What's new
  • Please note members who been with us for more than 10 years have been upgraded to "Veteran" status and will receive exclusive benefits. If you wish to find out more about this or support IcMag and get same benefits, check this thread here.
  • Important notice: ICMag's T.O.U. has been updated. Please review it here. For your convenience, it is also available in the main forum menu, under 'Quick Links"!

Stabilizing pH for multiple feeding

Hi guys, so I'm running a top feed watering system in rockwool. I would like to try and start feeding multiple times throughout the bloom phase.

Before I do, I would like to stabilize the res. I've noticed the pH would swing sometimes between 5.7-6.7. Most of the time it's at 6.4ish.

What would be the best option to keep it in range? It's for a 55gal res.


Thanks in advance!
 

Andyo

Active member
Veteran
Grodan rockwool PH control

Grodan rockwool PH control

I used to grow capsicum sweet peppers on a comercial scale
Grodan company used moniter my feeds and run off
They use a calcium nitrat /ammonium nitrat addition subtraction ladder for PH contrl
The reason it works is that as plants take up calcium nitrat the cause a rise to alkaline in the root zone and as they take up ammonium nitrate They root zone becomes more acid
in the correct ratio Ph of 6.0 to 6.2 can be achieved
They recomend 0.5 ppm to 1.5 ppm amonium nitrate.
Knowing the make up of your nutrient formula is needed
However i found a way that suited me when growing marijuana
making up a 3rd bottle A + B and 3rd bottle being UREA nitrogen a substitute for ammonium nitrate as ordering ammonium nitrate in many countrys is reportable as it can be used in bomb making !
The amount depends on the amount of calcium nitrate in your nutrient formula
unfortunatley marijuana nutrient companys hide this.
The best way would be disolve 1.5 grams of urea in 1 liter
And try slowly increasing amounts via syringe measurement with no acid used on a test plant of the same size and maturity as your crop.
I use a 0.00 gram scale cheap enough via the internet this would work well as you have a reasonable size rezevoir start with 0.05 g that was an average of 1 granule but they vary from 0.05 to 0.03 in weight .A
 
Last edited:

DrDee

Member
DirtyBirdy,
A swing (rise ) is common as nutrients are used up. So correct for the lowest desired level and allow a swing before correcting again. this is good for complete nutrient absorption.
JD
 
That's something, you using tap or RO, I wonder
I'm using about 75%ro and 25% tap water.
I read that it alhelps with stabilizing the pH swings. So far it has. I'll set the res to about 5.9-6.0ph, water my plants then check the next day and it's about 6.3-6.4pm(that's average).

I've read that the acceptable pH range for rockwool is between 5.8 and 6.2. I'm just scared if Im not monitoring it throughout the day, it might have a major swing.


If you put a tiny amount of Dolomite Lime in your reservoir it will act like a buffer. :tiphat:

The idea is to create a buffer and not put so much to raise the pH.

Try maybe 2 tablespoons worth and keep testing.

Reading this hopefully will explain you some more what to do:

https://www.maximumyield.com/managing-ph-in-aquaponic-systems/2/1208
Interesting. Ill give that link a look.
Thanks!

DirtyBirdy,
A swing (rise ) is common as nutrients are used up. So correct for the lowest desired level and allow a swing before correcting again. this is good for complete nutrient absorption.
JD

Are you referring to the res or root zone?
 

DrDee

Member
Are you referring to the res or root zone?

To the res...

You've seen those absorption charts? Hard to get optimal absorption of all nutrients at a single fixed ph. Whereas a rising ph will cover all those crucial nutrient uptake points.

Regarding your water...you want to make sure that that mix of RO and tap has enough Calcium and Mg...or that you are replacing it properly with a calmag product.

I wouldn't worry about the ph swing. Just renew and adjust daily.
JD
 

hush

Señor Member
Veteran
I let my gardens swing from about 5.5 up to about 6.5. It's good for the plants. I'm assuming that you are referring to a recirculating setup, because if your pH is swinging in a DTW setup then you have some strange buffering agents in the water. But yeah, if you are recirculating, then the swing is a natural effect, and a good one. Just re-adjust every few days or whatever. If that's a complication for you, then invest in a pH controller and peristaltic pumps to do the work for you.
 

Hydro8

Member
Before I do, I would like to stabilize the res. I've noticed the pH would swing sometimes between 5.7-6.7. Most of the time it's at 6.4ish.

That's a decent range IMO. At 6.7 I would do some PH down to about 6.3.

Don't chase PH and you will have a lot easier time, let it drift in a range. Most people stay in 5.5-6.5
 

Latest posts

Latest posts

Top