Gravel Floor?

[Sluicebox]

Hello all, A friend asked for my help. Building out a room inside a shop. Gravel floors. Room 11x25x10'+ ceilings. We looked into a slab. Could rent a 1 yd mixer already filled at yard. Then pour a yard at a time? That would be 7'x11'x4 inches. I figured if he went that way could put expansion joints every 7'.

He would love though to just rock it the first run with either the gravel base on it's own. Or he has a large roll of non woven smart pot material on the way. Could roll out 25' of that over the gravel and then black and white poly on top.

Really don't have the scratch for the slab, the poly is already on site, and non woven geo textile 6oz on the way. Is that doable at all?

Media is organic soil 20 gal fabric pots, hand sewn as per thread in here somewhere. Feed is organic teas. 10-12k hps DE lighting. 4-6 tons of AC. Room sealed lights on, 10" can fan can 75 vented to interior of shop during lights out, should be 500+ cfm. There is a second can fan/and filter set up that was just going to run as a scrubber in room. Those inline fans are actually the Gale force 10" inline fan 830 cfm.

So it is a room inside a shop.

Edit.. I listed the fan only as a reference, wasn't bragging about it. Not all fans are the same. It is actually the cheapest one we could find on the site.

Any advice on the gravel flooring or venting during lights out would be appreciated.

 

[Ichabod Crane]

Dont worry about getting every last bit of light reflecting back to the plants. My first run was with 6 mil black plastic walls. Instead worry about keeping the temp right and the light out. The gravel floor wont hurt your plants. It may be a pain to walk on but that dont matter to your plants.

Worry about environment first then light loss. To many people chase that 1, 2, or 3% crap and never start growing. Just run some good bud with what you have then upgrade your room. Most of the good rooms you see here were built over time after running less than perfect rooms.

 

[Sluicebox]

Was really worried about the moisture of the gravel floor causing wpm later. Currently it is dry as a bone in there save for around the perimeter. I think a short run of gutters and a couple of down spouts would solve that.

Then I realized that a slab is going to add moisture (fresh slab) and may be more problematic.

You are one of the Bad Asses in here IC, I'm honored to receive your advice. Not brown nosing but I've seen your work in here. Respect.

 

[Ichabod Crane]

Now that I think about it a good idea might be to spray that floor down with a 10 or 15 percent bleach solution before you start. Just to kill any molds that may be there.

 

[Sluicebox]

The bleach is a good idea. Any thoughts on pulling the lights out air out of the room with that 10"? Would that be too small?

I have two smaller 4 light flower rooms one sealed AC, the other active exhaust running constant while lights on. The room with the active fans looks healthier than the sealed ac.
I want to put ac in the active fan room as well so I can run all 4 lights in there vs only 3. However I feel that an air exchange during lights out would be better than none at all.

Just put that in there to show that I have seen problems with totally sealed rooms. However there isn't a scrubber in there.

Same applies to the room in the shop. Lots of ac, will be somewhat sealed with only a 10" pulling stale, humid air out lights out period.

Would a lung room be the best solution? There is room for one. Could make it 11x8x? vaulted shop ceilings.

 

[Pangea]

I have a gravel/sand base floor covered with geotex, I opted for this over a traditional floor as I have extremely good results by letting the plants grow into the gravel base, insanely good results. If possible, I would never grow inside without letting plants tap into the ground. The cost savings is just the cherry.

Roots will grow through 6oz material, but is still restricted slighly imo, so cut larger holes in the floor cover and smart pot.

 

[Sluicebox]

Thanks for chiming in Pangea. So you just roll out the geo tex and then cut a hole in it where pot will sit? Allowing roots to grow through bottom of smart pot into sand/gravel? If this is correct that is a huge cost savings. Found that geo tex in full rolls 500yds I think for $395.

https://www.icmag.com/ic/showthread.php?t=262977 make your own smart pots thread.

 

[Sluicebox]

I've been thinking about it and I bet they do better on the gravel as they get the rock dust or minerals to suck on.

Hauling in 4 yards of small crushed gravel today 1/2 minus. Then topping that with 2 yards of river sand. Should be lots of black sand in that, those are heavy iron sands.

 

[Pangea]

Yeah, thats what I did, hole in the floor cover and hole in the pots. I also use home sewn geotex pots, gone through a couple rolls over the years, pain in the butt to transplant if your pots are tapered wider at the bottom than the top as you have to un roll them, sometimes its easier to just slice em open if the taper is bad.

I plan on converting my rooms to drying area one day so will just put a reg framed wood floor down when the time comes.

Good luck!

 

[Sluicebox]

Fantastic tip on the tapered bottom, I will work to avoid that now for sure. Just picked up my first roll today. 12.5x360 for 385.00. That's 500 yards! I'm thinking of throwing some various rock dusts down too, just for grins. Guess I won't be lifting the pot to check water lol. Thanks again, solid advice.

 

[HughGhasso]

We have 2 6x8 beds out of 2x12 on a gravel floor, just road base, nothing special. 20 plants/bed under 3k just pulled 4.5 from 1 bed. I think the drainage and airflow from a criss cross of ventilated 1 1/4 pipe on the gravel under the soil was the ticket. Bed 2 is still in process on its first run.

 

[Sluicebox]

Can you give some more details on your criss cross pipe layout and purpose? Thanks.

 

[HughGhasso]

Theres 1/8" holes drilled side to side every 6" or so. The idea was to provide more air to the root zone.

 

[Sluicebox]

That's awesome! Is that Organics? You also said "under 3K" is that 3k HID per bed? I like the ingenuity, remarkable.

 

[HughGhasso]

3k per bed on a 3.5 lightrail.
Its high zoot bulk organic soil from the hydro shop (155$yd3)and the full line of ff nutes. Not my call but it seems to be working.

 

[Sluicebox]

155 per yard is cheap!

Just curious if you had ran those boxes previously with out the pvc? Did you have root problems?

 

[HughGhasso]

That was the first run on this bed. The second bed is considerably less productive however the plan had changed slightly and will be corrected the next run. Bed 2 has same amount but smaller plants and no air grid under the soil.
Next run will have trees and a grid.

 

[HughGhasso]

Roots are just a huge matrix of awesomeness. I was very very happy with the roots.

 

[Sluicebox]

Very good info, thank you. Sounds like more air delivered to microbes allowed for better uptake of nutrients. Add to that warmer soil I'd imagine. Great side by side experiment. Pioneer for sure.

Still studying that pic. So is warmer air leaving from the riser causing colder air from root system to take it's place? Then warm air from room makes it way into soil? Warm aerated soil, more water, faster growth. A form of hydro but for the soil.

Let me know how the trees work out.

 

[HughGhasso]

The general thought was that the fans would constantly push fresh air through the tubes.
We plan on a few runs in the bed before completely replacing the soli and checking the tubes.