PH value of rockwool and water?

[Sith]

Hello,

I'm currently growing some seedlings in rockwool. I bought a rockwool tray from a growers' store, and at first the seemed to be ok. I read it was recommended to use distilled water until the first parts of the plants showed. Then I just used plain tap water.

The first week I used a MH lamp, but changed it to a low energy lamp. Within two days half of them died away mysteriously, at first I suspected overwatering, its hard with these rockwool trays to reach each plant to water them separately, then I also suspected it might be because I didn't have the correct PH value in the water.
I then changed it using a PH- fluid, and it seems they stabilized.
But now I've noticed some beige spots on some of the plants, on the leaves, not mainly the tips, I don't think my lamp is too close to the plants, so I'm beginning to wonder what can be the problem..
I used some mild fertilizer one time, I wonder if this might be the problem, the spots came about two days later..

I just transplanted the seedlings, they are just 11 days old, to net pots, and added some extra rockwool,
I measured the PH value on the rockwool cubes from the hydroponics store with rockwool used for isolation purposes, I thought this should be equally good to use, I added some unmodified tap water to the different rockwools and found that the building rockwool's PH value was slightly higher than that of the rockwool cubes.

I was reaching for a PH value in the watering water of around 6, but when I soaked the rockwool with it I discovered that both the rockwools got a higher PH value.
I wonder if this is a problem, and whatever else the discolorings on the plants may come from. I bought "The cannabis grow bible" by Greg Green, and I couldn't match this to problems and diseases he listed..

I'm sorry for the rather lenghty post, I'm totally new to hydroponics, I'm just using it to maximize my harvest, and English isn't my native language either, and on the top of that, I'm a bit drunk (I live in Europe, so I'm a few hours ahead..) I will definitely add some experience of my own later on!
I'm thankful for any informed input on this!

I realize I might've got the answers by searching this forum, but the questions are rather specific, and I don't have the time to spend many hours looking for answers, either I just try and fail on my own, or maybe some of you are willing to add some valuable input which will reduce my labour, and also maybe not more plants will die away from me..
I could have used clay pellets instead, but none are as big as the holes in the net pots..

 

[trichomes]

need pics, this should help

 

[Sith]

Thank's for the answer trichomes, but I don't think overfertilizing is the problem, I've read the you don't need fertilizer until about three weeks after you've germinate the seeds, and the leaves don't look like any of the pictures. I'll have another look at the plants tomorrow, and also look at my technical possibilities of uploading a picture, safe and anonymously.

 

[toasted]

Hey Sith,

Its sort of difficult to tell whats going on as there's not enough information to really nail things down. If I may, I suggest you take a picture or two, strip any geo-coding (just to be safe), and upload here and then post (you can even upload & use the site via Tor if you really want to be anonymous).

What sort of setup are you running? I see you talk about netpots & rockwool... you are doing Hydro right? If so i'm assuming DWC setup? Perhaps something else?

This then leads to how/when are you changing the water? If doing hydro, how will you be aerating?

At 11 days you should just, and i mean just be starting to do like 1/4 or 1/8th strength fertilizer (ideally a type made for hydroponics If thats what you are doing), but again depending on if you are doing any sort of soil or 100% hydro the details will be a little diff.

It's also hard to tell from your post how exactly you are adjusting the water - are you applying pH up/down directly to the try where your rockwool is? Or mixing it elsewhere and then adding? Note you should *never* apply the pH up/down additives directly to *any* tray/reservoir/bucket/tote/etc with live plants in it. That can lead to bad things, especially if some of the concentrated goodies make it to any part of the plant.

See what you can do about getting a pic or two and then we can go from there

Best of luck my friend!

 

[Sith]

I tried to upload pics but it seems I don't have that possibility.. Have sent PM to an administrator, hope the plants survive until I can upload pics..