Well I spent a few hours rebuilding my loop, identically, a few different ways and I feel like Im in the damn twilight zone.
I took everything apart and checked for clogs. i didnt see anything, althuogh I did see a bit of teflon tape that was showing through into the inside of the joints of the fittings, that I thought *might* possibly have something to do with the slow down. I retaped the fittings put everything back together identically to how it was and started the system. My flow was now DOWN from the 270s to the 250s!! I then saw a little bit of water dripping from the intake of the first pump and figured I was losing water pressure due a not quite closed loop. I tightened that up and flushed the system again with 2 gallons of distilled. I was now up to the 260s...but no 270s to be had
Certainly, nothing in the 280s to 290s.
I decided to change the output of the reservoirs to see if that helped. Instead of some two outputs with a few inchines of tubing into a Y connector at the pump inlet, I used a T block to make one output into one piece of tubing straight into the first pump intake. This was a much different initial result. I was back up to my original speeds around 310 LPH for about 30 seconds, then 205, 295, 285, 275. Then I noticed water dribbling out of one of the EK reservoirs. turns out screwing in the joined T connector, I stripped one of the outputs of the EK. It was toast, no amount of teflon tape helped.
So, I switched to a single reservoir, flushed the system with another 2 gallons of distilled water and changed the line into the rest from a Y connector, to a single tube in. I was interested to see how this would effect my flow rate, i figured it would up the pressure quite a bit and up the speed a tiny bit. Well the pressure into the res definitely seems much higher, since its not be split from 1 1/2" ID tube into 2. The speed started quite high at 325 LPH, but within about 10 minutes was down to 275 LPH. When I came into the office this morning it was now down to 252 LPH!!!!
I really don't know what else to do at this point. out of curiosity, I've run the IBT using 27GB of RAM on all threads for the last 3 hours and my CPU core and package temps are 1 degree and 2 degrees higher respectively than my previous test, which may be too small to be an indicator of difference in water speed / pressure. CPU core temps (at stock) is between 43 and 46 depending on the core, while package temp is 50.
I dont like running on a single res as its pretty loud