If you're having trouble getting fluid off without drop in BP an cramping, there are a few options.
The first is obviously to see if you need to raise your dry weight a little bit.
Sometimes though, people crash without hitting their dry weight. There a few really simple things you can do to help fight this.
Have the techs lower the temp that your blood is returning at. The warm fluid that is coming in from the machine is a vasodilator, meaning it makes your entire vascular structure expand. This results in a lower blood pressure. Cooling this just a tad helps to constrict your vessels a bit, reducing the risk of that BP crash we all hate.
Another option is to make sure that UF profiling is enabled on your machine during your treatment. This alters the UF rate throughout the treatment, so that you're pulling more off at the beginning, and less off at the end. There are a number of different UF profiles, but the most "even" that I've found is #2 (on the Fresenius 2008H and K models).
Sodium profiling is also an option if you're cramping a lot.
I personally prefer my own version of sodium profiling: I make sure to bring a nice meal with me, and I try to load it up with some of what's being depleted during treatment. I then eat it first thing, as eating it later may further compound the problem of low bp (all that blood rushing to the stomach for digestion).
I find that this helps to replace a bit of what's coming out. Also, if you bring a drink with you, factor it into your goal so that you're not wondering why you're overweight when you leave.
ALSO: keep in mind that the food you just ate has mass and therefore has weight - but shouldn't be factored into your goal. If you seem a little "heavy" when leaving, and ate a foot long sandwich, don't worry - as that food digests and leaves, so will the weight from it. Unfortunately many techs can't understand this very simple concept. (first grade science anyone?)
Bring in some pickle juice, or chicken broth, or something salty that you can drink a bit of if you're beginning to feel woozy.
You can also simply ask the tech to turn off your UF for a bit, because you're feeling kind of dry. This means that the machine is continuing to dialyze, but is not pulling off any fluid. You want to (if at all possible) get your full treatment in.
More dialysis always = good
Your peers are getting kidney function 170 hours a week - you're getting 12.
It can be very hard to finally find a weight that feels "right" - and a system of avoiding those nasty bp crashes. This place is a great resource though, as we can all share what has worked for us, and in doing so provide a veritable encyclopedia for the newcomer.
Good luck spinner!