for me. Other than the mosquitos(which will be fixed once I have things set up properly) this method of growing is sooo much easier than in dirt!

I've fought aggressive southern grasses in my garden all of my adult life and nothing works except lots and lots of hard work and in the end it's going to win out anyhow. It is so discouraging to put that much effort and sweat into something and end up giving up over and over. There is no weeding at all with this!

I'm honestly researching to see what all I can grow this way. I don't mind spending the money to get set up properly since it will save so much time on gardening chores. I just moved into a new place. I plan on breaking up the smallest garden area I've ever had. Just enough to grow things like corn, okra, purple hull peas and pintos.


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