You could have ovulated yesterday and still had enough of the hormone in your system this morning but not by afternoon. My surge was short which is why I tested twice a day - normally the darkest line was in the afternoon.

you're not supposed to use first morning urine for OPK. Afternoon is best.

I tried the cheap ones and get two lines for like six days in a row using first morning urine (the package said to). I always got one line later in the day. I concluded that for me, whatever chemical reaction they were tracking was not registering in a useful way and switched to a digital OPK. Sorry.

I am new to using the strips. I'm using the cheapo ones where two lines is positive, one is negative. I tested first thing this morning and got two lines for the first time. However, I've tested twice since then and got one line. I know that one possibility is that my surge is short, and that the positive is real. However, we went out last night to a Mexican restaurant, where I had several margaritas, tons of salty food, and not much water, so I was pretty dehydrated. I'm just wondering if the two lines could be the result of my urine being "different" this morning because of alcohol and dehydration, as opposed to hormones.

Any thoughts?