New to grodan (rockwool) and switching a light to test

Discussion in 'Hydroponics / Aeroponics' started by Slimjimham, Nov 29, 2016.


    Slimjimham Well-Known Member

    Ok guys, if you're on instagram you've probably seen the jungle boys, and we all gotta admit they're killing it. So I figured if they're using this style, many large veggie green houses using this style... There's gotta be something to it

    So I'm going to run drip to recitculate in 6" cubes, I have the floraflex caps, a titan 2 timer for watering during lights on.

    I'm going to be running a 6' x 4' table (only thing I haven't purchased) with a hole cut in the bottom. I'll have a rubbermaid container under that pumping water in a hose to the plants driplines. I'm going to try running 12 plants in this space under a light (4 rows of 3)

    Ill be using canna substra A&B (soft water)

    With a calmag (MagiCal by techniflora or CaliMagic by General hydroponics, haven't decided)

    I think I'm going to stick with just that for the first run to see how it turns out.

    I have clones going in my aeroponic cloner ill be putting in these...
    (^clone cubes)

    Clones should be ready soon and I'll start posting pics...

    Anyone who's experienced please jump in to help me through!!!!!

    Im going to run it somewhat low budget as far as table stands (gonna use cinderblocks) since I'm just trying it out.

    Anyone grow this way??? Jump in!
    Carolina Dream'n

    Carolina Dream'n Well-Known Member

    The secret to rock wool is getting the soak right.

    Make your soak water 6-12 hours in advance. Ph it right when you make it, come back again later and ph it again (it will most likely raise back up after initial ph down dose). Make sure the ph is stable at 5.5-5.6. Now add your cubes, the ph will raise a few points to around 5.7-5.8. Soak big cubes at least 12 hours.

    Roots excelurator has great results when used on your initial soak of BIG cubes. Do not use on cubes for taking cuttings.
    ThegrowerMOJO likes this.
    Carolina Dream'n

    Carolina Dream'n Well-Known Member

    The style in which they grow is VPD (vapor pressure deficit). You increase temperature and humidity to allowed the plants to have more gas exchange therefor leading to faster healthier growth.

    Then slowly taper the humidity and temperature down during flower to get back to a "normal" environment for the last few weeks.

    Slimjimham Well-Known Member

    No doubt, and right now I grow one perpetual room so I can't do that, humidity is always 46-50 in my room. I'm talking about their rockwool drip style...

    Anyone grow in grodan (rockwool) with tips? Just ordered the table today... Something like $94 before tax for a 4' x 6' tray... And that's cheep around here! I should be in the table game ha, you know those cost the company less than a few bucks to make ha... Probably pennies!

    budman111 Well-Known Member

    The general consensus here is that it is mediocre since the removal of a certain growth hormone a few years back.
    Carolina Dream'n

    Carolina Dream'n Well-Known Member

    Just finished a side by side with it. While I can not say anything on the old formula, the new one (silver bottle) outperformed the plants that did not get it. I'm using 50-100ml of it max per harvest. The cost are so minimal compared to the results.

    waterproof808 Well-Known Member

    Google "Coco Trees" and read what Don Juan Matus has to say. Its not about rock wool specific but a lot of his knowledge can be applied to rock wool and other mediums. Lots of good info in the thread.
    Blue brother

    Blue brother Well-Known Member

    WP_20161203_20_33_10_Pro (2).jpg this is exactly how I grow however I use these

    here is a link you'll find useful, it's about grodan vital slabs but I've done both and although they're a tad different ive found they behave pretty similar irrigaton wise.

    take note of crop steering, read up.

    I don't like dripcaps they restrict air moving into the top of the block.

    I usually go 1inch cube from clone to 4inch cube then sit on top of 6inch cube

    I water a large volume every time I'm talking like 200% run off, this keeps the rootzone as equal as possible allowing you to read and treat the res as if it were the rootzone.

    soaking the blocks is pretty straightforward. Hold them under warm water for a minute or so then fill a bath with water ph5.5, water a few litres of thatbthrough them with the block standing in the sink, allow it to drain to waste then throw the block in the bath for an hour

    I like canna notes however I would suggest using aqua, it's more stable when recirculated than substra. I use aqua and pk13/14 and bleach, that's it. It's enough for my strain.

    plenty air in the res cos although it's very hard to over water you can under oxygenate when you're feeding from the top frequently in veg

    if you wanna know anything specific let me know
    Last edited: Dec 3, 2016

    Slimjimham Well-Known Member

    I'll deff be looking for specific soon. Hit me with any tips you learned along the way you wish you knew sooner. Thanks guys. Clones should be going in, in the next couple of days

    JDMase Well-Known Member

    Hey man, I use rock wool, I have a thread called "growing with rock wool as a substrate"

    I use the plugs for seeds, once they are root bound into 3 inch cubes, then I put those into a plant pot full of the small cubes and top feed like you would coco or soil.

    I only soaked them for like 15 minutes to begin with, ph at 5.5, then I follow what one of the guys on that thread said of tapering the ph up throughout the grow, I do want to run automation (put a thread up earlier but no responses as yet) so hopefully we can learn from one another!

    Good luck with your grow. Happy to answer any questions you have if I can.
    Blue brother

    Blue brother Well-Known Member

    letting rockwool dry out completely totally ruins the great wicking and water holding properties of the substrate, aim for a wet-moist cycle (rather than a wet-dry cycle) until you find your feet, what size plants are you planning on growing? How much veg?

    Slimjimham Well-Known Member

    So I'm gonna start by saying I'm pumped with all the input and interest so far! There will be lots of posts when its starting (tomorrow)

    I'm currently running current culture 4 sites under each light growing trees... So this will be a change.

    I'm planning on growing many small plants under each light, im starting with 12 plants in the grodan hugos under one light

    Because of schedule these plants will only have 3weeks 4days of veg (25 days)

    But think that will be good since I don't want them getting more than 3' ish considering my normal ceiling height and the fact they need to be on raised tables.

    It's all an experiment for me.

    What veg ppm should I feed the clones I'm putting in 6"x6" hugos?

    I'm used to growing real low ppm with hydro (under 450 on the 500 scale)

    Thinking about starting out with 300ppm on 500 scale in veg, bringing it up to maybe 500ppm at the end of veg... Raising it to around 700ppm (1.4ec) in peak flowering... Does this sound about right?

    Also with 30ppm tap water (I have ro but trying not to use it for this because it's a waste of water...) how much calmag should I be using (in ppm)

    I'm also used to growing STERIL, should I be doing that with grodan or like said am I better off using greatwhite (myco) and roots excelurator?

    I'm also planning on keeping the flower 'nutrient res' chilled to 65* this a good idea or unnecessary?... I find its very important with my rdwc systems


    JDMase Well-Known Member

    Hey man, have you checked out some videos on YouTube? Everest f has some awesome videos.

    Neil from grow pot cheaply (YouTube) has a hour log tutorial too. (Can't rmemeber the name of the video but you'll see him outside on his decking with some buckets) that was where i got to grips with it.

    In regards to Ppm I think the most optimal way is to raise the ppm to the point you JUST start to get some tip burn, then back off. (Got that from neil)

    Everest does a video on osmotic stress and says you should never flush with pure water (but you probably know that already)

    With my autos I had to wait until they were at 4 nodes before I could touch them with nutrients, I gave them about 300ppm with their first feed. If that helps

    Slimjimham Well-Known Member

    Have any pictures of your plants in flower?

    Also prob my biggest question what is everyone using as a ppm base of calmag? (500 scale)

    I have 0 ppm water, rethinking things I'm going to stick with the RO water.


    JDMase Well-Known Member

    This was the 17 November image.jpg

    JDMase Well-Known Member

    This is today. Sorry for shitty HPS quality but you get the idea.
    Blue brother

    Blue brother Well-Known Member


    here's some food for thought Il answer some questions when I'm less busy tonight
    JDMase likes this.

    JDMase Well-Known Member

    I think I'm gonna switch to those big girls, do u have to run the roots in a ebb and flow or drain to waste and water constantly? Or do u just water them on a timer and let the cube stay wet.
    Blue brother

    Blue brother Well-Known Member

    water is pumped from a reservoir periodicaly through a hose and manifolds that feed each plant from the top, the run off drips from the bottom of the cube into the tray which is on an angle, then out the fittings at the bottom of the tray into a piece of guttering which runs back to the reservoir. True recirculating hydroponics, this system can be seen on a massive scale allover Holland in their hydroponic greenhouses. The trays work brilliant with both the 6" Hugo blocks and the 1m grodan slabs.
    JDMase likes this.
    Blue brother

    Blue brother Well-Known Member

    you know ur strain. Feed the same strength solution that you do in any other hydroponic system.

    I tend to feed A LOT less than other growers, I don't believe that you should increase til the plant burns then back off. There's an optimum band of ppm that your plants respond best to, in my experience that has never been just below the point where you see burned tips.

    my plants behave best at a max of 1.4ec. If I wanted to I could push that up to 2.0ec and still see no burned tips, but the plant wouldn't be as happy as it is at 1.4

    I run sterile in rockwool, sodium hypochlorite and ozone keep my res and rootzone sterile. I have had good results with alot of different live additives but sterile is alot more foolproof so that is what I went back to.

    I use an aquarium heater set to 20'c. My problem is never too much heat in my res, it's nearly always too cold. You will find your res runs alot cooler than in rdwc so you may not need to do anything, I find 20'c to be the happy medium between dissolved oxygen content and nutrient efficiency.

    hope this helps
    666888 and JDMase like this.

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