RDWC pH issue

[Stagetek]

I have a small RDWC grow going; entering the 8th week of flower. 4 Columbian Gold plants, in 20 L buckets and 1 CG in a 55 L tote. Plants are large and bushy; the one in a tote went there at flower as the roots were filling a 20 L bucket.

They all share a reservoir and total volume of the entire system is between 130 - 150L. I'm using AN Connoisseur with all the supplements, plus CalMag to boost RO water. My initial pH is high, usually 6.3 or so, within a day and a half it's at 5.8 and then falls rapidly into the low 4s. I'm using a commercial 17% potassium hydroxide pH UP and swings of 1.0/day are the norm. Recently some of my fan leaves have started showing signs of what looks like a potassium deficiency, with dry brown tips and margins.

In case my plummeting pH was caused by root rot (despite a clean smelling res) I recently changed the res, using Conny A & B, Big Bud, Hygrozyme, Bud Candy and H2O2. Same nute drop as ususal. The plants look fairly healthy with good cola development and lots of trichomes. Pictures can be seen here:

http://s913.photobucket.com/albums/ac338/stagetek/CG/

I have a SCROG grow of Kandy Kush, in a similar RDWC system, 4 weeks behind this one. The same pH drop occurs, but starts much later in the week, and the wide swing is usually only days 6 & 7. Clean smelling res; pictures here:

http://s913.photobucket.com/albums/ac338/stagetek/KandyKush SCROG/

Getting used to RO water has been interesting, although the addition of CalMag has helped immensely. I'm coming to understand that this type of problem is fairly common in the various types of DWC, and the causes vary. Rather than a root zone issue though, I'm wondering if the cause is the relatively small reservoir given the plant size? Columbian Gold drink huge amounts of CalMag and are quick to show a deficiency, or, recover from one. Could this just be a similarly huge appetite for potassium, given that there does not appear to be wide spectrum nute lock-out?

Has anyone else had similar issues in a DWC system; and, if so, were you able to solve them? Similarly, has anyone noticed similar issues with World of Seeds Columbian Gold?

 

[Haps]

My water in my tidal systems is similar. I fixed it years ago by not adjusting my addback, I leave it at a high ph, and it balances the lower ph in the system. Regular res changes also help.

 

[thinkin]

Past grow, i have had the same PH dropping issue.

PH usually settles at 5.1 ph from 5.8-5.5

SWC. roots are super health. in fact everythings is in great shape.
tons of air, nice nutes.

I am writing it off as bacterial issue. Maybe light getting to rez?
also have a small gnat issue. I have no idea whats the cause. PITA!

cleaned the plants roots with water. cleaned the res with green house cleaner.
baked the hydroton. it came back. (head in palm)

not too much nutes. start with lucas change to Ha3d formula midway
happens with fresh nutes, old nutes, seriously diluted nutes..

DAILY practice: I am using 12.5% h2o2 (food grade) 2-3 ml per gallon mornin and evening. keeps the PH steady. I could add more but, i dont want to risk root damage. Last weeks so i willing to suffer thru the extra work.

 

[Stagetek]

I don't adjust my top-up RO; it just can't bring pH back into range from 4.2.

Using full AN recipe with lots of organics; other than the rinse, no H2O2. You can see a rootshot from this week, in the KandyKush pix. The tan color is from additives, everything smells nice, as does the res, (2) 6" can/fan systems can't deal with the odor, nor can the huge air cleaner on the furnace, and usually either system is plenty, so I figure it's healthy.

The idea that it may be the potassium being insufficient is a dx of elimination.

 

[superusa]

I have a small RDWC grow going; entering the 8th week of flower. 4 Columbian Gold plants, in 20 L buckets and 1 CG in a 55 L tote. Plants are large and bushy; the one in a tote went there at flower as the roots were filling a 20 L bucket.

They all share a reservoir and total volume of the entire system is between 130 - 150L. I'm using AN Connoisseur with all the supplements, plus CalMag to boost RO water. My initial pH is high, usually 6.3 or so, within a day and a half it's at 5.8 and then falls rapidly into the low 4s. I'm using a commercial 17% potassium hydroxide pH UP and swings of 1.0/day are the norm. Recently some of my fan leaves have started showing signs of what looks like a potassium deficiency, with dry brown tips and margins.

In case my plummeting pH was caused by root rot (despite a clean smelling res) I recently changed the res, using Conny A & B, Big Bud, Hygrozyme, Bud Candy and H2O2. Same nute drop as ususal. The plants look fairly healthy with good cola development and lots of trichomes. Pictures can be seen here:

http://s913.photobucket.com/albums/ac338/stagetek/CG/

I have a SCROG grow of Kandy Kush, in a similar RDWC system, 4 weeks behind this one. The same pH drop occurs, but starts much later in the week, and the wide swing is usually only days 6 & 7. Clean smelling res; pictures here:

http://s913.photobucket.com/albums/ac338/stagetek/KandyKush SCROG/

Getting used to RO water has been interesting, although the addition of CalMag has helped immensely. I'm coming to understand that this type of problem is fairly common in the various types of DWC, and the causes vary. Rather than a root zone issue though, I'm wondering if the cause is the relatively small reservoir given the plant size? Columbian Gold drink huge amounts of CalMag and are quick to show a deficiency, or, recover from one. Could this just be a similarly huge appetite for potassium, given that there does not appear to be wide spectrum nute lock-out?

Has anyone else had similar issues in a DWC system; and, if so, were you able to solve them? Similarly, has anyone noticed similar issues with World of Seeds Columbian Gold?

I would drop the bud candy and flush with florashield or physan 20 if you think it is res related. Sugars in DWC = no no (IMO). BTW using RO water proved to be more trouble than its worth to me. If you live in the city and you have municipal water that is decent (especially around or less 200-250 ppm @.7), i would use it instead of the RO + calmag.

 

[Stagetek]

City switched from chlorine to chloramine; ppm is around 200, but pH runs 8.0 to a bit over 9.0. RO makes things a lot easier.

 

[jm420]

hygrozyme sucks

 

[ranta]

i agree with jm420 , hygrozyme of any kind sucs

 

[Stagetek]

If I need a 'trash the product' thread, I'll ask for comments on AN, as that seems a reliable way to stir up the peanut gallery. Whether or not a given product 'sucks' (the Big One, or anything else for that matter) unfortunately, has little relevance. Hygrozyme sucks BECAUSE ...., may at least be pertinent. Kinda reminds me of concert gear coming off the road tagged NFG (No Fucking Good); really didn't help the techs, but hey it's an hourly shop rate.

What I need is some input on why healthy looking plants, in a clean smelling res, with healthy looking roots, have pH that is dropping like a stone, while solution strength stays relatively stable. 10 - 20 L of solution are being used daily. There is currently a similar thread in this category and it seems to crop up a few times a year in similar forums.

To reiterate, RDWC, total volume 150L or less, Columbian Gold in 8th week of flower. 4' tall plants. AN nutes as well as additives. After 2nd day pH swings by 1.0 or more, regardless of whether base nutes are pH buffered or not. Same issue has occurred in both tap water and RO water.

 

[tjo]

Has anyone else had similar issues in a DWC system; and, if so, were you able to solve them? Similarly, has anyone noticed similar issues with World of Seeds Columbian Gold?

me.. ihad this problem in my previous grows in rdwc.
i have RO water and i solve the problem adding 1/10 tap water!