I have had readings of 1018 since thursday. i gave it a little shake on friday like suggested but it still hasnt changed. it stuck at 1018. being a stupid noob, i didnt think about it being too high, and added finings yesterday. is it ruined? could i try addidn more yeast?
If it
still at 1018 after rousing the yeast on friday, don't worry too much about it. Give it time for the finings to drop the yeast, and then bottle. 1018 sounds high still, but if it won't drop, it won't drop. Theres only so much that can be done.
When you bottle, make sure you don't over prime. Give one bottle about 5 days, then chill it down, and open it up. Carbonation normally takes about 2 weeks, so if after only 5 days its overcarbonated, it means that it was bottled too early. If that happens, slowly release the pressure on the other bottles to vent out the gas, reseal them after a couple of minutes, and do it again a couple of days later. On the plus side, grolsche bottles are easy to do this with.
If after the first 5 days that sample is still flat, or is only lightly carbonated, it should be ok...but recheck another (chilled) sample 5 days later. If at day 10 the carbonation is still under, or is correct, it should be fine for the whole batch. If it's overcarbonated, vent the bottles. Depending on how overcarbonated it is, you might only need to do this once. Again, check another sample 5 days later.
What I said above sounds like a bit of stuffing around, but imho it's worth it for the peace of mind in knowing that your bottles are unlikely to go bang. But still keep them in a place where if they do go bang, it's not going to hurt anyone.