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ph rapidly dropping ppm stays the same?

turbolaser4528

Active member
Veteran
I have been having this problem for some a good month with my 2 nycd x g13 from Soma in a 31 gallon rubbermaid, DWC gh nutes, lucas formula, 400w hps, in a wooden armoire, temps stay between 70-85 and rh is 40-60 %.

The ph just keeps dropping, I flushed with plain tap water (~130 ppm) for a good 8-10 days and the ph would just keep dropping to like 3.8-4.3. ppm would stay about the same maybe drop a little. But it didnt go up, ph never goes up in my setup. Maybe I am undernuting? I have kept the ppm at around 700-800 on a .7 conversion. I have an expensive hanna meter thats calibrated so I know my readings are pretty accurate.

I read somewhere that maybe its because I don't have enough nutes that the ph is so unstable? What fools me is that the tips of the leaves are burnt, much like nute burn, but when i flush and flush the plant doesn't dump anything major back into the res.


Sorry if this is posted in the wrong section, just don't know what to do, so frustrating. Also, both plants are almost 4 feet tall, vegged for ~30 days under a 125 500k cfl, in about week 8 of flower. Some of the leaves are starting to turn pale yellow like they are lacking nitrogen (from the flush i guess) but im scared to add nutes as they already show symtoms of nute burn (burnt tips, edges, stunted growth) maybe this is a deficiency?

any help would be appreciated, sorry for the lengthy post, and i did search a good deal. :puppydoge
 
C

cyberwax

Are you using ro water? If so the carbon hardness of your water is probably too low as the plant exchange one part mineral for one part acid when growing alot/budding.(usually from 2 weeks into flowering and onwards)

If possible i would suggest using some parts tap water in the mix to raise the buffer, ph up usually doesnt contain any buffering, unless you get some sort of ph+/kh+ additive. I know some aquarium stores sell em. But as said the easiest way is to just add some parts tapwater and rest ro, if tapwater is useless for the purpose then i would suggest either ph+/kh+ or just find some gh or kh salt.
 

10k

burnt out og'er
Veteran
Are you using GH Flora micro for hard water ? If so...that's the problem !

The micro for hard water you need to premix in a holding drum and wait a couple days to see if you need to pH it, otherwise if you pH it the day you mixed it, it will not hold that pH worth a damn, instead it will drop way out of range like an anvil over the next day or two. Or better yet, get rid of the hard water micro and get the regular GH flora micro.

Here's what Lucas had to say about it...
One tip - do not pH down this stuff, the hard water micro will drop pH gradually over the next 24 hours, for example I mix up a batch, it is at like 6.2, the next day, its at 5.6-5.8 after running in the system for a while. If I pH downed that to 5.7 before putting it in the system, it ended up as low as 4.8-5.2 by the next day. My conclusion, the hard water micro was buffering the alkaline crud in my water, it just does not do it ASAP fast like the phosphoric acid.

hth,
10k
 

Blunt_69

the keeper of the creeper
Veteran
Nothing describes it like a picture. Lets see it..

I would try some RO water if your city water ppm is that high, it may be effecting your PH. Generally with lucase your PH sits 5.8 to 6.0.. If it is dropping means there is to much Nutrients, your girls are uptaking more water. Try a lighter mixture of 5 micro 10 bloom per gallon.dont adjust the ppm just run with it. .5 conversion should be around 600ppm
 

Hydro-Soil

Active member
Veteran
Two things will drop pH fast in DWC, root rot from res temps over 68F and root rot from not enough dissolved oxygen.

You should have at least 1 watt of airpump power per gallon of water.

Keep your res temp as close to 65F as possible and between 65F and 68F. With additional oxygen you can go with higher res temps but the noise is increased as well.

If you live in an area where it gets to 90F and above, you would probably save yourself a lot of headaches, time and money if you switched to drip or E&F. (Edit: I've used DWC/SWC for years in desert environments and finally switched. Sweeeeet Relief!)
 

turbolaser4528

Active member
Veteran
thanks for the help guys, I am using gh hardwater micro mixed with the regular micro. I will stop using the hardwater micro, and that should help keep my ph stable right?

Res temps never get above 74*F usually they are at about 68-69*F and I am using a silent air x5 air pump (its only 6 watts YIKES!) BUT my roots are healthy as can be, no root rot they are nice and white and clean, and i have a 450 gph pump on a digital timer to keep the 31 gallon res churning (4 mins on, 10 off)


I am not using RO, like i said its tap and its ~130ppm.

I dont have a camera otherwise I would post pics, also I am on a .7 conversion with my meter, what the 5/10 ratio equate to ppm wise? ~900?


Right now I checked my res and the ppm stayed at 800 but the ph dropped from 5.81 to 5.57 since this morning. HOWEVER, I did add 35 ml of hardwater micro and 70 ml of gh bloom, maybe that caused the ppm drop?


Thanks for the help, i will only use the regular gh micro, and keep you all updated. Id post pics if I could. :bigeye:
 

turbolaser4528

Active member
Veteran
UPDATE: Ok guy so my veg bubble bucket is staying rock steady with a ph of 6.09 and a ppm of ~900. Plants are 2 white widow x indica bagseed crosses in about day 30 of veg, in a small 3 gallon dwc.

So the lucas formula is working well for me now, I was undernuting them and that was my problem, bumped it up to 900 and they look very healthy.

The main plants in the flowering chamber, the ph is falling about .6 each day, and the ppm is rising about 30 each day. Is this within reason?

It seems with a ppm of 1080 it was too strong for them which is reasonable, 950 or so seems like it would suit them better, i shall give them that for their final week or so of flowering.


Thanks for your guidance everyone I can't wait to throw some harvest pics up here, and yiled huge on my next batch now that I know what I'm doing better!!!!!:joint:
 

Hydro-Soil

Active member
Veteran
The main plants in the flowering chamber, the ph is falling about .6 each day, and the ppm is rising about 30 each day. Is this within reason?
Yes... You're going to see it swing a bit but nothing out of normal ranges.

Just top off with RO water and bump the ppm back to 900-950 about once a week and you're solid.
 

Standaman

Member
Hey hydro-Soil i just read what you said about Res temps mine are up i have got them down a bit today by swapping my airstones there are two per pot and lots of bubbles now

My air pump is a 10w/10L per min. Should i go bigger to compensate?

Thanks
 

Technique

Active member
I'm having a similar problem here. running a 4 tub 8 Plant recirculating dwc.

Ec of our tap water is .1 Ph is around 7
Nutrient mix of canna Vega is around 1.8ec ph starts on around 5.3-5.6
Ph keeps dropping every day! i'm leaning more towards some fungal problem..

since i am also running one plant in its own non recirculating dwc with a Canna mix ec of 2.0 and ph will stay on 5.4 with only a small variation.

should we try for some h2oh to try flush out the problem?
 

Standaman

Member
My PH swings from 5.5-6.5 i just use a lil PH down but i'm gonna flush it in a bit and start again, i just cant take the risk, i have read not to be too anal about PH swings in veg but i find my self stuck between right and wrong. But its all good fun
 

Hydro-Soil

Active member
Veteran
Hey hydro-Soil i just read what you said about Res temps mine are up i have got them down a bit today by swapping my airstones there are two per pot and lots of bubbles now

My air pump is a 10w/10L per min. Should i go bigger to compensate?

Thanks
You have a 10 watt airpump? I wouldn't use a res size any larger than 10 gallons. 7-8 gallons if you have higher temps.

It's 1 watt of airpump per gallon of water but I'd go as high as 1.5w/gallon in warm areas of the country.
 

Standaman

Member
Well my total water in the system is 80 litres the pump i'm considering is a 38w/84L per min
maybe a bit too big but i'm thinking as the roots get bigger it wouldn't be a bad thing
 

turbolaser4528

Active member
Veteran
thanks again for the help, you guys are great :D

I got this lucas thing down, stopped using the hardwater micro, switched to the regular micro and I have no more problems, ph stays very stable:woohoo:

Just bought the eco plus 3 commercial air pump its 36watts/~80lpm, should be good for a 30 gallon res with 68 degree water temps right?


Will post results of my final yield in about a week. take care all:joint:
 

Hydro-Soil

Active member
Veteran
thanks again for the help, you guys are great :D

I got this lucas thing down, stopped using the hardwater micro, switched to the regular micro and I have no more problems, ph stays very stable:woohoo:

Just bought the eco plus 3 commercial air pump its 36watts/~80lpm, should be good for a 30 gallon res with 68 degree water temps right?


Will post results of my final yield in about a week. take care all:joint:
AWESOME!!! So glad things are back on track for ya. Go You!

Yes, that pump should be excellent ;)
 

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