Bourgault tank leaking grain into airstream

With so many size differences in seed these days and some companies rip us off on size instead of weight on canola seed you need good precise calibration and a lot of sprockets on hand or a transmission that can fine tune the flow of seed.

On my jd 1910 cart one click on the transmission is .3- .4 of a pound .
That is as low of a change I can do on the transmission .
I find the jd calibrations runs about 8% faster so I adjust based on that .

I remember in the old days seeding with 36 Massey s and than the big step up to 360 Massey discers we used a 72 tooth and a 12 tooth sprocket ! No calibrations back than . Just trail and error .
We also added insecticide granular to the seed to dilute the rate down !
Can anyone remember what the name of the redish pellets insecticide granulars were called ?
Memory says it worked way better than what is put on seed now but I think it killed the fish which is not good .
Somebody on here will remember !

When I ran my 4350 cart I remember having to run to the dealer for different numbered sprockets . Had quite the collection on the shaft holder ! Good simple tank .

I am the opposite , I calibrate quite often . I right down each one over the course of the season .
My oat calibration stayed pretty steady all thru seeding which gives me confidence everything is working right . Lots of guys complain of bridging in oats on there jd air tanks. I do cycle the gates often and try to seed out the tank empty between fills .

But I know the first day , calibrations can change over 100 acres .

I have a 6700 tank with a PDM pro low output auger and easily putting down 2-2.5# of canola and it's been pretty accurate on canola and inoculant and grass seed. Not sure if that auger would work for higher rate stuff or not. I always do a stationary calibration and it runs about 7% higher in the field usually. 
When I had a 3225 it was not super consistent as I recall, the rate often wanted to climb. But it had a double flight auger only I think.

Stationary calibration on our 7700 tank and on the 6450 before that. On our 2155 and 3225 tanks always did a moving calibration. Had a line on the tire of the tractor dad would count the rotations of to get the feet before we had gps with a foot counter. We never calibrated canola on our 3225. Just used last years setting and put two bags in and see how many acres we would get. The low tank alarm would go off with 1 bag left in it. So if we got 10-12 acres it was good.

3225 had the granular tank that we used for canola so you could set the rate way slower and independent of the fertilizer. It had two different clutches on it so you could set two different rates and flip a switch to change. We had one for canola and one for corn. Neighbour is still using that tank and is still working good for him.