I am wondering about whether or not I absolutely need to have an ebb and flow type setup with a timer on my PVC hydro system or not?

I do not yet have a timer, and plan on eventually purchasing an ART-DNe timer, but it's difficult to accumulate equipment for a grow when your already struggling on disability.

I previously tested my setup with veggies for a few months, and had the pump running constantly, and everything took off and grew like crazy, especially my tomatoes, so I'm wondering, why not cannabis in the setup as I currently have it??

I actually have it setup so that there is alot of bubbles in the reservoir, and also, where the water enters the PVC tubes, there are jets that really oxygenate the water, so I'm guessing that's why the roots of the plants did so well.

So, can cannabis grow like this, or is there a reason the roots need to "dry off" a bit to mimic the natural watering cycle in nature?

Thanks!

Sounds like you've got a recirculating DWC system, also know as an Undercurrent.

These are AWESOME for cannabis my friend! They do not have any reason to dry off as long as their is sufficient aeration in the water, which it sounds like there is. I personally have an airstone in each individual bucket running off of one air pump (200L per minute). Not necessary, but the better aeration, the better the growth.

As far as weeks 5, 6 and 7 of flowering go, drop your system's water level to about 1/3-1/2 high. This will replicate a "drought" situation, and cause resin production to skyrocket during peak flowering period.

PH from 5.6-6.2

Goood luck!

Well that is awesome information!

Nice to know I'm finally doing "something" right...lol.

I guess the only difference is that I'm circulating the water through PVC pipes rather than in aerated buckets right??

Below is a pic of my setup thus far, I have yet to hang the black plastic curtain around it and to cover over the unused openings to keep algae from growing.

Does this look like you envisioned it?

Why would people bother messing around with the pump being on timers if it works just as well with a constant flow??

I've got a layer of hydroton in the basket that makes contact with the water, and the rockwool sits on that, as well as having the rockwool surrounded by hydroton, that's how I did my veggies and it worked great, what do you think?

Thanks again for your reply!

That looks like an awesome little system my man! How full are your trays as far as water goes? Are the majority of the plant base and roots submerged in water? Or is it a small current of water in the trays constantly recirculating? Or do you in fact have an aeroponic unit on your hands - where there are sprayer heads misting the roots at all times?

Just trying to get a feel for your system before giving you potentially false information man!

If submerged; Constant flow, always.
If NFT (Nutrient Film Technique, small stream of nutrients on bottom of tray); Constant flow.
If aeroponic; It's preference. But I've seen great results with a 1 min on, 4 min off timer, along with great results from a 15 on 15 off timer. Cannabis likes it's wet/dry cycles if the option is available. In DWC (Submerged Roots), you don't get that drought-like environment unless you manually drop the water level or only top it off to half way. But as far as aero goes, I'm sure there are studies out there showing which results in faster growth, but constant flow or an on/off cycle is going to be just fine.


edit: Post #420

The water comes up and just touches the bottom of the basket, and thus the water wicks up the hydroton, and also into the rockwool.

There are no roots yet, these plants are only 3-4 days old.

Eventually, when there are roots, they will dangle into a constantly flowing circulation of water that enters at the right end of the tube, and exits via an overflow tube on the left side.

Unless I drop the water level as you suggested, the roots will go directly into the nutes and be completely in contact with the nutes at all times.

Do you suggest any kind of gap between the bottom of the baskets and the circulating solution once the roots are long enough to dangle into it, or should I maintain a high enough level (as it is right now) so that the nutes are always making contact with the basket to keep the hydroton and rockwool saturated?

I have a submersible pump in the reservoir below, and that pump pumps water up into a manifold that divides the flow from the pump into 3 outputs, which I've fashioned a jet and inserted into the top of each tube.

The water flows down in a jet on the right side, and then overflows back into the reservoir on the left side.

It wouldn't really work as an "ebb and flow" system because the input of the water into the tubes is fed from the top, not through a hole in the bottom which would allow for the nutes to flow back into the tank when the pump would shut off, so I'm glad this will work as a constantly running pump system.

Originally, I had planned it as a kind of aeroponic hybrid system that I thought up, but the pump was just not sufficient to give any kind of mist to the roots for some reason, so those mini jets misters are just sitting there unused, ignore the thin black tubing that snakes around the pipes, it's not actually doing anything...lol.

Thanks again for your help, this is my 1st grow indoors, and also in hydro, so it's alot to take in, especially when I'm in so much pain i can't even think straight!

ok well you have a setup that kinda works like a aeroflow but no sprayer or spray tubes. there is a name for this kind of system can't runmeber it off the top of my head. but yes you will want to lower the amount of water you have in the tubes. not sure how far as i use a aeroflo. but i would think that you would want the roots to wick up the water to the rest of the plant not the hydroton. thats if i am explaining that right. if not i am sure some one will say something as i only have 5 years under me and others here have alot longer.

Yeah you've got yourself an NFT/DWC Hybrid system in a way. With NFT (Nutrient Film Technique), the nutrient level is quite literally a small FILM - this is describing the size of the stream of nutrients. If you can imagine this;



This is NFT. Your system seems as if the water level is a little higher, submersing your root system - which is JUST FINE!

I personally would keep the system just as you have it. It's an Undercurrent essentially - and I love it.

If at all interested, since I'm guessing you have a couple of inches of water in there, I would think about adding some Air stones (or air stone strips, the elongated ones) to your trays. This would just up the aeration as if it were a DWC system.

Don't get me wrong, it sounds like you have plenty of air, but to steer you in the right direction, that would be my only addition to the unit. Otherwise, you've got a sweet setup my man. Can't wait to see it produce!

To answer your first question, and you've kind of already done it yourself, but yes; Keep this system constantly running and circulating.

Good luck man! I'll help out as much as I can! I love my undercurrent systems!

That's EXACTLY what I have!

The picture matches exactly what I've built, except I do not have my tubes slopes to create an angle for the water to run in one direction, I had a slight elevation on the water feed side, but found that the baskets at that end were not touching the water, and at the exit end, the baskets were submerged almost an inch, so I leveled it off.

I appreciate the tips, and will consider adding the additional airstones when I can afford them.

I have an industrial air pump originally used for a medical nebulizer that pumps a crap load of air, but it draws 3 amps of current, so to have that running all the time would suck too much energy.

I currently have this system running almost solely on solar power, and have to be exacting in how much I load the system down, I still as it is have to switch it over to house power once the day is done and the sun starts to go down, eventually, when I can afford more solar power upgrades, it will be completely off grid.

On the water supply hoses from the pump that feeds the tubes, I have a 45 degree 1/4"fitting at the end of the tube coming from the pump which I melted the end and sealed off, then drilled a smaller hole to create a jet of water that enters the tube, so it really does aerate the water very well.

What I need is more light, and I will be adding that as soon as flowering stage comes, some 2700K CFL's.

I'm still a little confused about the nutrients and what to use for flowering and the veg state, whether I can use the same ones for the who grow, or if I need to use 2 different ones or not.

I bought "Aqua Flakes" from a guy in Vancouver who said it was good from start to finish, what do you think?

The other thing I'm wondering is about how long to veg the plants for before switching to flowering as I have a tiny 5ft x 3ft x 5ft high space to grow them in, so I'm not sure if I need to prune them, or how to if I do need to.

Any suggestions?

Thanks again for your help!!

I woud not veg the plants at all in that system. With good growth rates, you coud run into problems with the plants being too big, especially the roots.

Can you post a pic of how the water is aerated?

I'm wondering if this system would require or benefit from a low water temp. I ran my aero system at 62, saw a marked improvement from 68, but my dwc systems can get over 80, my veg system is at 82 right now. No root damage with that, but the airstones bubble right up into the roots.

I know with commercial NFT systems, the runs are long enough that the solution has to get to ambient temp, but that is just a film, the majority of the roots aren't totally submerged. If they are in your system, you might have a little different temp requirement. I don't really know. It's one of those things that will probably take a little tuning/dialing in to get right.

Here is a pic of the water jets inserted into the tubes.

I now realize that in the few days that I've left the water jet tubes unshielded that algae has accumulated in the line, grrr.
I have to shield it asap.

I was totally amazed that after only 5 days there was a 4 inch root already hanging into the solution!