Pea Gravel in Ebb & Flow

[Glass Man]

Maybe I should ask this in a new thread, but this one's rolling pretty good. ;)

I'm interested in Eb & Flow, but I don't want to use Rockwool. I'd rather use plastic pots, either 4" or 1 gallon (actually my 4" pots are sorta "jumbo" ones, and my 1 gallons are the smaller ones I think are called "trade" gallons). I figure I'd fill them with pea gravel. I would construct the table 4x4 from plywood covered with pond liner or 6 mil. Does all that sound okay so far?

What's a good size resevoir for that size table, about 50 gallons? Or is that extremely large?

Is pea gravel okay? (I don't have a hydro store near)

What's a good watering cycle to begin with?

What's a good table depth? Is 5" enough?

About how high do you need to fill the table? And how long is a good fill cycle time?

What else should I consider?

Thanky,
GM

[GrowGreen]

Glass Man

Make sure you wash the Pea Gravel real good. Baking it in the oven would be nice as well.
Construction Grade 1/4" would be your best choice.

Under big lights (600w plus), you’ll need to flood it often. Like every hour. Pea Gravel is not known for its water holding abilities.

:peace:
GG

[Glass Man]

OldSog,
By "floods per cycle" you mean each 24 hours? Or just when the lights are on? Why do you flood less often when young, seems like little roots would dry out quicker?

I'll construct table to work with the larger, 1 gallon, pots then it will also handle the shorter ones too.

As for the "strain, plant numbers, and growing style" I figure those are variables which I could decide on for each crop. The system seems pretty flexible that way, considering it can accomodate a variety of container sizes. One crop I might to try trees and the next I could SOG, that seems like the beauty of an ebb & flow.

Actually, I really like 400s. I know many of you guys think that's not enough light but I like them. Maybe I'll learn better, someday. I've been using a 4x8 Keef Treez grow tunnel with 3 400s for a while now and it jams. I'll use a full size 4x4 hood over the e&f table and mylar on all four walls to maximize refectivity. If it's underpowered I'll reduce it's area a little, to a 3.5x3.5 or a 3x3.

I'll go take some bud shots from the tunnel and post em' in a little while. You'll see why I'm a 400 fan.

Thanks for the tips,
GM

[Lucas]

> Maybe I should ask this in a new thread, but this one's rolling pretty good.

yes, but you are hijacking it with a series of beginner questions on how to build your own ebb and flow table
I think it would be better if you did start a new thread, please

with all due respect, here are a few of the pieces of the puzzle you are working on

> What's a good size resevoir for that size table, about 50 gallons? Or is that extremely large?

when considering gallons, I base the answer on watts
for 400 watts I recommend 20 gallons

> Is pea gravel okay?

no, it does not have pores like clay rox or Lava rox
pores in the medium are beneficial, smooth hard rocks dont have those pores, so will provide less of whatever it is thats so good about pores..

you could try mixing your gravel with peat moss, to increase pores, if you cant get the Lava or rox

> What's a good watering cycle to begin with?

set it and forget it at 15 minutes every 2 hours (disclaimer, do more research, get more expert opinions..)

> What else should I consider?

I think you should read up on ebb flow, and start your own thread with questions you could not find answers to by using a search feature

and I think you should consider that water is heavy, and ebb flow on a 4x4 area will use 50 gallons in a 3" depth

so if youre only going to put a single 400 watts of total light down, you dont need a 4x4, cause you cant fill it more than 3", before using up a ridiculously large amount of water..

you ask good questions though, and raise an important factor, the interaction between irrigation depth and pot size in ebb flow

it deserves a thread of its own, how to manage plants grown in a conventional ebb flow table that is flooding to a 3" depth, and what that means to pot size, and total gallons of medium in the pots...

thanks for keeping it interesting, dont be put off by my coarse attitude, I appreciate your curiosity

Lucas

[c-ray]

ask and ye shall receive...

[Glass Man]

Hey Lucas,
Sorry for hijacking, thanks for being cool and also helpful about it.

I see what you're saying about trying to flood large containers and the water volume required to do it getting out of hand. Probably a better job for drip/spray emmiters. That's why folks use Rockwool I'd assume, because it wicks and doesn't require the depth. Okay that makes sense.

Maybe I'll end up going with an extra porus soilless mix and automate the watering with emmiters, a pump & timer, and a res. That sounds like what I might want. Sort of a hydro/soil hybrid system. I know I'm not inventing anything new...just thinking out loud. :)

Peace,

Oh btw, GG how'd you know I've got really hot big ovens??;) I can definitey destroy some evidence around here!

[Glass Man]

Here's a couple of shots that I just took today. This is what I'm getting using the 3 400 watt HPS in my 4x8 grow tunnel. It's called SWC. I keep the water depth at about 3" and it recirculates 24/7. The table has spray nozzles feeding the nutes at each end from above the waterline. There are no airstones on the table, but I do keep a couple of little ons going in the res (doubt they are necessary). Maybe I could use bigger lights, but I'm pretty thrilled with what I'm getting with these. This was supposed to be a SOG grow, but the plants stretched much more than I'd planned. Rather than reduce the plant numbers I chose to thin out the lower branches, Pistilwhipped style. The trics are all still crystal clear, so I figure to be waiting another week or 2.

Peace,

Hmmm, the attachments won't load. The size should fit jeg 480x722 , 161KB. Wonder what I'm doing wrong? Can someone help? I'll go look for & read some tips....& be back.

[Jake Blues]

oldsog i got question about how you run your flood tables.
my table has a top with 6" net pots the way i was told and have done my water levels is just high enough to get my rockwool wet,and flood for about 15 mins..now it`s worked for me so far.but will your method help me any.

[GrowGreen]

Oh btw, GG how'd you know I've got really hot big ovens??

I pay attention to what people say..

Speaking of, pick a guru that know what they are taking about. Someone like Dr Howard Resh..
Pea Gravel will work just fine, porous or not. It was used in Ebb/Flow for many, many years before the invention of Hydroton. Still used today in many e/f gardens. You must clean the hell out of it before the first use, flood often as well..

:peace:
GG

[Glass Man]

GG,
I agree that pea gravel would be fine in smaller containers and many flood cycles. But I also understand the point that Lucas made about the deeper pots requiring too deep a flood depth to be practical.

Btw, If you like fire, you should see some of my ovens and furnace. The ovens that I use for cooling the glass can get up to 1800+f deg. They will turn aluminum into a puddle and can deform 3/4 inch Stainless steel plate. And that's just an oven, the furnace and glory holes really get screaming hot. The furnace idles at 2100f and the Glory can get up to 2500f, which is a bright yellow.
Being around all that fire you can see how growing, and especially hydro, balances out that fire energy in my life. Gota' have Yin & Yang, right?

[Lucas]

> Maybe I could use bigger lights, but I'm pretty thrilled with what I'm getting with these.

cool! you are using 1200 watts to get a yield you are happy with. congratulations..

what IS your yield? if you get 29 ounces off the table, you are getting 1.5 pounds per 1k, which is better than many.

However, to match a 2 pound per 1k yield, your 1200 watts need to produce 38 ounces.

and thanks to GG for illuminating my ignorance about the use of pea gravel. Apparently the medium has absolutely nothing to do with the success of ebb flow in delivering nutrients as well as oxygen to the roots..

thanks
Lucas

[Glass Man]

Hello Lucas,
I've been trying to post shots of the buds, but having upload problems. I'm on my third grow using the tunnel and it keeps getting better. I've be harvesting in another week or two and will post the results. Last crop was plagued by spider mites relatively early on and I should have started it over rather than try to recover...live & learn

Also, for maximizing the yield I really need to monocrop, rather than trying to grow a variety, but I can't seem to stop myself when it's time to take cuttings. I guess I really need to dare myself or something. :) Into going for maximum yield and really concentrating on it. As everyone knows, it's really easy to screw up something along the way. As I said earlier, this crop stretched too far. Fortunately they stopped at the same point that I reached my max ceiling height. Two of my plants are growing into the hood/reflector, but they're okay.

As far as yield goes, I assume the weight is taken after the crop is fully dried & manicured? But before going into the curing jars is okay, because weight shouldn't change after that. Right?

And then of course, weigh you heaviest plant and multiply by your plant number to determine what is possible to achieve as a goal.

I'm sure I'm quite a ways from 38 oz (2.38 lbs). But I'm heading in the right direction!! ;)

[Lucas]

congrats on your solid progress GM

as far as a yield tweak, I dont know how many plants you currently use per the 1200 watts, but the shortest path I know to more yield is to increase plant count.

I dont agree that weighing the best plant is realistic, there will always be some plants that are bigger than others. I think of yield on a per canopy basis, in your case a 4x8 canopy, regardless of plant numbers.

And yes, I track yield as dry weight. there is also a mathematical presumption that my guru pH uses, which is the projected dry yield is equal to 25% of manicured wet weight. I dont agree with that though, because my experience shows my dry down is closer to 19% of wet weight.. I like very dry bud.

point being, people who live in humid climates get more yield, because their dry down percentage is closer to 25% than 19%..

you might do a test.. weigh the wet manicured yield, then the dry yield, and see what percentage dry down you are going to..

hth
Lucas

[Carpet Muncher]

i agree with pH's % for storing.. to maintain flavor/smell w/out worrying about mold.. but i break it out in smaller portions to let it mumify.. for smoking simplicity.

other than that, what's with those mysterious pores?

ps.. irregardless of area humidity, ime, the drying process is completely controllable.. iow, if anyone has ideal specific specs, please don't be shy about sharing them.

[Glass Man]

I hear & agree with what you are saying. I have weighed fresh harvested buds and re-weighed them after dry to get the percentage in the past, but I doubt I can find those notes (it was probably just something I jotted down on scrap paper, and never made it into my notebook). The % numbers you stated seem to be about what I recall. The "weighing the heaviest plant" idea was the ultimate, but probably unattainable goal. Just something to shoot for. We all hear reports on the boards of huge yields, but many of them are only "fish tales".
Let me see if I can post a photo today. C-ray said it's fixed.

Peace,

[Glass Man]

Sorry about the image quality. I need to learn to adjust the white balance for the hps lights. Also it's petty difficult to shoot one plant in a SOG grow, especially when they've stretched to 36" tall !! I wish the entire crop was as phat as this plant.

Peace,

[Glass Man]

C-ray,
Did I do something wrong? The images didn't post to the thread, but if I click on the paper-clip icon thumbnails appear. Arrg...

[Lucas]

> what's with those mysterious pores?

pores hold more moisture, so a plant potted in lava or grorox will exhibit fluffier roots than one potted in gravel, and, the gravel will need to be watered more often because the medium retains less moisture.

the roots in rox are developed in the steam and humidity between the medium, whereas the roots in gravel will be more smooth and stringy, like roots that live under water.

Im afraid to use the term air roots and water roots, cause that is not how I think of it. I think roots simply produce as many hairs as they need to capture ambient moisture. If the moisture is in the form of water instead of steam, the roots will need less sidehairs.

I also dont think of leaves as sun leaves and shade leaves, but they also have a similar adaptation as roots. Plants grown in low light produce more leaves than plants grown in high light. In this example the extra leaves are there for the same reason the fuzzy roots appear in humid airgaps, to capture more of what the plant wants, light in the case of leaves.

just my opinion, Im sure somebody will come along and show me there is a technical distinction between air roots and water roots, but, I believe any root will adapt to the moisture level it is presented with, and will fluff or not depending how wet it is.

that is why it is possible to clone in wet medium, even though you only get stringy roots, not fluffy ones like you get if you let the cloning medium become almost dry..

looking forward to hearing more from GM about plant count and yield per table..

Lucas

[Agent-Smith]

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