If you don't mind me asking, what weight/scale/recording system are using?
thankjs
I'm using this scale
http://www.lowcostscalescanada.com/MY-WEIGH-HD-300-HEAVY-DUTY-SHIPPING-SCALE-SC-HD-300.htm
It's under the hive, then all the cables go into a box beside it, currently in one of my surplus 5 frame nucs. Also in that box is a little computer running linux, which has a wifi link back to my network. A cron script runs every 5 minutes that reads the scale, then writes the raw reading into a database in a server in my closet. The scale is somewhat temperature sensative, but I developed a set of equations a couple years ago to compensate for temperature. I have a weather station running that's logging outside temps every 5 minutes as well, to the same database. The plot I posted is temperature adjusted data.
It's not lab accurate by any means, but, once the nectar starts flowing, there is no mistaking it in the scale data. Right now, they are burning it up as fast as it comes in, so I see a daily dip in the morning when the foragers head out, then it rebounds later in the day when they come home. Some days a small gain, some a small loss. But populations are growing fast now, so, I do expect to see the colonies starting to put on weight soon. By having one on a scale, I dont have to guess as to when that's happening, we will know right away.
I kinda kludged this setup together out of stuff I mostly had kicking around already. If I was going to do it again, from scratch, I'll probably put some effort into finding a scale that's less sensative to temperature swings. Particularly in the spring when weights aren't changing a lot, and temperature goes thru large swings, this one acts more like a thermometer than a scale, until one does a lot of math and figures out how to correct for temp. I'm sure my corrections are not spot on, but, they are 'good enough' for what I want right now. We are in a new location, and I really want to start correlating nectar flow with what's blooming around here.