Oh, Rhizotonic is supposed to be good for root health and growth so I use it to prep everything with nothing to do with the SIP.
Azimuth, as per cardboard and does it need replacing due to rain, no it does not. I place new cardboard Just once a year, when planters are deployed in spring. Rain doesn't hurt them. We don't get a great deal of it in the growing season here - we get more than our fair share in winter -...
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This thread probably has the most info on it and there's many ways you can easily make one.
The roots at the entrance didn't eventually really form a problem, one would preferably want roots everywhere, it's just that my pot is kinda a bit too big for the size of grows I do in the tent. I keep the plant very compact and yes the buds were definitely an enjoyable size, if I had a bit more power in the light I could get them a lot longer as well but the girth was surely thanks to the SIP as she can drink and eat whenever she likes.
I think I could avoid the roots at the entrance if I first form a root ball and uppot..then I'll probably have roots that do a lot more soil exploring before hitting the lower layer but because I seed into the pot that first root goes straight down until she reaches the goodies.
And you're right shaping the plant with mainlining also does a lot to improve the buds you're getting. Structure is key certainly inside under LED you want everything to be the same size & height.
I would definitely try one out if I were you, the ease of just being able to fill a reservoir and not worry about when to water is a huge thing, being able to feed full strength nutes all the time is also big.. I'm on my second SIP grow now and it's also looking good, I have yet to see a complaint of the plant.
My theory is that because you're not pouring everything through the root system but just let the roots do their job pulling things up she can be a lot more selective in using and steering what she needs.