Rockwool and PH i just can't get it to saty steady???????? WHY WHY WHY

Can anyone lewnd some insight, I cant be the only one with this problem. I PH my rockwool like it shows in the video to 5.5, but still my PH is on a steady climb to the top??? I us plastic containes for pots, baskets and rez, pumps sealed plastic, lines are all plastic. Air stones maybe, or is it the rockwool, that what I think. Can anyone give me some tips on how they cure/treat the rockwool to get the PH to stay steady?

P.S I have tried, just for an experement to see if its the nutes by just running plain water and back to the 7's it goes, hey what if the PH DOWN is somehow degrading in the water any one ever heard of that, its store bought crap??
Thanks

I have heard that Rockwool can have an unsteady PH so it may just be the Rockwool. I have only heard this, and not experienced it, so don't go on my stupid comment alone. I am sure someone that knows Rockwool will chime in.

Good luck and keep it green.

Idk what video youre talking about, so how long did you soak and the water was 5.5 when you put the rw into it?? What was it when you took them out?

What worked for me was to soak them in 5.0 water until the water rose to about 6.0, then put them back into new 5.0 water. I do this until the water only rises to 5.5-5.7. I know people have the 12/24/36 hour recommendation, but since you're ultimately trying to level out the ph swing, why not do it until the ph is fixed instead of following a clock that could give a shit less. Not that you did, thats just my take on the common prescription.

What ph down do you use? I've used phosphoric acid(most store-bought ph products use this) and sulfuric acid(yes, battery acid) for down, potassium hydroxide(again, most storebought products) and sodium hydroxide(lye) for up. I dont know how that could degrade water, or what degraded water is for that matter lol. Do you filter your water? If not, do you have a water analysis from your water provider?

Try and soak them in ph'd water for at least half an hour. I just rinse and then put them in a bowl of water. Then use Gh's ph down to 5.5 and go do shit. Works for me..

For my 6x6 rockwool blocks I soaked them in ph 5.5 water for about an hour, then held each block until the water stopped pouring out of it, then after putting it on the flood tray i rinsed each block with a mild nutrient solution which was at ph 5.8. After transplanting for the next week almost the runoff each block was near ph 7, which worried me however throughout the week i hand fed them from the top with nutrient solution of ph 5.8 and once they established roots in the big block the ph dropped to 5.8-5.9 and it stayed that way.

Tap water is ph 8 around here. So check that first if you are watering them with non ph'd tap water then it will go up.

I use rockwool no issues. You soak the cubes overnight in ph 5 water. Then the next day take them out and fling dry the excess water out of them do not squeeze. Then you add your plants, clones or seeds. Once they are rooted through the cube you begin feeding them. Make sure your feeding solution is about half strength till roots hang and keep the water in the res at 5.5 ph and keep its temps around 68 degrees. Then make sure the grow area is about 70 F to start until well rooting starts. Higher temps raise evap and ph will rise. You must soak the cubes over night in the ph5 water or you leave the ph to high as they dry. The ph 5.5 res water helps keep it down until roots can use water and food in the correct ration. What nutes are you running?

Its normal, Rockwool will never stay steady. I check it and fix it every day before I flood my table (once a day) thats just the way it is! some peple will say you can get it right...but thats just not true!.. its a bit of work to do that every day, but I say...if your not with your plants every day for atleast an hour you probabley wont get good results. this is a picture of my plaView attachment 2159879nts right now on day 12 of 12/12

I've never gotten a good answer for the phenomenon. Small blocks always have a ph stability problem. Once I put plants onto slabs the ph stays pretty level, but they're also getting watered periodically by a drip system rather than by hand. I thought it might be a result of the moisture level dropping in the small blocks causing salt build up. Grodan claims that the medium is ph neutral and will stay stable once you rinse them sufficiently but that has not been my experience.

Hmmm surprised you guys have issues. used it for over 15 years and never have an issue unless its not ph 5 soaked over night.. It is ph neutral as grodan say at 7 but you want it at 5.5 little acidic as MJ likes

Also 3x a day feeding is way OVERKILL......Rockwool hold so much water, start with once a day and feed an hour after the lights go on....go check on them 1 hour before the lights go off and see if they are drooping. If so then feed 2x's a day at equal times during lights on. My guess is they will not be drooping on a once a day feeding. Sooo many people over feed hydro in Rockwool and when you do that you are asking for problems...less is always more in rockwool!..look at my plants in the picture i just posted. They have never been fed more then once a day. Look how perfect the plants are. No leaf burn no def, they are magazine worthy...thats what you want them to look like!

FilthyFletch said:

Hmmm surprised you guys have issues. used it for over 15 years and never have an issue unless its not ph 5 soaked over night.. It is ph neutral as grodan say at 7 but you want it at 5.5 little acidic as MJ likes

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whats up fletch???? I read a book a while back and it said the reason PH in Rockwool is always off is because the plants take in and excreet so it throws the ph off every feeding! what are your thoughts on that?

I just realized that last post sounded real cocky...it was not my intention at all. Just trying to help!

Cheap airstones WILL cause the pH to rise. I have a feeling this is your problem. I used to have a rez that I would adjust to 6.0 pH and every time without fail, less than 24 hours later, my pH would be close to 8. I replaced the cheap airstones with some decent air diffuser hose and problem solved.

silusbotwin said:

Cheap airstones WILL cause the pH to rise. I have a feeling this is your problem. I used to have a rez that I would adjust to 6.0 pH and every time without fail, less than 24 hours later, my pH would be close to 8. I replaced the cheap airstones with some decent air diffuser hose and problem solved.

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Interesting! air stones are have no PH and air shouldnt change PH...interesting none the less

Uptake and intake will change the ph of rockwool and any substrate. The more water used means 2 things either evaporation or plants are drinking more. This means less nutrient uptake and more cast off raising the nutrient sals and ph. This is why its always a good idea to run a clearin soluting for a day between new res changes. It pulls the salts out helping you control the ph. The bigger the plants get the less the rockwool ph and res ph will flux.I have never gotten a flux higher then like 6.2 from the 5.5 and that was a tent that got real hot with couple 1000 watt lights so the plants were drinking more then eating.

FilthyFletch said:

Uptake and intake will change the ph of rockwool and any substrate. The more water used means 2 things either evaporation or plants are drinking more. This means less nutrient uptake and more cast off raising the nutrient sals and ph. This is why its always a good idea to run a clearin soluting for a day between new res changes. It pulls the salts out helping you control the ph. The bigger the plants get the less the rockwool ph and res ph will flux.I have never gotten a flux higher then like 6.2 from the 5.5 and that was a tent that got real hot with couple 1000 watt lights so the plants were drinking more then eating.

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Always with the good answers....you da man!

marc88101 said:

Interesting! air stones are have no PH and air shouldnt change PH...interesting none the less

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Blowing oxygen in your tanks after adjusting down makes pH rise...big time.