Hey all. Just want to make sure this is simple math and there’s no variables dealing with soil
My 30 gallon smart pots are 2 ft wide and 17” deep. Simple cubic foot calculation puts that at 4.45 cubic feet. Is that simple how much soil per pot I need, or do you have experience with those numbers being off when calculating die soil due to compaction etc.
I just went thru 9x 1.5cu’ bags of ocean forest last night. It filled up 14x 4.7 gallon pots, and 15x 3.5 gallon pots.
This is my soil usage per run. Plus 3x 1.5cu’ bags for clones
I’ve been using the ocean forest for all my cloning and up potting and now I’m switching to bulk soil for the big pots. But that should help my understanding
I use OF so I dont have to do any feeding (nutrients) for about 4 weeks. It’s cheaper this way.
I know, I used it because of your advice. And I’ve made it to two months of vegging with almost no nutrients and plants are fucking huge now. Mind you I uppotted a time or two so they usually have access to fresh soil, but yes the ocean forest worked very well for me
OF comes with hyposasis miles. Small opaque/ white bugs. They are good bugs that eat fungus gnat larvae. They move fast (visually) vs slow like a spider mite. But look nearly identical vs SM have mostly a black or red spot on the top.
If you are able to get a tap and pour density of the soil, that is usually the best way to determine a weight per volume for flow-able solids (sands, granules, powders, etc…).
As you mentioned, pouring the soil into the pot vs compacting it into the pot would give you different volumes. Your tap and pour density are the two best ways to look at a flow-able solid weight:volume ratios. These numbers might help you determine how much soil you would need to purchase to ensure you have enough per pot when it gets compacted.
Some brands of media compact more than others. Typical greenhouse pro mix usually contains peat, which differs greatly in volume when wet vs dry.
Happy frog is pretty good stuff, cheaper than OF, not as hot. I have vegged a lot of plants in it. I doubt it has enough nutes on its own to flower without additional fertilizer. The worm casings do the trick.
I only used the ocean forest for early vegging. I’m going to be buying some bulk soil locally for the 30 gallon pots, they are already moderately amended and I’ll be running earth juice sea blast soluble as my nutrients line
I usually count a cu ft of soil as 6.5 gallons that should simplify your math
I’ve been pretty happy with Happy Frog, but I just picked up a couple bags of roots organics. I hear it runs hot, so any suggestions on what to cut it with? Perlite? Corn husks? Both?
Pick a brand of soil that you like. Weigh the bag. Weigh the pot empty. Fill the pot the way you like to fill it. Weigh the full pot without plant. Do math.
Lots of the hort industry uses trade gallon = .75gal to designate pot size. This results in a lot of confusion.
Measuring the pot to determine the actual volume is the best.
If you are buying uncompressed soil by volume the density shouldn’t change much between when you buy it and when you fill pots.
I normally buy %10 over my target volume for spills and additional topping off after watering the plants in. I usually have a small amount left over.
I’ve obviously seen all the calculators and such, just was looking for any experienced tips. All numbers From calculators, to manufactures suggested volume are about the same, so I think I’m good to go 
seems like 4.05-4.65cf per 30 gal bag seems to be the sweet spot. Thanks!
