Hi I am wondering about the google certified networks in my adsense account. I have heard many times that it only affects Image ads. Problem is I only run text ads but when I have it turned on my CTR plummets straight away if I block all the networks the CTR returns to normal. The thing is I only run text ads so why if the certified network is suppose to be image ads only does it affect my CTR so much? it surely must include text ads as well, because there is no other explanation for the CTR drop?