I did a bunch of 25's today, which I don't do very often, and almost every time I was faster by about one second going from the deep end to the shallow end of the 25 yd pool I swim in. I'm not a gifted swimmer by any means, but virtually every time leaving from the shallow end would net a time in the low 19:xx range and leaving from the deep end was in low 18:xx range. These were with a pretty quick 3-4 sec rest at around 90% effort. Any reason this would happen??
I think this was the first time I've swum 25's since I started wearing a watch to keep track of pool intervals - I'm assuming there was this discrepancy in the past, but I didn't notice it by just glancing up at the pace clock.
Could you unconsciously be pushing off harder from the deep end, since you are not standing?
edited to add:
Turbulence must be variable in pools, but I can certainly see that jets aimed a certain way or in one lane or another, can make a difference. This is N=1 and you now must repeat the experiment in a different lane.