Basic math - what am I doing wrong?

[Batboy]

Trying to make my own soil based on the 'Organics for beginners' formula. The problem is that I can't seem to properly convert volumes to suit my needs.

For instance: 1 cubic foot is equal to 7.48 liquid gallons or 6.43 dry gallons according to all the online sources I've seen. Because these are all dry ingredients that I'm mixing (soil, perlite, EWC, etc.), should I just use the dry conversion? All the posts I've seen on this site say 7.5gal/1 cu ft.

Now consider the bag of Fox Farms Light Warrior that I have and will be using for seedlings. It says "1 cubic foot (26 dry quarts)". While this supports the 6.5 dry gallons to a cubic foot conversion, it flies in the face of every calculator I've used which says that 1 cubic foot equals 29.92 quarts.

In short, I need to make a basic mix with a ratio of 6-2-2 (soil, perlite, EWC) and lime at 2 Tbl/gal. I've got roughly 2.2 cubic feet of pro mix, but I can't figure out how much perlite, EWC or lime to use because I don't know the right conversion! I swear I'm not this dumb in real life.




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[CrossEyedMary]

1 cubic foot is equal to 6.42851 U.S. dry gallons. or 25.714 U.S. dry quarts.

The 7.5 gallons to 1 cubic foot is for liquid.

Do you have an iphone? If you do there is a great app called multiconvert. Is the lime liquid or dry? Hope this helps.

 

[cocktail frank]

just mix your "parts" in gallons.
worked great for me.
i'd mix 10 gallons of mix at a time (easier to mix it 10 at a time in the garbage can i used)
6 gal promix
2 gal ewc
2 gal perlite
20 tblspn of d.lime

i would get about 30-40 gallons of mix out of a bale of promix (if i remember correctly, been awhile)

 

[Batboy]

Thanks for the replies. I think that the responses underscore the potential for problems and 'bad math' on this topic. Depending on the conversion calculator you use, the conversions are different! I just looked at 2 calculators online that said that 1 cubic foot equals 29 DRY quarts. Others say 26. . . .

I wish that I could just measure it out in gallons, however I've already got a tub filled with the pro mix just waiting to be mixed up.

 

[Hawk]

Why is there a different conversion for liquid and "dry". Doesn't volume = volume regardless of liquid vs. solid?

 

[cocktail frank]

why cant you take a 5 gallon bucket and scoop out of your tub?
pour it into another tub/can as you measure.
then you will know how many gallons of base promix you have.
use a little stoner ingenuity mang.

 

[IWanaGetHiSoHi]

You really can't estimate the volume of 1/3 of your tub for each amendment ? I don't know if I can help you ... my head hurts ... here's a quick tip ... break it down all the way ... you're talking about a 3-1-1 ratio. For every 3 (6) handfuls of promix you want to mix in 1 (2) handful of white loamy stuff and 1 (2) handful of brown worm shit. This is not rocket science and there is No Need to make it harder on yourself.

 

[Batboy]

why cant you take a 5 gallon bucket and scoop out of your tub?
pour it into another tub/can as you measure.
then you will know how many gallons of base promix you have.
use a little stoner ingenuity mang.

I was trying to avoid this seemingly unnecessary step, but it looks like that is exactly what I'll need to do. Of course now I need to buy another tub. . . .

You really can't estimate the volume of 1/3 of your tub for each amendment ? I don't know if I can help you ... my head hurts ... here's a quick tip ... break it down all the way ... you're talking about a 3-1-1 ratio. For every 3 (6) handfuls of promix you want to mix in 1 (2) handful of white loamy stuff and 1 (2) handful of brown worm shit. This is not rocket science and there is No Need to make it harder on yourself.

While I agree that the concept is simple, your method makes the most amount of work. If only the volumes were consistant, this would be easy, but not when you've got liquid gallons, dry gallons, UK gallons. . . . unless you know exactly what "language" a recipe is written in, you've got no choice but to dumb it down to "3 of these, 1 of these, 1 of these, 3 of these. . . ."

 

[IWanaGetHiSoHi]

Are you really making this big of an Issue over blending some Perlite and EWC into some ProMix? So exactly what are you asking us to do for you? This is what I'm getting from your Original Post and responses - You don't want to work, you can't estimate space, and you want to make this harder on yourself than necessary. Not everyone everywhere measures things the same way so they make Conversion Charts to help those that don't quite grasp the simplicity of it all (note my handful reference). I'm not seeing the world changing any faster to suit your immediate needs (I assume your immediate needs are to get that tub of ProMix amended and in pots/beds to grow weed in) So Get Over It and get to mixing.

 

[caljim]

This is how I do it.

I came up with these numbers for the amendemnts to the 2.2 cu ft compressed bail of Peat.
28 -- 3 qt measures of peat (4 -- 5 gal buckets)
16.5 -- 3 qt measures of perlite (2 1/3 -- 5 gal buckets)
11 -- 3 qt measures of EWC (1 5/8 -- 5 gal buckets)
5.5 -- cups of dolomite lime

Which gives us 55.5 --3 qt measures of mix, the reciepe states that if 3 qt measures are used, 1 cup of dolomite lime is added for each ten parts (or 1 cu ft); 5 parts peat, 3 parts perlite, 2 parts EWC = 10 parts. So 5.5 cups lime.

The blood and kelp meal, and the greensand are called for at 1/2 cup per cu ft. Bone meal calls for 1 cup per cu ft.

This gives us:

Blood meal---2.75 cups
kelp meal ---2.75 cups
greensand ---2.75 cups
Bone meal ---5.5 cups

So easy even a stoner can do it.

 

[Batboy]

Are you really making this big of an Issue over blending some Perlite and EWC into some ProMix? So exactly what are you asking us to do for you? This is what I'm getting from your Original Post and responses - You don't want to work, you can't estimate space, and you want to make this harder on yourself than necessary. Not everyone everywhere measures things the same way so they make Conversion Charts to help those that don't quite grasp the simplicity of it all (note my handful reference). I'm not seeing the world changing any faster to suit your immediate needs (I assume your immediate needs are to get that tub of ProMix amended and in pots/beds to grow weed in) So Get Over It and get to mixing.

I don't know why I'm even bothering responding, as I found your post unnecessarily rude and condescending, but I'll give it a shot anyway. . . .

It is clear that you missed the point of my question, which in essence is very simple -- if I have 2 cubic feet of uncompressed soil, and a recipe that says 1 cup of EWC per gallon of soil, how much EWC is that? I ask not because I am too lazy or stupid to do a simple conversion, but instead because the answer changes depending on what conversion calculator I use. Clearly all I need to do is figure out how many gallons in 2.2 cu.ft. of soil, but that's not easy when the answer can be 13.7, 14.14 or 16.46, depending on which conversion you believe. Of course this answer will determine if I use 4.5, 4.7 or 5.5 gallons of EWC. Seeing as how I've never used this recipe before, I'm trying to stay true to the recipe without adding in my own guesswork.

If you are telling me that you can eyeball a tub of soil and tell me if it's got 13, 14, 15, or 16 gallons in it, then I bow to you oh god of soil volumes. Otherwise, the only real solution is, as suggested by Cocktail, bail out the soil into another tub, measuring as you go.

 

[gogoplata420]

the answer is 42

 

[Batboy]

Thanks for the post Caljim. While I agree with the methodology for your mix using your 5-3-2 ratio, my missing link was (and still is) the way to determine how many gallons are in a 2.2 cu.ft. tub of uncompressed pro-mix, without having to bail it all out while measuring. . . Like Hawk, I thought that volume was a constant and I'm not sure why dry gallons would differ from liquid from UK.

 

[cocktail frank]

why do u need to buy a new tub?
if u had multiple 5 gallon buckets, you could just fill em induvidually for the time being.
if guessing you have containers already if you plan on growing w/ this mix.
or just dump it on a tarp placed on the floor (for easy cleanup)
your options are only limited by your intelligence.
but please stop making a mountain out of a molehill.
this is the easiest part of growing, soil mixing.
only gets rougher from here.

you have been given great advice by every1 here and i will agree with what was said.
i see lazy written all over this thread myself.
it's time to sink or swim.

 

[IWanaGetHiSoHi]

Here is some Truth. There are many charts in publication and on the Internet that give you these conversions. You are making this harder on yourself than necessary. You are making helping you hard on us. If you don't have some seedlings in a 15-5-5, 6-2-2 , 3-1-1 , 9-3-3 , 12-4-4 ProMix to Perlite and EWC ratio by now I don't want to talk to you anymore. Notice how I said And ... I did this because the volumetric value of the Perlite and EWC is the same. If you did it by weight the ratio would not match that of the volume because EWC are heavier (of a higher density) than the perlite. I used the "handful" concept on measure with you because Your handful will be the same in Every Region on this planet. You are the standard of measurements in Your World. Do you Get it Now?

 

[IWanaGetHiSoHi]

Wait ... This is just a really weird way to get us to help you with your Math Homework ... right?