pH bounce

[crisscross]

I can't keep a stable pH in my bucket. For the last 5 days I have been having trouble staying below 6.0. I can adjust the pH back to 5.2 and within 8 hours it's back up to 5.9 or 6.0. I am using RO water, maxibloom at 4g/3 gal, I have 363 ppm, a res that ranges between 78 and 82 degrees Fahrenheit and I am 31 days in from seed. I am doing a dwc bucket under a cfl for 24 hours of light and I am planning on switching on the hps this weekend (of course I will slowly lower the light over a few days not to burn the plant hopefully). The strain is albino rhino x big bud germinated in rockwool now in hydroton.

All of that being said why is the pH my res constantly climbing? I have 3 ideas:
a. unstable water--if that's even possible
b. it's a small res and that's the way it goes
c. the plant is hungry for more nutes? I thought Freezerboy said that the request for more food may cause the pH to rise.

any comments/suggestions are appreciated

 

[FreezerBoy]

You're witholding critical information. We need to know what the EC has done as well. One without the other is useless.

 

[HempAlchemist]

i think you nailed your answers. small buckets + fast growing plants = pH flux. hard to tell without pics, but to me, if you are about to put them into flowering i would have the ppm around 600-800. i think freezerboy's line is ppm down and pH up means you need to feed more. ppm up and pH down means you need to feed less. so what has your ppm been doing? ppm and pH should be noted at least once a day everyday. keep track of that and you will know exactly when your plants need more food. most importantly what are your plants telling you? do they look sick or yellow? how do your roots look, your rez is a lil warm. some pics would help a lot as well as more info on your grow, lights, fan, etc

sorry for repeating you FB, your post wasnt up when i started to write mine.

 

[FreezerBoy]

Sorry nothin'. Thank you.

EC and pH are Punch and Judy. They're a team, they work together. One without the other is useless.

Giving movement of both is troubleshooting 101, the equivalent of "is it plugged in?" EC and pH should move in opposite directions. If they don't, it could be an indication of trouble, big trouble. However, until we have both, we can't say.

 

[crisscross]

Sorry FB, I thought I was giving all of the required info in order to troubleshoot...guess it's a good thing that I started in the "new growers" forum. I bought a tds meter because I thought I "had to" have one. The funny thing is I test my water 3 times a day and record TDS but I have no idea what that information could be used for other than checking nute levels.

TDS has been climbing WITH pH--but gradually. The res started at 290 on the 11th, and as of right now it is 368 (the rise may be due to the ph down I have been using?) I have been doing 'add backs' while keeping ratios equal to the initial res fill. Also, the water I have been 'adding back' has been exceptionally low in pH (I added pH down) in order to counter the rising pH.

The plant is looking fantastic-I already started bending her. Roots look great, a little dirty I think from the nutes and or hydroton (I guess I should have washed it even MORE than I did). I really appreciate all the help.

 

[FreezerBoy]

Both climb? Hmmm...

Small tubs certainly swing faster. Aeration can raise pH by driving CO2 out of the water (which exists in the form of carbonic acid) but, I'd start with the RO and old nute solution.

RO is far less pH stable than tap. I'm having similar problems since moving. My old tap was 0.5 EC. The new stuff is less than 0.1. Most would think it a trade up but, when dealing with the change for the first time, it's a pain in the butt. Any reason you're not using tap? Hydro is hundreds of years old and one of it's first lessons was purified water was dead water not fit for plants.

I sometimes run a tank for a month or longer without flushing. Signs of unhappiness tell me when to drain and start over. Sounds like you've been running that tank for a while now and that everything was happy... until just recently. May be time for a change.

Remember that EC, "TDS" and "PPM" display gross conductivity. They say nothing about consumption of specific elements. Plants may not drink in the same proportions as you feed. Extreme example: Even though "TDS" is steady, for all you know, Nitrogen is now at toxic levels while Potash is lethally deficient.

On another note, "TDS" is another Punch and Judy. To be truly informative, "TDS" needs to be reconverted back into the original EC your pen measured. Somewhere on the pen or instructions you'll find a conversion number (most likely 500, 640, 650 or 700) you should list with the "TDS" reading. As in: 290@700 or 368@640. That or divide "TDS" by the conversion number. 290÷700= 0.4 mS/cm EC (or 414.3 µS/cm if you like bigger numbers)

 

[crisscross]

I'm using RO because I (again) 'thought' that I had to. I guess since I have a shit ton of it saved in the grow room I will mix 50/50 with tap until gone?

I flush once a week. I (once again) thought that I had to.

It's almost 5 am where I'm at and I don't have the instructions for the pen so I will have to wait until the store opens at 11. I will log on when I get home with more info but the website at HM Digital said that model AP-1 (mine) is at NaCl conversion factor of .5...therefore I should multiply by 2 to get my ec. I think I'm going to buy a ec meter if I don't get clear instructions from the guy at the store.

FB, one last thing: how the heck does a meter tell me which nutrients are being consumed and which ones are not? Oh, and what the heck does punch and Judy mean?

 

[FreezerBoy]

Only way I know to determine the proportion of nutes consumed is to send water to the lab, before and after, for chemical analysis. I'm not aware of a meter available at the hydro store which does this.

Punch and Judy are hand puppets and one of western societies longest running comedy teams. They've been "together" for hundreds of years. I suppose I could've said Batman and Robin but, they often work alone...

@ .5 conversion, "TDS"x2 gives EC in uS/cm (microseimens per centimeter). Perfectly acceptable. Most, however, measure EC in mS/cm (milliseimens per centimeter) which is "TDS"÷500. Example: 500"TDS"x2=1000 uS/cm, 500"TDS"÷500=1.0 mS/cm. As you can see, 1000µS=1mS just as 1000 millimeters=1 meter. I mention this as most growers seeing an EC higher than 2.0 shit their pants. Imagine if they saw 1,987.65 and didn't know to move the decimal 3 spots left?

290 "TDS"@.5 is 0.58 EC. My old tap water was 0.5. 0.58 sounds kinda low for a month old plant but with a cfl, your plants may just not be that hungry (big light makes for a big appetite and vice versa)

How big are your buckets? Is water surface exposed to evaporation of any kind?

 

[crisscross]

Bucket is 5 gallon normal bucket. I'm only doing one plant until I get the hang of it and then I will expand. I am going to try everything this first run and learn from IC and all of my mistakes. There is no water exposed. The pH finally stabilized last night. I did an add back of water with 20% more nutes than what I had previously put into the res in order to prepare the plant for the big light I'm turning on tomorrow. That's when the fun should begin.

Thank you for explaining the math behind EC and TDS. Not very difficult at all really, thanks.

The main reason I began with RO water was because of the idea put into my head that RO is the easiest water to use because it's almost like working with a clean canvas. I realize it is void of minerals but my tap has a ec of 1.1, or a TDS of 550 roughly. That's crap city water full of chlorine. I have an RO for drinking and cooking so I use it for this as well. If you have a better idea to water I am open ears but I don't know if you will considering my water is already crap to begin with.

 

[HempAlchemist]

grats on getting everything balanced. now just keep good notes about TDS and pH and you should be good. as far as your water goes, i would dilute it down with RO water to about 200-250ppm on your TDS. then let it sit out overnight and a good deal of the chlorine should have off gassed back into the air. that should help you keep the pH swings down to a min. good luck

 

[crisscross]

I've got 5 1 gallon containers that I am filling, then leaving open. Thanks for the tip HempAlchemist. Thank you to everyone who has helped me by sharing their experience and knowledge.

I have one question left (for today lol): my roots are a little tangled. I have 2 air stones in one bucket. Should I either
a. remove one stone or
b. untangle the roots or
c. both or
d. do nothing and keep going because everything looks good on top?

 

[FreezerBoy]

Unless it's a matter of transplanting, leave them be. If transplanting, consider cutting the airline where it enters the root mass and transplanting the now disconnected airstone along with the plant (tubing and stones are dirt cheap compared to your time, effort and hopeful yield)

I routinely, after harvest, perform airstonectomies, heaterectomies, pumpectomies to reclaim items swallowed by roots...

 

[crisscross]

FB HA thanks so much for your advice. I wish I could give you more rep than I already have. Thanks!!!!

 

[Rukind]

If ph is climbing, consider re mineralizing the ro water to make it more ph stable. You can do this by first starting off with potassium carbonate and citric acid. then just add your nutrients.

use about 363mg of potassium carbonate in your ro water first
then add citric acid to bring the ph back down to 6 or however you like it.

I have been doing this per gallon:

ro water
363mg of potassium carbonate
2.5ml of protekt (optional i suppose)
about 100 to 200mg of citric acid (the idea is to bring the ph down to 6)

at this point you can use your nutrient recipe (this is the one im using)
--------------------
5ml of gh micro
5ml of gh grow
7ml of gh bloom
5ml of cal mag+
.5g of empsom salt

Sometimes I change the amount of citric acid I use if I am adding phosphoric acid in later flowering.

ph doesn't really swing in my hempy buckets since I have been doing this. I used to have lots of problems with ph swings. I used tap water before this and my ppm was really high and i burned my plants.. then i used ro water and my ph was even less stable.

I also just dont like hempy buckets anymore.