Cannot stabilize rockwool pH, please help!

[lightmove]

I have problems stabilizing the pH of runoff from my hydroponic garden.

The plants are young (4 weeks old). For now I use feed to waste method. Rockwool was previously soaked into tap water only for 24 hours. After first week I have measured pH of runoff and it was 6.6-6.7. Done heavy flushing with pH 5.5. Result was not much different pH - 6.5. More heavy flushing 4 days - pH 5.8. Two days after - pH again raised to 6.6. After second week i decided to use solution with lower pH 5.0-5.1. pH of runoff was 6.2-6.3. After third week I came back to solution with pH 5.5. Result was not good - pH of runoff was 6.5-6.6. Plants started to suffer, dry spot and dry areas have appeared. Everything about injured plants is described into thread: http://www.icmag.com/ic/showthread.php?t=109798
Today I made different approach. I pour solution into bucked (pH 5.5), dip every rockwool cube, one at a time, into bucket for about a minute. Time just enough to moisten the rockwool. After dipping of all plants, I have checked the pH. Result was interesting - 5.7. Does anybody know will this method help me?
Or, does anobody know how to stabilize rockwool pH?

Some pictures of injures (all pictures are posted into above mentioned thread):

 

[B. Self Reliant]

Some people will disagree with me on this, but I never base my decisions about Ph or PPM based on runoff.

I follow the directions that are on every GroDan Rockwool label in terms of preparation, and then I feed my plants with a solution of appropriate PPM @ a Ph of 5.8, with the last 2 weeks of flowering being a water & clearex flush with the Ph @ 5.5. In years of vegging in 3" & 4" cubes, cloning into 1.5" cubes and flowering in both hugo clocks and slabs, I've never had Ph-based problems, and therefor never felt the need to measure the Ph of my runoff. I also use RO or bottled water so I don't have to always worry if that's a problem.

For the record, I tried Rockwool in a ebb & flow system once and the reservoir's Ph was all over the place. It's just not the best medium for flood tables in my humble opinion, even if cleanup is easy after harvest! I've also had mom plants in Canna Coco Coir that were quite healthy. The runoff from that had a very high Ph, but I never made any decisions based on that information and those plants are still pumping out healthy clones to this day.

Hope that helps.

 

[Yes4Prop215]

Yea i am also having problems with my rockwool PH, my plants are showing signs of bad burning.

How do you effectively flush these things?? I have been watering them with a constant 5.7 and they are showing very bad PH damage.

 

[libby]

3 t1mes w1th rockwool, 3 fa1lures, must be someth1ng d1fferent somewhere.

 

[FrostyGreen]

I have problems stabilizing the pH of runoff from my hydroponic garden.

The plants are young (4 weeks old). For now I use feed to waste method. Rockwool was previously soaked into tap water only for 24 hours.

Hey lightmove sorry to hear about your troubles. In your post you never mentioned anything about soaking your rockwool in ph'd water. Rockwool needs to be soaked in 5.0-5.5 ph'd water for 24 hours. RW contains lime which causes ph to constantly rise if not soaked properly to remove it. Normally I flush RW with tap water initially and then soak in 5.5ph water for 24 hrs. Make sure to not have the ph below 5.0 as it will cause mushy spots in the RW(according to Grodan web site). On a run to waste you should normally get a runoff of +.5ph maximum from what your feeding them when flushing RW. Hope this helps and good luck.

 

[lightmove]

How do you effectively flush these things?? I have been watering them with a constant 5.7 and they are showing very bad PH damage.

I am flushing them with light nutrient solution (1/4 strength), pH 5.5. Using around 10 gallons water during 3-4 days, flushing from top twice daily, morning and evening. When first time made flushing pH was lowering every day with increment 0.1-0.2.
This was my first rockwool grow, after few days I will start using large rockwool slabs. Will soak them carefully and check pH before transplanting, until it stabilize. Hope that this will fix the problem.

 

[toohighmf]

to remove the lime, I find flushing them with clearex prior to conditioning at 5.0. Runs out the crap faster. Flush out the clearex with 5.5 water if ph exceeds 6 in 4 hours, revert back to 5.5 until 5.8-6.2 is constant. Once constant, add ferts to the rockwool w ph buffers like GH flora or other buffered nutes..

 

[lightmove]

Clearex sounds good, but I cannot find store in my country which sold this product. There aren't sold many hydroponics products, can be bought mostly nutrient solutions, pH Down/Up. May be I can find something similar into garden shops.

 

[toohighmf]

there must be either final phase, clearex, florakleen or something like it that you can buy locally or order.

 

[KifGärtner]

Water?

Water?

Are you using any type of distiller, or RO filter? i went through the same problem last year with my grow.

I flushed so many times I can't remember, replaced the res a couple times an nothing worked. My ph kept shooting way up after a day or so. The problem was I was using tap water and my ppm was way to high coming from the tap, just nasty water, so I got an RO/DI filter, and problem solved.

I realize RO filters are expensive in Europe but well worth it. I actually bought mine from the states on Ebay and still saved money even with shipping.

I hope this helps you out man.

edit: I also would consider changing mediums. All I had was problems with rockwool. I now go from my bubble cloner straight to expanded clay pellets. No problems as of yet, knock on wood.

 

[thecarguy]

What nutrients are you running? Get a good two part nutrient, like GH Floranova, DM Gold, AN Sensi or Connoisseur. These nutrients will be more pH buffered.

Next, get out of rockwool and let coco start helping you out!

 

[lightmove]

toohighmf there is final phase into my local grow shop. Thanks!

KifGärtner i use tap water, it is soft (65-75ppm). Filter are not so expensive (250 euro). But the things are getting worse, damages affected all plants, so I bought peat substrate, mixed it with perlite, and transplanted all plants into this soil. The damages are spreading very fast. Looks like I have done many things wrong.

thecarguy may be i will use coco in my next grow.

Thank you all for replays! I hope that someone else with similar problems will benefit from them.

 

[sponger2004]

Run-off PH

Run-off PH

Fuck

 

[Haps]

Yes, get rid of the rockwool, it is not friendly to mary. It is ship insulation.
H