From what you are saying, I'm guessing you are not far off from doing everything correctly. However, you are guessing as well. Your water schedule is a bit more than necessary. I have a similar systems and I water every 4 hrs. But 3 hrs are ok, as long as you are using hydroton or clay pellets. You might want to be careful about not putting the little starters in there if/when the roots are not or barely coming out of the rockwool cubes. They hold a lot of water, and are not meant to be watered that often. I have found that removing as much of the rockwool as possible so the roots are get lots of air really helps, once they are boying that stage it's not that important.
You need to get yourself an e/c or PPM meter so that you know where you are with the nutrients. It's a $25 investment that will more than paying for itself. Once you mix the nutes with the water, you will be able see how strong the solution is. You have to know where you are in that matter. Check them out on E-bay.

keylime

Quote Originally Posted by Jbomb83
yo. I am currently two weeks into growing some feminised white russian.

using a 1.2x1.2x2m grow tent

venting hot air out from inside is a 6" carbon filter connected to 400w hps lamp inside a 6" cool tube to 6" inline extractor fan with an extraction rate of 650 m3/h. cool air inflow provided at the bottom from a 4" inline fan outside the tent from a window. the top corner inside tent has a large desk fan diagonally angled down and inward, with another desk fan at floor level.

using a flood and drain system with four 10 litre pots, growing medium is clay pebbles, using rockwool to root the plants in, with 1 plant per pot. reservoir is currently holding 40 litres of water with a ph fluxing from 5.2-6.0 as the day progresses. flooding every three hours. just added nutrients a few days ago - im using canna hydro a+b at 1/4 of the strength recommended.

the temperature inside is a steady 26c never rising or falling more than a degree or two with an average humidity of around 45%.

so far everything is going well and the plants are looking rather healthy. vibrant green, nice fat stalks, very close node spacing. however some of the fan leaves are curling up and some curling down.

im pretty sure its not the temp, cool tube sorts that out and using hand test the radiant heat is very low at their level. im thinking the introduction of nutes few days ago was too much and shocked them even at 1/4 strength. since then ive added another 10 litres of ph'd water so its diluted further. also they've doubled in size in the last few days so must be eating nutes up too. current growth rate is looking very healthy. they certainly arent being stunted from it.

my questions are- do you think i over fed them?
- other possible causes?
- do you think the diluting and plant eating will have been enough to prevent needing to completely change reservoir?

im sort of feeling i should ride it out - i reckon they'll kind of smash past the initial shock and everything will begin levelling out. soon being at the point where i cant feed and water them quick enough!

thoughts?