Combating RDWC nutrient depletion and build up.....

R

RCJR

Active Member
Ive been battling issues in my rdwc systems grows for years. Im currently using jacks321 formula with on going issues. I was shown this article
https://manicbotanix.com/rtwdtw-hydroponic-growing-systems-v-recycling-systems/
that talks about in a recycling system (rdwc,dwc) the plants uptake npk & manganese within hours and the slower uptake nutrients build up as the water is taken up by the plants. Leaving you deficient in npk & mn but an excess in others. The rule of thumb for rdwc is doing a weekly water changes but within the first day the npk & mn is greatly depreciated leaving the plants hungry for it throughout the rest of the week until the next nute change. How could we fix this?

1.)Complete res change every other day?
2.)Adding fresh water thoughout the week to dilute the slower uptake nutes?
3.)Adding small amounts of pre mixed nutes as the water drops throughout the week? But wouldn't this just make the build up of the slower uptake nutes worse?

Please only RDWC or DWC growers chime in. Drain to waste is different because your not recycling old nutes to the plant constantly throughout the week.
 
9

93OG

Well-Known Member
what are your ppms doing? Are they dropping at first then climbing as your plants use water? Do they constantly rise? What’s your ppms?
 
R

RCJR

Active Member
93OG said:
what are your ppms doing? Are they dropping at first then climbing as your plants use water? Do they constantly rise? What’s your ppms?
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They stay about the same as the water drops or slightly decreases, but that could be from npk&mn depleting and other slower uptake nutes building up as the water drops.
 
9

93OG

Well-Known Member
That’s what you want. If my ppms stay about the same I don’t touch it. Sometimes all week except for ph adjustments. Are your plants looking underfed?
 
myke

myke

Well-Known Member
There’s a guy in that thread called aqua man. Search his posts. Lots of good info.
 
ҖҗlegilizeitҗҖ

ҖҗlegilizeitҗҖ

Well-Known Member
RCJR said:
Ive been battling issues in my rdwc systems grows for years. Im currently using jacks321 formula with on going issues. I was shown this article
https://manicbotanix.com/rtwdtw-hydroponic-growing-systems-v-recycling-systems/
that talks about in a recycling system (rdwc,dwc) the plants uptake npk & manganese within hours and the slower uptake nutrients build up as the water is taken up by the plants. Leaving you deficient in npk & mn but an excess in others. The rule of thumb for rdwc is doing a weekly water changes but within the first day the npk & mn is greatly depreciated leaving the plants hungry for it throughout the rest of the week until the next nute change. How could we fix this?

1.)Complete res change every other day?
2.)Adding fresh water thoughout the week to dilute the slower uptake nutes?
3.)Adding small amounts of pre mixed nutes as the water drops throughout the week? But wouldn't this just make the build up of the slower uptake nutes worse?

Please only RDWC or DWC growers chime in. Drain to waste is different because your not recycling old nutes to the plant constantly throughout the week.
Click to expand...
Psh you worry too much haha
I hate to say it, but thats dumb.
I am not going to just throw out my water everytime it cycles once like this article suggests, there goes all the profits for a marginally healthier plant.

There is a reason people usually don't constantly fight toxicity and deficiency at the same time, and also that hydroponics grow the biggest plants the fastest.
There is plenty enough N in my solution after 7 days, that doing a rez change once a week is plenty enough.
 
R

RCJR

Active Member
myke said:
https://www.rollitup.org/t/can-someone-explain-to-me-how-to-top-up-a-reservoir-rez-i-just-dont-get-it.428476/page-2#post-15245286

good read here.
#3 for the win!
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so i made myself this chart to follow according to that thread. Is this correct?

20 gallon RDWC res

20 gallon res change with fresh water and nutes to the desired EC range (1.2 EC at ph of 5.8 )

Wait a day or 2 until the water level drops (ideally the EC should be 1.2 or 1.3 at this point)

Make a 33% solution (.4 EC) in separate container and add back until the res is full again (i don't have a way to see exactly how many gallons the res is low so ill make more than what i think it will take)

Once the res is topped off with this 33% solution and the EC is at the target range of 1.2 (at 5.8 ). Your nutes are dialed in.

If the EC is higher than 1.2 (at 5.8 ) after the 33% top off your target EC needs to be lower

If the EC is lower than 1.2 (at 5.8 ) after the 33% top off your target EC needs to be higher

Don't increase or decrease more than 20%at a time

After you have filled the system with 20 gallons of top off solution it's time for a complete res change
 
myke

myke

Well-Known Member
RCJR said:
so i made myself this chart to follow according to that thread. Is this correct?

20 gallon RDWC res

20 gallon res change with fresh water and nutes to the desired EC range (1.2 EC at ph of 5.8 )

Wait a day or 2 until the water level drops (ideally the EC should be 1.2 or 1.3 at this point)

Make a 33% solution (.4 EC) in separate container and add back until the res is full again (i don't have a way to see exactly how many gallons the res is low so ill make more than what i think it will take)

Once the res is topped off with this 33% solution and the EC is at the target range of 1.2 (at 5.8 ). Your nutes are dialed in.

If the EC is higher than 1.2 (at 5.8 ) after the 33% top off your target EC needs to be lower

If the EC is lower than 1.2 (at 5.8 ) after the 33% top off your target EC needs to be higher

Don't increase or decrease more than 20%at a time

After you have filled the system with 20 gallons of top off solution it's time for a complete res change
Click to expand...
Only thing I would add is smoke a joint while mixing.Lol,sounds good ,its what i do.I dont fret over a point here or there.
Im not convinced this your problem though.Time will tell.
 
R

RCJR

Active Member
myke said:
Only thing I would add is smoke a joint while mixing.Lol,sounds good ,its what i do.I dont fret over a point here or there.
Im not convinced this your problem though.Time will tell.
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I've read that thread you posted a bunch of times but i still don't get how a 33% strength top up solution will bring an ec back up to the starting level no matter if you add 2 gallons or 10 to the res. But I'm going to give it a shot and see if it works.
 
myke

myke

Well-Known Member
RCJR said:
I've read that thread you posted a bunch of times but i still don't get how a 33% strength top up solution will bring an ec back up to the starting level no matter if you add 2 gallons or 10 to the res. But I'm going to give it a shot and see if it works.
Click to expand...
Lol,im no expert.I just top up sooner then later.If roots are submerged their happy.
 
R

RCJR

Active Member
myke said:
And always the same issue?
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Yep, slightly different but all relatively the same. The girls that are almost done didn't have too many issues in veg but when they got switched to flower it all started going south. The ones i just flipped yesterday had issues from day one but all the issues are yellowish and brown spots. Then in flower the leaves start to turn brittle. With this 33% thing i might be able to dial in the strength that they want and give them some npk& mn from the top offs throughout the week since i guess the plant uptakes those within the first few hours of a res change? I have been doing a res change and not adding anything for 7 days and letting the water drop.
 
myke

myke

Well-Known Member
RCJR said:
Yep, slightly different but all relatively the same. The girls that are almost done didn't have too many issues in veg but when they got switched to flower it all started going south. The ones i just flipped yesterday had issues from day one but all the issues are yellowish and brown spots. Then in flower the leaves start to turn brittle. With this 33% thing i might be able to dial in the strength that they want and give them some npk& mn from the top offs throughout the week since i guess the plant uptakes those within the first few hours of a res change? I have been doing a res change and not adding anything for 7 days and letting the water drop.
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So have you tweaked your Ca Mg at all?
 
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