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Help with a deficiency


Well-Known Member
Hey all, working on my new grow, more info can be found here,https://www.420magazine.com/forums/...first-time-hydro-grower-looking-pointers.html but I am having some slight problems with 1 plant.
Lights - 400w MH, (was under a cfl for first 10-14 days)
Grow Medium - Rock wool cubes
Temps - 71 daytime, maybe 65 ish
Ph, trying to keep in 5.8 range but seems to drift
Nutes - 400ppm @.7 conversion

plants are just out of seedling state, they are in small pots, being watered once every day or 2, the ph of my run off the last time I checked was a little high at about 6.7. there is only 5 plants, and this one is showing a bit of a deficiency, I am thinking it is probably a ph problem, just looking for confirmation. I am using general hydro bloom, micro, and grow, along with calmag. Water temps are running in the 70 degree range or a little cooler. I have been adjusting the ph every time I water, but I think when I put my air stone into the mixed up solution that it is raising my ph. (it is drifting for some reason anyway). Any help would be appreciated..



Active Member
pH PROBLEMS - Rockwool has a high pH which means you have to adjust your nutrient solution low so that the root zone is neutral. Rockwool is also susceptible to pH shifts meaning more routine maintenance to keep the pH levels correct. Ii don't use rock wool in my setups for that reason, but that's my opinion. I like to take as many variables out of my set up as possible. Also look at advanced nutrients ph perfect line. It used it in my hydro and ph was not a problem for me.
Hope it helps.


Active Member
Sorry I should have asked too, did u pretreat you rock wool before using it?

1) Adjust the pH of water to 5.5. (NO LOWER).

2) If soaking A-Ok plugs, Macroplugs, or Miniblocks, mix in a little bit of plant food (no more than ¼ strength). Then just dip the starter in this pH 5.5 mix and it's ready for the seed or cutting.
3) For all other Grodan products- SOAK, FLUSH, and then PLANT! Soak in plain water (pH 5.5) for 1/2 an hour (longer if soaking granulate).
4) Flush through with pH 5.5 water mixed with some plant food. Make sure the flushed water goes to waste, then plant into your prepared Grodan block, slab, growcubesâ„¢, or granulate!

DO NOT SQUEEZE the cubes or blocks. They are designed for the perfect air/water ratio. When you squeeze the product you may ruin the good structure.*


Well-Known Member
I started them in cubes, and now the cubes are transplanted into pots full of croutons of rock wool.. Pre treated rock wool to 5.8 with no plant food, straight RO water. watering with plant food at about half strength for last 3 days, ph seems to drift though. I have adjusted ph a number of times in my mixed up plant food container. I adjusted it yesterday, and today its back up to about 7.0, would my air stone be effecting the ph at all?? Or is it because I am using apple cider vinegar for ph adjustment?? I have some ph down coming in the mail, but trying to make due.


Active Member
Yes give it a go. I also tried back in the day to use other options. Just to unpredictable, so I got the good stuff and no ph problems anymore :)


Well-Known Member
I found the best way to hand water rockwool, is with ph 5.8-6.0 a few times a day. Just water with a little bit each time. Water with food, then later that day water with a little water.

Just don't water to much or you will keep the rockwool soaked. However, if you just water with just enough water to cover the top area of the rockwool, like a few ounces, then the rockwool will have time to dry out and be watered again the same day.

indica vet

Well-Known Member
slow down on the watering its only a small plant ,overwatering is the biggest cause of issues with young plants,especially using rock wool.
let them dry out a little. less is best to begin with.
the leaves yellow when over watered because the fine hairs around roots die, which halts nutrient uptake.
may also be related to changing from cfl to hid lamp ,keep the hid lamp further away than standard height adjustment until they get used to the strenghth of the lamp.
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