Hey frogster, no problem buddy just don't hijack my thread by posting pics in it as that can make grow journal threads confusing. A couple thoughts on your sitch. The ideal humidity for veg is typically in the 70's with some research saying that it should be in the 80's it your temps get into the higher 80's. Clones and rooted clones generally do better in a higher humidity as transpiration increases with increases in the difference bewteen the water content in the leaf and the water content of the air. Please see my thread about the three major plants proceses that was pretty much ignored in the beginner forum
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https://www.rollitup.org/newbie-central/388616-little-plant-primer-newbs.html). Transpiration is simply the absorbtion and movement of water through the plant and for a large part, is a function of temp and humidty). If your new plants are forced to absorb and evaporate large amounts of water that they do not have the ability to uptake due to immature roots, this could cause problems.
This is the explanation behind my suggestion to raise the humidty to 60-70 if you can.
On to the feeding and flooding. I'm not a fan of rockwool for the very reason that it is overly absortive. That and handling dry rockwool puts tiny inhale-able shards if glass in the air. Letting your plant medium dry out a little can have a positive effect of stimulating root growth. However, younger plants have less of an ability to survive moisture stress. So with freshly rooted clones it's a very fine line. I would start to flood them now, if you have precise control of your flood level, try to stop the level of the flood right below the rockwool. The roots will grow down into the hydroton and you will be fine.
If your worried about too much moisture and root rot, I would highly suggest the addition to some hydroton peroxide to your rez. A gollon of 32 or 35% solution is like $12 and will last a long time. The hydroper will increase oxygen levels that will prevent the multiplication of bad fungus and bacteria which is the actual cause of root rot. I always run a week of h2o3 whenever I transfer plants to a new growing medium to somewhat steralize them. I also add a dash if superthrive which is very inexpensive and an excellent source of b1 and thamine which jump starts roots. It WORKS as the above picture of my bubble bucket clone roots can attest.
And last but most certainly not least, your nutrient concentration. I'm using organic nutes which apprantly, can be difficult to measure ppm accurately. I followed someone elses nutrient schedule and had around 240-330 ppm during the first week. My plants suffered all kinds of problems and i freaked out (mind you I also had hydroton ph problems which likely excerbated the problem). Of course I got a myriad if generally unhelpfull advice from the forum but I showed a picture tinny hydro store manager he needed about 2 seconds to say "your underfeeding them". I took ppms to around 500 and they bounced right back. My suggestion therefore would be to go ahead and run the 300 for 4-5 days and let them settle in a bit but I would up the ppm to around 500-600 by day 7. The salinity of your roots should slowly increase as the plants age but even at this stage, a ppm of 500 would not be higher than the roots which would cause the cessation (or reverse) of nutrient uptake do to the lack of saline concentration in the root zone (again see my thread for explanation).
Hope this helps.