Looking for some help to increase yield

So I recently converted my room from soil to a custom built undercurrent system. Quality/health of my plants is definitely Much better, but sadly have seen a fairly substantial reduction in yield, will give specs of both setups and grow room to provide as much info as possible...


grow room specs


room size is 6' x 9'10"
-lighting is 3x1000w hps (hortilux bulbs) in air cooled hoods

-air exchange is 10" vortex fan for exhaust running through air cooled fixtures, and intake is 8" canfan max with a custom built air intake filter (uses filters from a central air system, 20x25... 3x particulate filters with a hepa filter at end, sealed air tight to prevent bypass)

-14k btu mini split a/c system

-90p dehumidifier

generally speaking the enviornment of the room is Very dialed in, maintains a solid 78F +/- 2F, humidity locked in at 45% in flower and 60% in veg


previous growing medium was 21x 10g pots with ~7g of soil (used 10g pots to increase the diameter of root base) with this configuration i was regularly hitting 4-5lbs dried/cured n tightly trimmed flower.


the new undercurrent system that ive switched to, consists of 8x 13g buckets & 13g res/control center bucket, using 3" piping between the buckets & reservoir, a 1/2hp chiller, 110LPM air pump, 3x airstones per growth site, and 2 magdrive pumps for circulation (500g/h and a 250g/h) the 500 is setup for direct circulation feeding into res, and the 250 feeds into the chiller n then back into res. water temp is very consistant at 66F


nutrients for hydro setup consisted of
gh floranova bloom
H&G roots excel
H&G multi zen
GH kool bloom liquid
Grotek Bud Fuel pro
GH kool bloom powder
GH floranectar


was able to hit as high as 2300ppm before any sign of nutrient burn and adjusted accordingly throughout the cycle


final yield with the hydro sys in same room was a sad 2.5lbs

i will full out admit with switching to a new growing style i was not experienced enough to lollipop the plants properly and ended up with a canopy around 30" in depth, which is Terrible... even then tho... does not account for such a massive drop in yield


Im not about to go back to soil as i much prefer doing hydro at this point and aside from a low yield, quality is Much better. so basically, someone, anyone who is able to help me get back on track, plz comment! ive invested far to much at this point to turn back now, the potential is there, the equip is there, seems im just, overlooking something that im unaware of

You should only use base nutrients in the uc. 2300 ppm is over 4 ec, there is no need to ever go over a 2 ec. I only go up close to 2 during the stretch, after that 1.2 to 1.5 will give max yield. You need to pump all the water out and then sweep the remaining water out of the control bucket every 2 or 3 weeks. Then refill and put in fresh nutes. Don't use flora nova or anything organic in the uc.
Basically stop using all of those nutrients, get some maxibloom and use at 1000 ppm or below on a .5 scale. It seems you had another thread where you said you had gnats, that means you had root rot. Get some sm90. Put an ounce or 2 in after your nutes are mixed. Keep the water at 68. The main thing is to switch to maxibloom and dont go over a 2 ec and only use that and some sm90. Those other products will only hurt you. Once you have a couple good grows you can switch to Jacks nutrients.

Chemdawggy Dawg said:

You should only use base nutrients in the uc. 2300 ppm is over 4 ec, there is no need to ever go over a 2 ec. I only go up close to 2 during the stretch, after that 1.2 to 1.5 will give max yield. You need to pump all the water out and then sweep the remaining water out of the control bucket every 2 or 3 weeks. Then refill and put in fresh nutes. Don't use flora nova or anything organic in the uc.
Basically stop using all of those nutrients, get some maxibloom and use at 1000 ppm or below on a .5 scale. It seems you had another thread where you said you had gnats, that means you had root rot. Get some sm90. Put an ounce or 2 in after your nutes are mixed. Keep the water at 68. The main thing is to switch to maxibloom and dont go over a 2 ec and only use that and some sm90. Those other products will only hurt you. Once you have a couple good grows you can switch to Jacks nutrients.

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the fungas gnat was a suspicion and not confirmed, upon inspection with scope deff were not gnats... as for the floranova couldnt agree more... after completion i personally felt that it produced a film over the root mass preventing proper nute uptake (wont be using again, going back to 3part base) i am in no need of using something as aggresive as sm90... my room is hermetically sealed and runs a negative pressure vs atmosphere, its so tight it actually pops ears when opening door when inside. as for nutrient strength i had a strong suspicion that being able to hit that lvl of ppm/ec was an indicative sign that uptake was affected, can confirm after harvesting that there was no root rot present, despite what some may think! bugs were noseeums or as some call them "swamp flies" harmless n unable to reproduce in said enviro... simply snuck in while going in and out of room. in terms of temp/nutrients... a lil surprised you suggest a higher water temp than whats being run.... any particular reason why??(simply trying to learn and understand the difference n how it affects roots/plants, from all ive read, best temp for dissolved o2 is 65-67) in terms of base nutrients why maxibloom vs 3part ? from all i know 3 part offers a better ability to adapt to plants needs vs a set ratio on a powdered base... as prev mentioned, not trying to argue, or disagree etc... looking to understand why one has better potential for uptake vs the other... n by all means not looking to have hand held n taken through step by step like a retard lol... just looking for better info on what to read/research as well as exp opinions on best route to venture down

Maxibloom is just the easiest and cheapest. If you do the things I just said you will get at least 5 or 6 on the next grow. I've ran those systems since 2011 so there's that. I like 68 because I've had my best grows there. I swear by the sm90 in the water it helps with nutrient uptake.

Use defoliation technique... yields can be drasticaly enlarged..

You may not need that much ppm. Chillers and pumps, like a/c and lights, can use less power according to design and use. You could run an intake and exhaust fan with the lights on at night, instead of using a/c. And the circulation pumps only need to run a few minutes per hour max imo. So much added heat running pumps and chillers is just drawing a lot of power. That all affects yield. Then either veg longer under smaller lights to get a better filled canopy or increase the plant number drastically until crowding or circulation/mold becomes a problem. I'll try to set a light on a plant, or in the center of some plants, and have the leaves absorb all of the light from the bulb.

the biggest thing i would suggest when people try out hydro is keeping it super simple. i am not talking down to you, you sound as though you've experienced success with soil in the past.

2300ppm is far more than you should ever need, as mentioned by someone else in the thread. i don't go over 750-800ppm in my system. i suggest finding a simple nutrient regiment that has been proven to work in a system like yours. find some threads and copy or adapt what they're doing. after a grow you can start to adjust as you see fit.

i would also suggest looking into VPD. you seem to have the tools to get your environment within the range that you set, so keeping the VPD in a good range will greatly benefit your plants. about 5-6 weeks into flower, ignore VPD and drop the humidity down to avoid rot.

i am no master grower, and i am always learning new things each grow but the suggestions above have helped me get to where i am now in terms of my hydro setup.

simple nutrient programs i can suggest:
jacks hydro - start with the jacks 3:2:1 recipe, it can be found by googling. incredibly cheap and simple.
megacrop - a friend is using this simple 1 part with great success. incredibly cheap and simple. it's literally a one-part powder. smells god awful though!
veg+bloom - more expensive than the powders above, but still quite inexpensive compared to a lot of others. working well for me so far. see the thread on ic for lots of info. dansbuds specifically has been a lot of help for me personally with veg+bloom, so look for his posts.

do you have any pictures of the plants from last run? was yield just poor but quality was fine, or did the plants look a bit rough as well?

Others have mentioned this too, your ppm is too high. you should cut your ppm(nutrient level) in half, at least.

There could be other things that are also affecting your plants too, but the high ppm level is the one that stands out.

You're also running less plants from what you've stated. you where growing 21 plants, and now you are only growing 8 plants. that is almost 1/3 the amount you where growing out before. That could add into your lower yield.

I use a PPK, I heard it spoken of as if they have quite a lot in common with an undercurrent system..
The current thread " Something Wicked..." https://www.icmag.com/ic/showthread.php?t=336515
The thread has been very useful as an ongoing reference.

Poor canopy management is a major cause of poor yield

Like others have already correctly said, your nute concentration is way too high. Active hydroponics already requires less nutrient than soil to begin with, but undercurrent systems are specifically pretty efficient and require less.

Also, throwing another vote out there for simplifying your regimen. Use Maxibloom for the whole grow. You can still use some humic acids if you want, some PK boosters, but in my experience they are unnecessary. Whatever you use, try to keep the EC around 1.0 to *maybe* 2.0 for serious feeders. For the genetics I grow, which tend to feature a lot of landrace genetics, I generally never go much above 1.0.

Chemdawggy Dawg said:

Maxibloom is just the easiest and cheapest. If you do the things I just said you will get at least 5 or 6 on the next grow. I've ran those systems since 2011 so there's that. I like 68 because I've had my best grows there. I swear by the sm90 in the water it helps with nutrient uptake.

Click to expand...

no not doubting your or anything, im here to learn

went n picked up maxigro/bloom today and will be giving it a try..

just got the room replanted today, sitting at 240ppm with maxigro currently

Dog Star said:

Use defoliation technique... yields can be drasticaly enlarged..

Click to expand...

well aware of lollipopping, defoliation and training techniques, been doing this for 15 yrs, just simply new to hydro and this canopy style, first round was never going to be perfect as i needed to see/learn how the plants grew in to be knowledgeable on how to train/lollipop to get best growth patterns. thnx tho.

Goats said:

the biggest thing i would suggest when people try out hydro is keeping it super simple. i am not talking down to you, you sound as though you've experienced success with soil in the past.

2300ppm is far more than you should ever need, as mentioned by someone else in the thread. i don't go over 750-800ppm in my system. i suggest finding a simple nutrient regiment that has been proven to work in a system like yours. find some threads and copy or adapt what they're doing. after a grow you can start to adjust as you see fit.

i would also suggest looking into VPD. you seem to have the tools to get your environment within the range that you set, so keeping the VPD in a good range will greatly benefit your plants. about 5-6 weeks into flower, ignore VPD and drop the humidity down to avoid rot.

i am no master grower, and i am always learning new things each grow but the suggestions above have helped me get to where i am now in terms of my hydro setup.

simple nutrient programs i can suggest:
jacks hydro - start with the jacks 3:2:1 recipe, it can be found by googling. incredibly cheap and simple.
megacrop - a friend is using this simple 1 part with great success. incredibly cheap and simple. it's literally a one-part powder. smells god awful though!
veg+bloom - more expensive than the powders above, but still quite inexpensive compared to a lot of others. working well for me so far. see the thread on ic for lots of info. dansbuds specifically has been a lot of help for me personally with veg+bloom, so look for his posts.

do you have any pictures of the plants from last run? was yield just poor but quality was fine, or did the plants look a bit rough as well?

Click to expand...

No, I appreciate the feedback, and dont feel as if you are, I came on here for a reason and was as honest as I could be about what i used, how it turned out etc, I never expected to have a perfect result my first time around with hydro, there's always a learning curve lol

I'm not sure what VPD stands for tbh, well that is until you mentioned it, spent some time reading and unless im somehow way off base you're speaking of vapor pressure deficit, found a very informing and well written post, on this site for that matter https://www.icmag.com/ic/showthread.php?t=153547

after reading about it all, can definitely say, non issue.. daytime temp/humidity in my room is 79-81f @ 55%rh, nightime being 77-79f @ 58%rh... the environment of my room is a non issue, its very stable, and right where it should be


And you as well as pretty much everyone else who has replied have confirmed exactly what i thought in the first place, the way the plants were trained/lollipopped, was simply not sufficient, as well as the semi organic nutes and high ppm were causing an issue in uptake.

will post some pics of plants, n no there were no health issues, immaculate really, i had fan leafs off pure indica's that were approaching a foot in length, base of stalks ~2"... guess i never included this part, there wasnt 8 plants in the room, even though there are 8 sites, (long story). 1/2lb a plant is no failure, quality is good, smell good, great trichome coverage/size. simply put tho, there is Much more to be had there and im after it.

Maxi-Bloom

Maxi-Bloom

Chemdawggy Dawg said:

Maxibloom is just the easiest and cheapest. If you do the things I just said you will get at least 5 or 6 on the next grow. I've ran those systems since 2011 so there's that. I like 68 because I've had my best grows there. I swear by the sm90 in the water it helps with nutrient uptake.

Click to expand...

I vote for Maxi-Bloom. Extremely nice results. I use it at one quarter the recommended dose, even on my seedlings. Quality stuff here.

when ppm is too high it can cause root burn and lock out of other nutes

I use ~ 200 during early veg, < 400 during mid veg- early flower, and max of 800 in full bloom

Nute issues aside, you went from 21 pots to 8 buckets. You don't need a 13 gal bucket per plant. 5 gal is plenty. Decrease bucket size and increase the number of buckets.

Your environment is spot on, and I know for a fact you can get 8 oz per plant in a 5 gal bucket with ease. 12 5 gal buckets and dial in your nutes and you will hit 6 lbs + with that setup, no problem

It sounds like you have a nice system, seems like you have plenty of oxygen going to the roots.

That high of ppm's can cause lock out and stunt growth. I would cut the ppm's/EC in half and see how a run goes. Personally I don't let mine get higher then 800ppms.

With RDWC once you get it dialed in it takes off, plants go wild..

so been a few weeks since ive updated anything here...

since last post i had my heatpump die which ive since replaced lol.

ended up buying a bluelab guardian connect trimeter, as well as the accompanying connect stick for pc, so will have a full data log of ec, ph and temp for all future grows.


have totally switched up all nutrients i was previously using, currently using (not 100% sure ill be staying with base nutrient line)

Cx hydroponics -> regen'a'root @ ~3ml/g
general hydro -> maxigro @ ~ 1tsp/g

botanicare -> calmag @ 2.5ml/g

sitting at ~ 550ppm at around a 5.5-6.0ph (still waiting on meter and only have a shit liquid test that is far from... Accurate)

learned since testing my water in various areas that my chiller reads high.. (set @ 66f, water was 58f!) have since adjusted to get water at 65-67f,

have also lowered water level to ~3-4" below bottom of netpots after new clones established roots beyond hydroton/netpot, still on the smaller side but some research into it supports what i was thinking that the hydroton remaining soaked all the time was a contributing factor to root rot. have also learned in the course of reading that in undercurrent systems that are "superairiated" eg, beyond 1.25lpm/G should reduce nutrient concentration even further... hoping to get some feedback from others on these things

oakley1984 said:

have also lowered water level to ~3-4" below bottom of netpots after new clones established roots beyond hydroton/netpot, still on the smaller side but some research into it supports what i was thinking that the hydroton remaining soaked all the time was a contributing factor to root rot.

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3"-4" is a good space. Sometimes root rot on clones can come from the plug the clone was started in. Rockwol will get too saturated many times, even peat plugs and soil can get soaked when the water level is high.