Help Advice Please

Hello
I just soaked my seeds for 24/30 hours only 3 thai shunk and two of these cracked revealing what i presume will eventually be the tap root........... which i placed 8mm below the surface of my 50mm rockool cubes and covered with a plastc bag to create a tent/dome effect, i then placed this tray with my three seeded rockwool cubes adequately soaked into my grow room under a 250w metal halide lighting system which im leaving on 24hrs a day until i have a seedling/sprout and the air temperature is varying from 26 to 29 C
"1st mistake" did'nt test my water ph or rockwool ph which turned out to be 8 so after 24hrs in this medium i remembered and flushed with the correct ph water and soluble nutrient mix (ph 5.5) leaving my three seeds hopefully undamaged so now today is day three for the seeds in the medium under 24hr light at a temperature of 27/28 C

any advice ??? is it too hot??? would the seeds be burned by an alkalinity of 8??? how long will it take for a cracked seed to emerge above the rock wool any thing else i should be doing ??? im using Canna nutrients Aqua vega a and b so i used 1.5 ml of each in 2litres of water and calibrated to an overall Ph of 5.5 to keep my seeds and medium moist

you shouldnt really be using nutes until they either start to show signs of deficiency or until the 4th or 5th set of leaves start...just ph'd water to start..poss a neutral mineral water that contains trace elements of minerals the plant can use..i use volvic.

the ph might have stopped them a lil...but if you flushed quick enough theyll prolly be ok.
they can take 3 or so days to start to peep out the medium..

dont use nutes untill 2 weeks after the seedlins break ground. the little guys will burn quickly. second turn off the light, they like darkness, humiddity, and warmth when sprouting.if any dont sprout, try lightly scraping them with sand paper. the method i use is i put a peice of sandpaper in a match box, then give it a few shakes. this wiil scuff the outer shell thus making it easier for water to soak into the seed. rockwool dries quickly, so make sure it stays hydrated. when you start feeding 2 weeks after they break ground, heavily dilute the nutes.... best of luck 2u

Hey what's up. Just a quick tip, i'd put that 250 away til they crack soil, just keep them moist but not soaking and in a warm dark place til they break surface, then maybe for the first week or so I'd just use some fluorescent lighting til they have their second/third set of true leaves then pull out the 250. Just my 2cents, have a good one! oh and I'd try to keep temps below 80F.

edit: And jay cas & frostythesnowthug are right on about the nutes, I'd wait til the cotyledons start to yellow(1-2wks), then you know they've used all their seedling food source and time for some nutes.