what you might have is a ph fluctuation associated with the rockwool,at two weeks old those plants should be able to handle a full strength application of nutes providing that the ph is adjusted to 5.5-5.8 after you added the nutrients.using urine is a very bad idea,especially in hydro,all that does is contaminate the reservoir and the nutes in it,good quality hydro ferts are used by the plant instantly and they should contain all the secondary and trace elements as well as the major needed by the plant,with rockwool you must check the ph every day and adjust when necsesary,and it has to be stabilzed before you grow in it with a ph down solution of 4.5 for 24HRs,also keep the reservoir temp at around 65-68fh....bonbon
http://www.highlife.com.au/man/growing.htm
bonbon Reviewed by bonbon on . Day 15 in the big bud'er house..all well until this... :confused: Day 15 today and all was looking well at first glance. However on closer inspection many of the plants seem to have a faint yellowing around the edges of the leaves; And one or two of them have what seems to be some nutrient burn on the leaves- not too many thankfully. see pics below. The reservoir had around 15 litres of water in with the nutrient strength around half of what was recommended. I topped the tank up with a further 30 litres of ph balanced water and also gave the Rating: 5