congrats on the status fishcake,
i have poked and pushed seeds down in the water in the past and find some sink after a bit of a push, now i have used the sandpaper method but i dont stick them in a box and shake it up, i get a sharp knife and run it around the edge of the seed gently scraping a tiny bit away, doing this seems to work with difficult seeds, ill give this method a try with the kiwi seeds, when i got the seeds out of the buds i collected them all up and picked them up 1 at a time and gave them a squeeze, several was empty and was just a shell, so not sure what happened their, then i kept the solid seeds, but the ones that cracked was just a seed shell, but the solid seeds i kept and get a few hundred of, so i got plenty to germ and if i only get 3 out of 10 then its cost me nothing, i did not buy the seeds so if they dont sprout then they dont sprout,
@spring, as soon as you give the soil a try you will have no problems getting it all dialed in, i think once you have done the first round with soil then you will have some idea of how much water they need and stuff like that, before the roots grow out the bottom i use a spray bottle and just give it a few sprays around the seedling, this seems to water it enough without being to much, the problem is the medium is so small that it gets drowned quick but it also dries out very quick, so until the roots poke out the bottom and into the res its just a case of giving it a couple of sprays twice a day or more depending on temp.
but id start them in the little seed tray type things, then keep them in that till they have grown their 1st set of true leaves, then transplant into the top of the dwc, i pull the soil towards the edges so when i put the seedling in it sort of fits into the hole you just made, then below this is about an inch to an inch and half of soil, then within a couple of days you will see the tap root sticking out the bottom where the lid of the bottles used to be, so this is when i fill the res and turn the air pump on, then i make sure the level of the res is below the level of the top part, so it leaves a gap of air between the top part and the level of the liquid, doing this will stop the top part getting drowned, then the root will be getting splashed by the bubbles and this will make it grow like crazy and once its in the res the growth of the roots is shocking,
i know you wont have any problems with the soil, its just a case of getting the watering right for the first week, then after that the roots drink all the want from the res, i then just water a bit through the top every 3 or 4 days to stop it totally drying out, doing these seems to be the best method. it works and works well, but once you get the hang of how much water to give at the start then you wont have any further problems, by starting the seeds off in a seed tray your giving them the chance to be a bit stronger before they go into the dwc, then its less likely to have the problems like you had,
give me a shout if your unsure of anything, but by looking at what you got it looks like you got it all set up right, it was just the growing medium thats causing the problems, if i had used that medium then i could of helped, but ive never used it yet so cant comment on how often to water and stuff like that.
now once the roots hit the liquid in the res you need to make sure the nute mix is not to hot for the plant, now i use bpn and i go about 3/4 strength of what it says for the 1st week or 1st res change, then after that the plant can pretty much take the strength given in the feed guide, ive not had issues with nute burn in any of the dwc's yet, but i have not pushed the plants to much either