you don't want to kill your estrogen completely.
umm...IMO, as long as you're not getting high estrogen related side effects like gyno, if you're taking in testoserone or what you're taking is converting to a form of testoserone, your body will compensate and bring your estrogen up. that's when you get water retention. this can be a good thing. makes you look bigger and makes you stronger and lubricates your joints but some people don't like the bloated look and it can be bad too. lower back pumps USUALLY occur due to extra water retention. also, being bloated tends to cause blood pressure to rise.
as i always say, just let the compound do it's work.
but if your serioiusly worried about it and don't like it, you can take something like adex on cycle for your estrogen levels and it should not effect your gains.
having high estrogen POST cycle is where you have to worry though because your estogen will be higher than your testoserone. your testoser post cycle will be shut down. your goal post cycle is to get your natural test levels to shoot back up as fast as possible while controling and lowering estrogen levels.
i'm not one to get too scientific about this and i am used to the old way of doing things but this is why i use both clomid and nolvadex post cycle.
clomid 50/50/50/50
nolvadex 40/40/20/20
that usually gets my nuts back to normal as well as the libido (clomid)
and the nolvadex helps me not to get gyno and also helps lower estrogen.