Will suspended sediment affect a hydro reading?

Will suspended sediment (yeast, ect...) affect a hydro reading?

My carboy was getting too cold (despite me turning up the thermostat) so I put it in a bath of warm water, this of course started some convection and stirred up the stuff on the bottom, I took a hydro reading a few hours later, and wonder if it will be valid to determine if fermentation is done/

Yes, your reading can be off if there is too much stuff in suspension.

If in doubt, just leave it sitting in the hydro overnight, to give it a chance to settle out again, then check the reading again in the morning.

I had a really messy brew on Sunday: a partial mash Kolsch, got a stuck sparge, never did manage to get a clean recirculation and ended up with a ton of gunk in my wort. At pitching time my hydro sample read 1.051, which indicated 90% efficiency: that would have been nice, but unlikely based on past experience So I left the sample sitting in the hydro tube in the fridge overnight (this was before pitching, so there was no chance of any fermentation kicking in). The next morning I had a nice layer of gunk in the bottom of the tube. Warmed it up again, repeated the measurement, and I got 1.048, bang on my prediction.

How much of a difference will you see from the yeast and stuff, yesterday it was 1.021, today it was 1.019, is that accounted by the sediment settling, or is it still fermenting?

Probably a little of both. What was your FG suppose to be?

I dont know, the kit I got was a "beginners kit" so it didnt really have any of the specifics to confuse me.

Just to be on the safe side, I would give it another week or two if you don't know what your FG should be. When in doubt, wait it out!