One thing I am stuggling with...

[jemro86]

So, after my first grow in DWC using 5 gallon buckets, I built myself a RWDWC, mainly inspired by Gary at PAHydroponics. The only difference is I couldnt fit my reservoir on the side of my tent, so I had to customize the PVC/bulkheads so the res sits in front of the tent. The buckets are 8 gallon black buckets. This is in a 4x4 tent. I also have a 2x4 tent, and I built the same kind of RWDWC, but just 2 buckets + 1 res.

I have a 1/4 HP chiller on the 4x4 tent, and a 1/10 HP chiller on the 2x4 tent. Water temps are 68-70. Day temps are 78-82, and the last few weeks I was struggling with humidity because where I am, the ambient humidity was over 80%. Now its finally leveled out, I am on week 5 of flower, and got the humidity down to 45%. Night temps are 66-68.

I was using a 400 GPH pump on both systems to re-circulate, but just upgraded to a 1100 GPH on the 4x4 tent. I was originally using 2 35 65L/min watt air pumps on the 2x4 tent, and a 110L/min air pump on the 4x4. I wasnt using air stones, I was using DIY air diffusers made from 1/4" porous soaker tubing.

I was struggling HARD with PH issues, like it dropping by over 1 a day. I was getting so frustrated. All my research led me to think it was one of 3 things. Too high of PPM/EC, root rot, or too much air pumping in CO2, causing the "acid rain" effect.

Coming from just DWC buckets where I ran easy 800+ ppm's with no issues, I started my dosing at around 50% of GH's trio chart for RDWC. Id end up around 800-900ish PPMs @ .5 scale. My plants showed no signs of nute burn, so I didnt think that was the issue. So I tried dosing UCRoots for 24 hours (with the chiller, i also run hydroguard and great white), so I am not running a "sterile" system. Ran the UCRoots for 24 hours at 7ml/gallon, drained and refilled, with a little lower PPM, around 600. Had the same issue. So now it was either too much air being pumped in, or too high nutes.

After reading through some threads here (some 17 pages long, lol), I came to the conclusion I would try to remove the air pumps. Between the "waterfall" from everything being recirculated, and I also added a 550 GPH pump into the res bucket with a few inch long tubing and a "T" connector at the end, to create another "waterfall effect" to go on in the res, as well as keeping the res circulated a bit better. Still had the same PH drop. But not as bad this time, as my PPM's were lowered to around 400-500 this time.

Last night was the first time I had a 100% stable PH in the 2x4. I did a res change yesterday, and after everything the PPMs were around 360. Forgot to mention I use RO water at around 15PPM's. My tap water is around 450, so I dont think tap is really viable for me to use. But my 4x4 dropped a bit - but not nearly as much, as the PPMs were around 470. Lowered it to around 370 tonight, and set PH to 5.8, so I am hoping for the best tomorrow.

Really the thing I am struggling to get my head around is how low you run PPM's in a RWDWC. Im guessing it is because there is more water being constantly circulated around, keeping the nute mixture "fresh", so you dont have to add as much? Idk if anyone has a better explanation then that, but I would be all ears! lol.

Here are some pics of my system in the 4x4 :) I am using Geeklight LED's, with UV-A/IR, and have California Sunworks UV-B I will be using shortly, in both my tents. The 4x4 has a 480 watt & 240 watt & 2 UV-B Lamps, and the 2x4 has a 240 & 120 & 1 UV-b Lamp. PPFD I just raised a bit (measured with my Hydrofarm PAR Reader) to around 800ish, in week 5 of flower.

The 4x4 tent is Zkittlez from Nirvana, and the 2x4 is Gelato from Nirvana.

 

[cemchris]

did the ppm's go up when the ph dropped?

 

[jemro86]

did the ppm's go up when the ph dropped?

Slightly, yes, and even more after adding in massive amounts of PH UP to stabilize it. Tonight was actually the first time (that I remember/have recorded) that the PPM's dropped by about 10 and the PH remained stable for 24 hours (in the 2x4).

 

[cemchris]

Slightly, yes, and even more after adding in massive amounts of PH UP to stabilize it. Tonight was actually the first time (that I remember/have recorded) that the PPM's dropped by about 10 and the PH remained stable for 24 hours (in the 2x4).

If the ppm's were rising and the PH was falling that usually means they are drinking water and not nutes. Either enviro or too high. Other hardcore DWC dudes can prob chime in on this with a little better understanding since im not a DWC dude but big on recirc hydro ( no air pumps)

Yeah PH up/down will spike your ppm some. Always remember that if having to adjust daily.

 

[jemro86]

If the ppm's were rising and the PH was falling that usually means they are drinking water and not nutes. Either enviro or too high. Other hardcore DWC dudes can prob chime in on this with a little better understanding since im not a DWC dude but big on recirc hydro ( no air pumps)

Yeah PH up/down will spike your ppm some. Always remember that if having to adjust daily.

My set up is now not using any air pumps. Just a recirculating waterfall, and another pump making another "waterfall" in the res. Everything between all the buckets is being recirculated.

 

[Roadblock]

In my diy rdwc they dont like over 500ppm at all, I have two side be side rooms and pushed one side to 650-700 ppm 4th week into flower and over 4 days the pistils were browning off and growth seemed to stall, Ive lowed the ppm to 400 and they are happier will have to see how they go now after the set back, all other values were spot on .

The other room has never been over 450 ppm and they are perfect at the 4th week flower.

While I was having problems with the stalled growth and browning pistils I read a guys email from Current Culture regarding the same issues I was having and they told him the EC was too high at 650 and to drop by 25% , they said the more aeration of the system the ppms need to be lower, has to do with the availability being much higher and so the ppms need to be lower to avoid burn or lockout .

This was very helpful for me and connected a lot of dots .

https://cch2o.com/troubleshooting-guide/

 

[Roadblock]

Here is the thread that got me looking at ppms in these systems, what was happening to this guy was happening to me and I can only put it down to the ppms being too high, what a difference 200ppm is showing on the plants going from 600-700 to 400 , I think the key to this is how much circulation and how much aeration you have, I got a lot of both and so must have low ppms if I want happy plants.

Ok cant post link so here is the most telling bit of the thread.

I just re-emailed them again today kind of beating a dead horse and this was the reply

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"
The brand of Cal-Mag you are using is not going to make a huge difference.


The only thing we suggest is to use the Cal-Mag with the lowest possible nitrogen.


You should use 1/4 mL/gal in veg, 1 ml in flower. That is only in cases where you are using R.O.


Your aeration levels versus the higher than recommended levels of nutrient for that aeration level IS what has been causing your issues.


Please continue to follow the recommendations as stated in the last e-mail.


Your overall PPM's should not exceed for any reason the levels that we are suggesting on the High Yield feed chart.


But cut back 25% from there (High Yield #'s) for optimal performance with the aeration level that you have been providing AFTER taking the extra pumps off.


That is an over-all PPM. That is with every product in solution.


From the details that you have given me, there is absolutely no reason to go for Cal/Mag deficiency.


You are a very meticulous man and I respect that.


Please apply the detail-oriented, meticulous nature of your thought process to trying to understand and follow directions.


I feel as though I have been fairly clear. Let me know if I can provide further assistance.


And please be in touch if/when more things develop. We cannot help with things we are not aware of.


-Kevin Hill, CCH2O Sales"

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"
P.S.


Always check their aeration if they are saying your PPM's are too low.


I hear of people running extra high PPM's but they also fail to mention that they drastically reduced or completely took off their stock aeration system.


Obviously, this will affect uptake and they will be running a completely different system than the one we are giving tech advice on.


So I would always suggest trying the out-of-the-box aeration, directions, and feedchart just once as a scientific control before branching out.


It is a Proven Production system for growth that has worked as-is with no changes for thousands of people who are getting great yields and amazing results.


-KH"