🙂
The chazon Ish is brought down in maaseh ish vol. 1, pg 132
see- http://www.hebrewbooks.org/pdfpager.aspx?req=51554&st=&pgnum=132&hilite=
if you are still looking into safek deroysa lchumra on safek techeiles I found a sefer on otzar hachachma called Mishmeres mitzvah (from a talmid of rav shimon shkop) that is very maarich to prove that we say safek deoraysa lchumra here. it can be seen for free on otzar hachachmah’s website since it is only 40 pages long