Advice, Opinions on this Tray Ebb&flo/Dwc System

Whew!! what a relief!!!!!!!!!!!

Did you end up backing your timings off as well? Also, did you lower the water temps? (though 65 seems like it's perfectly fine)

I just did some quick math on my ratios, and I use 6.8 ml/gal and replenish every 2 to 3 days. So I guess that puts me at a replenish ratio of 33-50%? I may be overdoing it though.

Soon, if not already, you'll be pathogen free, and then maybe you could back it off to 7 or 8 ml/gal and then slowly back down untill you find the sweet spot.

I'm not sure where you get your H2O2 from... but I get a pretty good price on 29% from pool supply places. I've used it for over a year with no ill effects.

CoreyPKGrower said:

Well four days in and things are looking up. ! Yellowing has stopped and some of the plants I striped roots off are starting to sprout new roots... Sweet !
I'm at 15ml H2O2 / gal. And its definitely working well. Ph has now stabilized at 5.9. Roots that were slightly brown are clearing up as well.
Bud is really starting to pack on some weight now. 3and a half more week to harvest !
Now I just need to figure out what the replacement ratio of the H2O2 is. B4 I was using 5ml/gal and replenishing at 25% per day. With these high levels I wouldnt think it would be 25% any more...
Anyone have any thoughts on this ??


View attachment 1530124

Looken gooood...

Click to expand...

Yeah man keep us updated. I've been screwing around with the same method on a much smaller scale, suspended pots in flood/drain, and am really interested in your setup. I'm on my first run now and yer roots look better than mine man!

Thought I would update my post... Well I got my O2 test kits yesterday. They work great and simple to use. $12.00 per kit and gives you 30 tests per.
So I did first test just b4 the lights came on. Tested at runoff from the tray. Temp was 65F. Test showed around 5-6 mg(ppm) per liter. Out of possible 9.4 at temp 65F.
Assuming there is more O2 consumption in the roots during the dark cycle... I guess thats not too bad. Dumped and refreshed reservoirs the day b4 and H2O2 was added at 15ml/gal.
With this test kit I may be able to compute H2O2 requirements now..
Here's Pic of test kit and color result in vial can be seen.


Overall the plants seem to be doing ok. Buds are forming nicely and they just finished up week 4 flowering.
However... I'm becoming convinced that root bounding is an issue with this setup. Flooding and draining the tray just doesn't give the agitation required for good nutrient xfer thru the dense root mass. I dont
believe air stones under each plant will work either because of the drain cycle. Roots will always hang down. Im thinking I may need to add a small 6x6" RW slab directly under each plant during placement. This would
prevent heavy root bounding directly under the plant. But than would mean basically going back to RW ! Kinda defeats the purpose of this experiment eh...
I think raising the plant in the tray would help alot with the initial root bounding that begins a week after transplant. Just need to figure out an effective way to get root agitation(movement) to prevent or at least slow root bounding.



Getting close to the lights but the light mover prevents excess heat in the tops. (Tested)



soooo pretty... lol



Might not look like it. But that head is almost a foot tall !!

Stonetech said:

Yeah man keep us updated. I've been screwing around with the same method on a much smaller scale, suspended pots in flood/drain, and am really interested in your setup. I'm on my first run now and yer roots look better than mine man!

Click to expand...

Good luck with it man !! Its been tricky at best for me so far. I'm really only doing it this way because of disposal/ volume issues. If I were growing a smaller number of plants I would stick with clay pellets, Rockwool, etc.
But kudos for you trying !! Uses H2O2 !!!! and if you can list your plant up and out of the holes daily. Do it ! Helps slow root bounding.
I plan on extracting some water from my root balls 10 minutes or so after watering cycle. Test the O2 levels on it. I bet it will scare me.....

Also... I will be getting another batch of clones next week. I'm going to be doing lots of testing on them. I will block the bottom of the mesh pot on some to prevent root growth directly out the bottom. The plants I'm dealing with now I blocked
root growth out the side. A mistake at best !
Others I will allow roots out side and btm. Also I will be testing some ideas on easy recyclable non porous particles under some plants. Heavier material wont float or be easily displaced by root growth. If roots grow in and amongst it that will
prevent heavy root bounding I think. Along with more research and testing other ideas.
The whole plan here is to not use a pain in the ass grow medium and couple flood and drain with DWC.

Oh ya... Wilting during the dark period. I have a post on that problem here... https://www.rollitup.org/marijuana-plant-problems/417914-purple-kush-wilting-during-dark.html
I found out it was because of lack of O2 levels in nutrient ! When I added alot more air stones and big air pump. The problem went away immediately !

Awesome update, thanks for keeping this thread going.

couple questions.... Are your plants showing any signs of nutrient deficiency?

Do you keep the same flood/drain cycle for 24 hours? if not, what are the timings during lights off?

Just an observation... but, H2O2 is only needed to control pathogens, if you use it to up your Disolved Oxygen in the nutrient solution, that could be expensive!

Roots do need oxygen, and that can be accomplished by your timings. I run no airstones in any of my reservoirs (except for my EZ cloners), oxygen to the roots are controlled with flood/drain cycles.

I highly doubt that your plants have any issues with root binding, seems to me they'd be showing ill signs. Do you feel like the plants should be doing better in week 4? because to me they look GREAT! especially with your limited height capacity. Also, if you block off the bottom of the netpots, and have roots only coming out of the sides, you'll find that you wont be able to pull your netpots out of the sign board.

Also... you could grow your plants with no media at all, just neoprene collars and 2 inch net pots. Though you'll likely not be able to use the collars again, as they'll probably stretch out to accomodate the stems, but you're talking very little, and stealthy waste. make an "OK" sign with your hand, and that circle is about the size of the neoprene collar, by about an inch thick. Cost is probably cheaper than rockwool. Just an idea to eliminate all media.

what you're doing with your setup is fascinating to me. I love it!

oh yeah, one more thing.. Though in my opinion I dont think it's necessary, they have mats made out of coco or other materials that you can place in the bottom of the flood tray, the roots will dangle down and then grow into the mats. This would disperse the roots a bit more, but then you'd not be able to pull your netpots out of the signboard. :/ That's only if root bounding was an issue, which i dont see how it could be in this situation.

what about the possibility of netting? a few layers on it spread out over the root gap could do the trick and could be washed off with a water hose or pressure washer pretty easily. IDK just a thought.

Awesome update, thanks for keeping this thread going.

couple questions.... Are your plants showing any signs of nutrient deficiency?

Click to expand...

No. Only the ones I had to trim the roots on or the ones that I cut all the roots away. Other than that... Minor lower leaf yellowing and drop. About average

Do you keep the same flood/drain cycle for 24 hours? if not, what are the timings during lights off?

Click to expand...

Its the same timing day and night. Couldn't change it much anyways cause of the required cycle times.

Just an observation... but, H2O2 is only needed to control pathogens, if you use it to up your Disolved Oxygen in the nutrient solution, that could be expensive!

Click to expand...

LOL.. Ya at 29 bucks a gal. But well worth it if it keeps them healthy. Im backing off on it now and will monitor O2 levels as I go.

Roots do need oxygen, and that can be accomplished by your timings. I run no airstones in any of my reservoirs (except for my EZ cloners), oxygen to the roots are controlled with flood/drain cycles.

Click to expand...

Dont think I can get away with that... I have lots of aeration in the reservoirs now and it has helped alot.

I highly doubt that your plants have any issues with root binding, seems to me they'd be showing ill signs. Do you feel like the plants should be doing better in week 4? because to me they look GREAT! especially with your limited height capacity. Also, if you block off the bottom of the netpots, and have roots only coming out of the sides, you'll find that you wont be able to pull your netpots out of the sign board.

Click to expand...

I should have mentioned... I may splitting the sign board down each row of holes. Then I can disassemble the whole thing as I remove clones for transplant. Same for flower room. Reassemble lid as I transplant. I hope not to have to do this thou... Yes the plants are fine but I want to fine tune it and have white healthy roots. My roots are a little brown and got that way slowly from the beginning. More so as the root mass became larger and dense. I think root growth is minimal now too.

Also... you could grow your plants with no media at all, just neoprene collars and 2 inch net pots. Though you'll likely not be able to use the collars again, as they'll probably stretch out to accomodate the stems, but you're talking very little, and stealthy waste. make an "OK" sign with your hand, and that circle is about the size of the neoprene collar, by about an inch thick. Cost is probably cheaper than rockwool. Just an idea to eliminate all media.

Click to expand...

eek !! been there done that. Too many cases of damp off . They hold too much moisture right around the stem making it week and constantly wet. Works good for clones thou.
I'm using the disks from the signboard holes I cut. Bore a 5/8" hole and slit them to clear the stock. The clones are very delicate and arrive in a small RW plug mostly. I have found transplant into 3.5" cube best with the least failure rate during the first week. I dont mind using just the lil cubes as the wast is minimal and reliability is excellent.

what you're doing with your setup is fascinating to me. I love it!

Click to expand...

Well you come here and fix it if u love it so much !! LOL...lmbo... hehe. sorry. Yes I'm enjoying the challenge at times I guess. I'm usually persistent and that pays off..

oh yeah, one more thing.. Though in my opinion I dont think it's necessary, they have mats made out of coco or other materials that you can place in the bottom of the flood tray, the roots will dangle down and then grow into the mats. This would disperse the roots a bit more, but then you'd not be able to pull your netpots out of the signboard. :/ That's only if root bounding was an issue, which i dont see how it could be in this situation.

Click to expand...

Good Idea but ya. Removal and placement a problem after. I dont think bounding is really serious but based on what I'm seeing. Its definitely affecting plants performance. Pictures look good but dont tell the whole story in this case.

Hey Corey I have the same problem with my roots, they outgrow the space and become matted. Like a sponge they just won't let go of moisture, the only thing I can do is feed less frequently (like every 4 hours). I've only got about 1.5" of space between the bottom of the pot and the flood table so they don't have enough depth, except when they're small. Nice idea with the o2 tester, I should go grab one from the pet store. Right now I'm just experimenting (like you) just on a MUCH smaller level. You got some balls trying something new with so much goin on! Kudos to you!

BTW I am using hydroton in my 3" pots, I'm not trying to do it without any media just as little as possible. I'm also using a tee diffuser to oxygenate the nutrient during the flood instead of using any airstones (I have the equip I'm just trying to find a better way). I'm trying to do without h2o2 as well, just oxygen rich nutrient and proper feeding cycles to keep the rot away. I've been fooling around with some other things like a venturi and ventilating the rootzone. Right now I'm doing more experimenting than I am growing.

Anyways, not tryin to jack your thread just very interested in what your doing. I've been thinking about mixing rdwc/ebb & flow for a while now. Your plants look great BTW.

No worries about the hi-jack Stonetech ! All are welcome here.. WOW ! 4 hours ? Thats interesting. Ive been afraid to go much over 26 minutes. Thats what I'm running now. After some actual scientific research, dry and dull for the most part..lol I have read that extended dry time on root matted, bounded plants can make the O2 deprivation even worse ! Reason being is the film of water remaining on and in the root mass becomes quickly depleted of O2. Unless of course there is substantial air movement within. Which would then dry out the roots !
I had increased dry time by as much as 45min but noticed quickly things were worsening. So backed off to 26min. Im considering going back to 15minutes as there is alot of turbulence in the tray as its filling with nute.. And thats better than the roots laying there just wet.
Ya my space is about the same and I will be increasing it by another 1" or so by raising my lids and extending the support legs.
Lol ! Balls or stupidity ? When I started this I actually didnt think I would have any problems. Wile the plants are doing ok. I know they could be better and roots should be white or tan. Not brown.
And I toyed with the idea of aggressively ventilating the air in the tray too. But thats not easy ! Air would be warm and could never get even air flow. Some would dry out and others still be wet.

Yeah generally the best root growth I've noticed at 15min on/45min off, until they become matted. Although I've been starting clones with 15 on/15 off until the roots are couple inches. Maybe I need to shorten my flood times instead of lengthening the rest period. You said you just flood long enough to fill and then drain right? I've got a digital timer somewhere round here I should give it a go. It should only take about 7-8 mins to fill. Thanks.

Stonetech said:

Yeah generally the best root growth I've noticed at 15min on/45min off, until they become matted. Although I've been starting clones with 15 on/15 off until the roots are couple inches. Maybe I need to shorten my flood times instead of lengthening the rest period. You said you just flood long enough to fill and then drain right? I've got a digital timer somewhere round here I should give it a go. It should only take about 7-8 mins to fill. Thanks.

Click to expand...

Ya I had to make my own timer unit. top tray flood runs first. Takes 4 minutes to fill 2 4x8ft top trays. Then it gravity drains as well as 2 small impeller pumps running back to reservoir. drain takes 6.5 minutes. Then btm trays pump runs takes 3.5 minutes to flood. Then 3 pumps run to drain bottom. 7 minute drain time. Then it starts all over again. But I can add any wait time between cycles. This way the water is always moving in the tray by draining or flooding.

Well I think from what your saying I need a good cycle timer and maybe a stronger pump. Your cycle sounds pretty turbulent for sure. Not really wanting to buy a new pump for an experiment though, I'm just using spare shit right now. Just out of curiosity how big a pump do you think I would need for a 3'x3'?

Another idea I had was to buy a couple submersible powerhead pumps used for aquariums. You could mount them right inside the tray, maybe this would be too turbulent though, not sure how powerful they are. The thing I like most about them is that they have an adjustable venturi built in, oxygenating the shit out of the water.

BTW I have been fooling around with a fan mounted on my lid, I know its wrong but I just had to try it. I mean in theory its almost like throwing a supercharger on an engine right? LOL. I mounted it in the center because I've got my light vertical and already had the fan sitting there anyway so I'll just cover the hole when I'm not using it. All I did besides cut the hole was add a speed controller, which I needed anyway. Started out flooding 15min on/15min off with about 10-20 cfm(just a guess) pulling air through the net pots. I gradually increased to 15min on/30min off and about 80-100 cfm before I noticed the roots thinning out. At least when they did thin out I was able to tell that the airflow was fairly even through all the pots.

Right now I'm just running a normal cycle (15min on/45min off) with the fan on the same timer as the pump, with no ill effects. Need to get one of those o2 test kits from the pet store and see if any of this is adding o2 to the nute, I guess none of my results can be conclusive unless I measure the dissolved oxygen. How did yours work for you? I've never used one before, I only know they exist because you mentioned it.

Sorry if your thread is turning into a bit of a tutorial but I really do appreciate any help or feedback. Cheers.

Ya know... I really like your fan idea. Particularly the sucking air out of the tray vs blowing it in. There would be much more even flow thru the system. I just did an O2 test this morning. Levels at 5-6mg/l. About the same as last test. Its been two days since I added any H2O2 to the system and I had 15ml/gal. So without topping up H202 and adding about 8 to 10 gallons of water to top up. The O2 levels are about the same. Today I'm going to be testing O2 levels in H2O2 treated and untreated samples. I'm sure I will be backing off to 3 to 5ml/gal soon thou. My O2 levels should be at 9.0 or so and there not.

Well I think from what your saying I need a good cycle timer and maybe a stronger pump. Your cycle sounds pretty turbulent for sure. Not really wanting to buy a new pump for an experiment though, I'm just using spare shit right now. Just out of curiosity how big a pump do you think I would need for a 3'x3'?

Click to expand...

Well it depends on your system. Lift height from tank, and pipe diameter. Even smaller Pond pumps rated at 900 GPH do a poor job when lifting 3 feet and or pumping thru a 3/8" line.
I always use bigger pumps and add bypass valve back to tank. Then I can adjust PSI and flow. You want to fill your tray quickly for sure. Maybe add deflectors on tray ports to prevent root tearing closest to the intake.
That said.... A 600 to 900 GPH pump, here they run $35. Home Depot. Should be fine if your not lifting more than a foot and using 1/2" line. Im assuming your draining thru the same line you pump?
I tried circulation pumps in the tray but had no success. Roots slow the flow down to quickly. And I saw no difference in root health near the pumps as opposed to the other end of the tray. Results may vary of course.

The O2 TETRA brand works well. I have not tried using other brands simply because of availability. Tetra is simple. Fill vile 15ml. of your water. add 5 drops of agent 1, then 5 of agent 2. Flip vile once. Wait 30 seconds, then add 5 drops of agent 3. Flip twice and
compare against chart.
No worries about posting ! Glad to share info and experience. And I'm no expert ! So I'm learning from you too !!

I have learned alot on this hydro method so far... But on the next run I will be monitoring things more closely. I'm going to cut out 4 larger holes in each tray and use an insert to match the 4" pot. So then I will have a 8" hole to pull the plant out for easy inspections daily. Also during 3 week veg I will not allow roots to come out sides of pots. But when I transplant I will remove barrier to allow roots to grow out sides and bottom. As well I'm going to test watering cycle times on them. I'm sure there's a optimal rate here, just need to find it !
Some plants are much better than others for sure. Diesel and similar plants have better characteristics for this hydro method. Purple Kush is the weakest plant I have ever had the misfortune to deal with. But alas... That's what the market demands.
Right now I'm busy working on a similar setup. This one is using 8ft long box trays. With drip feed and flood & drain boxes.

Hey Corey, I forgot to ask what your flood level is at. Mine is about .5" up from the bottom of the pot. Do you lower the flood level as the roots expand like you would in DWC? I think maybe this is what I'll try if things get hairy again.

I'm using Dr. Atomic's NL x DJ Short's Blueberry, it's very resilient and perfect for experimenting. I've also got some OG Kush waiting to be sexed, for when I've got my shit together..

So yer already on to another build, man I'm having trouble keeping up!

No mine floods to about 1" up the pot. Cause I have a 3.5" Rock wool cube in the pot I cant let it dry out.
Oh yes... Love the blueberry strain. They are awesome !! You can step on those roots and they will keep on going.. Its been the Kush at the cause of my lack of sleep ! lol
Kush is difficult in water gardens. I was going to experiment with other more resilient strains but since I knew Kush was what I wanted I figured no point testing with others.
LOL ! Ya another build... More a modification of an existing one really. But the principals are similar to this one. Im also finishing up my auto-feed system. It adjusts water level, ph, and 3 separate
nutrients. Micro, grow, bloom. Then my system is hands off other than inspections of course...


Here is the principal of operation...

Shit Corey, your like a mad scientist, LOL. I love it! That auto dosing is WAY beyond me man, but keep it up. Keep us updated on your current grow as well, wouldn't mind seeing a pic or two before you chop. Cheers.

I got a little update of my own actually. Things have really bounced back since I stripped most of the roots off all the plants only leaving the taproots. The roots have regrown and are looking good.

Here's a pic of the Atomic Jam about a week before I stripped the roots and started over, flooding 15min on/ 45min off.



Here's a pic of the quickest to recover. This is just before the flood (same cycle) and as you can see the roots are nice and fluffy, damp but not dripping, just the way I likem.



I'm still running the fan during flooding and I doubled up the trays. The inner tray has a bunch of holes drilled through it kind of like a big net keeping the roots out of the nutrient that remains in the lower tray after flooding, its about an inch higher.

Things seem to be going better than last time but that could quickly change when I start gettin more lateral root growth.