Difficulty in stabilising ph in grow wool. Any tips please

I bought a 13.5 kg bag of grow wool. I purchased a 40 l plastic laundry tub. I then fill it with water and PH it down to 5.5. Then to leave the grow wool to soak and drain over 24 hours. I've repeated this roughly four or five times in that 24 hours hoping to flush the lime. Still hasn't stabilised. I now have it sitting in the bucket without water drying. I will then repeat process again. Any tips from experienced growers please.

Never had this issue, always used r/o water and pH stays stable. R/O is stable and super clean, making hydro predictable and simple.

What pH is your starting water and what are you using to drop the pH?

I have used Grodan Rockwool grow cubes (1 cm cubes) for 17 years now. for the first six years the rockwool was used straight out of the bag and had water added for the first time during the transplant.
The plants all thrived without difficulty but after six years I got convinced to rinse the cubes first.

So now I pH water to 5.0 and soak the cubes for ten minutes and drain. The the cubes are rinsed twice with a 50% general purpose nutrient mix.
Then the transplant is made.

The plants grew the same the first six years as they do now even with all the extra steps. Just putting the sprouts in a wet media rather than a dry one should have made a difference, never mind the pH, but no, the plants rooted and grew the same.

I can rationalize this in many ways, but the initial conditions only last until the very first watering and the plants do not react fast enough for this to make a difference.
Works for me, but I still do the rinse, makes it easier to put the new plant firmly in place.

I think next time I will buy the cm gro dan cubes. The rock wool premium Floc doesn't *look* like it has airration as good as gro dan cubes.

I've been using tap water, it comes out naturally at a ph of 7.2. I've been using ph down brand name nf nutrifield.

From what I've heard and what I will do in future is use R. O water and get some gro dan cubes. The lime in the bag of grow wool must be heavy. The amount of times having to drain and replace 5.5 water and repeat isn't ideal.

Thank you both for your feedback.

7.2pH? Niiiice water supply.

Your r/o filter will last a long time, I'm guessing the ppm/ec is very low as well.

Gro-wool is unrefined. Lower your ph soak to 3.0-3.5 and soak for a couple days. That should do the trick.

Razza586 said:

I bought a 13.5 kg bag of grow wool. I purchased a 40 l plastic laundry tub. I then fill it with water and PH it down to 5.5. Then to leave the grow wool to soak and drain over 24 hours. I've repeated this roughly four or five times in that 24 hours hoping to flush the lime. Still hasn't stabilised. I now have it sitting in the bucket without water drying. I will then repeat process again. Any tips from experienced growers please.

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Try soaking it in ph 5.1 water. If the water is hard make sure to adjust for the upswing.

Shouldnt take very long. I just pour through the croutons and perlite mixture. After that first ph 5.1 i use 5.5

Are you useing horticultural rockwool? You said grow wool but just check.

You can buy rockwool treatment but i just use solution thats ph 5.1 for the first. The constant 5.5 should keep it good.

Poke around gro dans site. Helpful in learning to use rockwool.

Are you using flock? The loose wool? Its kinda greebly, i prefer the 1/2" little croutons

Razza586 said:

I think next time I will buy the cm gro dan cubes. The rock wool premium Floc doesn't *look* like it has airration as good as gro dan cubes.

I've been using tap water, it comes out naturally at a ph of 7.2. I've been using ph down brand name nf nutrifield.

From what I've heard and what I will do in future is use R. O water and get some gro dan cubes. The lime in the bag of grow wool must be heavy. The amount of times having to drain and replace 5.5 water and repeat isn't ideal.

Thank you both for your feedback.

Click to expand...

Yes cubes work great, even better when mixed with perlite.

https://www.icmag.com/ic/showpost.php?p=7793875&postcount=31

Heres a post of mine about the matter. In the same thread someome posted showing how well flock works, better than strait perlite actually.

So whats your starting ec of the water? If you have hard water but dont account for the upswing theres the problem right there. It will be a problem in rockwool unless you account for the upswing from the hard water

This is the way to go. Ta m8