Always feed heavier if ec drops?

D

DWCgrower406

Well-Known Member
Running rdwc, 4 plant 5x5, cultured solutions nutes, 1 week into flower, plants are happy. In the past ive always monitored ec to determine what plants want. If i feed and ec stays even over next few days, ec is perfect, if ec drops, they want it stronger, if it rises, ec is too high. Pretty common practice amd has always worked for me.
In this grow, the plants are asking for more and more based on ec falling. My system is 30gal, currently feeding about .9ec as reccomended in cs feeding chart. Within 24 hours they suck it down to about .6ec. In a 30gal res, thats a lot of nutes they are taking up. They are getting a bit of tip burn and some of them looking a bit darker green than they should. Definitely dont look hungry and even maybe slightly overfed, but still they suck that ec right down like they are starving and want higher concentration. For now ive just been replenishing enough to bring back up to .9 daily.

Should i follow the ec numbers and feed heavier until it stabilizes? Or feed less based on the darker green color of the plants and slight tip burn? I guess naturally the bloom nutes will be lighter in nitrogen so maybe don't need to worry about the dark green, but still the slight tip burn makes me hesitate to feed heavier.
 
OldMedUser

OldMedUser

Well-Known Member
The EC should never be stable and always dropping. That would indicate that the plants aren't eating anything if it's not going down. I've done a lot of DWC grows in Rubbermaid tubs and would first top up with RO water every 3 days then check the ppm and pH. The ppm would be down so I'd add small amounts of nutes to get back to my target range then wait a bit before checking pH. The pH would be up a bit so a few drops of conc. sulphuric acid would bring that down to around 5.5. Then I switched to pH Perfect AN nutes and forgot about pH.

One thing I noticed was that the ppm drop would go up to 4x faster once I flipped to flower then go back to pre-flower levels once stretch was over. Now I feed a heavy dose of nutes and bloom booster, Big Bud, a week before flipping and with a little added CO2 get explosive growth thru the stretch which is a huge growth spurt. By the end of stretch around 3 weeks in I got lots of golf ball sized buds all over the place.

Along with added CO2 I increase light levels and reset my temp controller to 90F max before the exhaust fan switches on to run at the redline for the stretch. Once that's over go back to 80F max, cut CO2 and switch feeding to Lucas Formula style to reduce N levels. Big Bud 'til the end of week 5 or 6 for something that finishes in 8 or 9 weeks. Stretch is about 40% of the total flowering period so goes say 3 weeks for an 8 week strain but longer for plants that take longer to finish.

:peace:
 
D

DWCgrower406

Well-Known Member
OldMedUser said:
The EC should never be stable and always dropping. That would indicate that the plants aren't eating anything if it's not going down. I've done a lot of DWC grows in Rubbermaid tubs and would first top up with RO water every 3 days then check the ppm and pH. The ppm would be down so I'd add small amounts of nutes to get back to my target range then wait a bit before checking pH. The pH would be up a bit so a few drops of conc. sulphuric acid would bring that down to around 5.5. Then I switched to pH Perfect AN nutes and forgot about pH.

One thing I noticed was that the ppm drop would go up to 4x faster once I flipped to flower then go back to pre-flower levels once stretch was over. Now I feed a heavy dose of nutes and bloom booster, Big Bud, a week before flipping and with a little added CO2 get explosive growth thru the stretch which is a huge growth spurt. By the end of stretch around 3 weeks in I got lots of golf ball sized buds all over the place.

Along with added CO2 I increase light levels and reset my temp controller to 90F max before the exhaust fan switches on to run at the redline for the stretch. Once that's over go back to 80F max, cut CO2 and switch feeding to Lucas Formula style to reduce N levels. Big Bud 'til the end of week 5 or 6 for something that finishes in 8 or 9 weeks. Stretch is about 40% of the total flowering period so goes say 3 weeks for an 8 week strain but longer for plants that take longer to finish.

:peace:
Click to expand...
Im running co2 as well, also i do have the ability to give a boost of light which they probably could use right now. Im running a 1000watt hps but my sealed hood has a second socket for running a 400watt mh next to it. Maybe ill fire that up during the stretch. They could use the broader spectrum anyway.
As for them not feeding if ppm stays level, not really the case. It means they are equally drinking water and feeding. If you start with 20 gallons of nutes at 400ppm and end with 10 gallons of nutes at 400ppm, that means half the nutes have been consumed and half the water has been consumed. If no nutes were consumed, ppm would double.

Edit: just thought about how you said that and realized you are referring to ppm levels if water level is kept full as they drink. In that case, yes ppm staying even means no feeding. When i say they are sucking down the ppm, im referring to ppm levels with no water top up. I do not have it currently set up with auto top up. I let them drink for a day and check ppm. Water level is down 4 or 5 gallons as well as ppm dropping dramatically which tells me they are eating more than drinking and want stronger mix, but im hesitant because of the slight tip burn and dark green leaves
 
Last edited:
GBAUTO

GBAUTO

Well-Known Member
Before I added a top-off rez this year to my 4-site UC style system, I would encounter the same situation.
40-gallon system would use 5-6 gallons/day and I would see some ec variations.
I run Jacks 3-2-1 @ 1.5ec throughout the grow and keep the top-off @ 1.0
I agree with you on using ec as a reference whether I'm feeding too much or too little.
I think that if you can keep a consistent level and the plants are happy, keep repeating...
 
OldMedUser

OldMedUser

Well-Known Member
DWCgrower406 said:
Edit: just thought about how you said that and realized you are referring to ppm levels if water level is kept full as they drink. In that case, yes ppm staying even means no feeding. When i say they are sucking down the ppm, im referring to ppm levels with no water top up. I do not have it currently set up with auto top up. I let them drink for a day and check ppm. Water level is down 4 or 5 gallons as well as ppm dropping dramatically which tells me they are eating more than drinking and want stronger mix, but im hesitant because of the slight tip burn and dark green leaves
Click to expand...
Yeah I always top up with just RO, let everything mix for 5 min or so then check ppm. I get what you mean about the EC being lower or higher before topping up and if a big drop then go higher EC after topup or visa versa if higher before topup. I should have a cahrt about that.

RH is important too and if chronically low you want a lower EC as they will pull up more nutes than they can use when drinking lots and then they store that in the leaves which leads to Toxic Salts Buildup or TSB. That usually rears it's ugly head about mid-flower then all the older leaves start going all yellow/brown and crispy. If bad the tiny bud leaves will be like that by harvest. Snap, crackle, pop when you smoke it.

I thought for ages I was overfeeding and ended up running my DWC around 500 - 600 max. Even in the summer I have problems keeping the RH up to 50% and in the winter it can 20% all the time. Sealed room is the way to go but that's extra cash I can't spare atm.

:peace:
 
Star Dog

Star Dog

Well-Known Member
I used aqua trays for a few years, I seen a stable ec as a sign of the perfect balance of water and nutrient being used?

I would alter to suit, hot weather required a lower ec to allow for the increased evaporation.
 
D

DWCgrower406

Well-Known Member
OldMedUser said:
Yeah I always top up with just RO, let everything mix for 5 min or so then check ppm. I get what you mean about the EC being lower or higher before topping up and if a big drop then go higher EC after topup or visa versa if higher before topup. I should have a cahrt about that.

RH is important too and if chronically low you want a lower EC as they will pull up more nutes than they can use when drinking lots and then they store that in the leaves which leads to Toxic Salts Buildup or TSB. That usually rears it's ugly head about mid-flower then all the older leaves start going all yellow/brown and crispy. If bad the tiny bud leaves will be like that by harvest. Snap, crackle, pop when you smoke it.

I thought for ages I was overfeeding and ended up running my DWC around 500 - 600 max. Even in the summer I have problems keeping the RH up to 50% and in the winter it can 20% all the time. Sealed room is the way to go but that's extra cash I can't spare atm.

:peace:
Click to expand...
Yep, i fought the humidity battle and eventually got sick of it. like you said, 20% in winter. I had a humidifier in my 5x5 room meant for a 2700 square foot area pumping 6 gallons of water into the air daily just to get the room up to a whopping 40-50rh which is still terrible. On top of that i had to run a heater in my room a lot of the time, even with lights on during night. i was probably spending 40 bucks a month extra in electricity just between heat and humidifier. Eventually i said screw this and went sealed. It was 160 bucks for an inkbird co2 controller which is actually pretty nice and has great reviews, 40 bucks for regulator, 140 for 20lb tank, like 20 bucks for the rest of the tubing and stuff. Like 350 bucks total and it was by far the fastest, easiest environmental control ive ever setup. Takes like 20 minutes to hook it all up and your done. Turn it on and forget about it. Now i can very easily control my temp and humidity to exactly what i want any time of year without ever running heat or humidifier. I do run a dehumidifier but kinda need that for flowering even not sealed. Definitely no regrets here going sealed. literally set your grow to the perfect vpd, not fight everything to just get as close as you can.
 
You must log in or register to reply here.
Top