well its that time of year. upgrade and maintenance time. lately my liquid cooling system's performance seems sub par. due to a few of factors i knew about and one i didn't know about. 1. my flow guage has stopped working which is likely a flow restriction. 2. i think my pump is dying bc at full power it seems to only cool about 60% of what it used to. 3. massive dust build up on the radiator which probably reduces it's efficiency. 4. the one i didn't know about...it looks to be sediment in the coolant. did a little reading and it appears the recommendation is every 3 years for coolant replacement. it has been 2.75 for mine. anyway i recently purhased a new gpu and just installed a new cooling block so i have more load now which consist of a 965 be and 2 6870's cfx. well since i had to drain the system anyway i decided to completely tear the machine down and external lcs down and maintenance it. i have a koolance exos 2.5 btw. i removed the flow meter and after flushing it with water noticed it began to work flawlessly again but decided against it bc i feel i was tricked by a marketing gimick. i can tell by my temps how my system is doing and do not need any little spinning du-hickey. when i drained the coolant i noticed that sediment i was talking about so i decided to completely flush the cooling system. during the flush procedure i noticed the pump seemd to perform better(by sound and the amount of h20 it was spitting out seemed to increase noticably). also installed a second in-line pump but havent brought it into the loop bc it needs additional fittings; however i may abort if the system works efficiently as it is once re-activated. the coolant i have is clear and i have been able to salvage about 50% of it by siphoning from the top as the sediment goes to the bottom if allowed to be still and seperate. i may be about to get another 10-20% after it settles again. i will use it as backup colant for emergencies if needed. im just waiting on the new coolant to come in the mail to re-activate the system. questions i have is: am i being too optimistic in hoping the pump will start working more efficiently since i have removed all the sediment or is the pump screwed? ill know one wat or the other once i bring it back online bc the system was operating at max capacity with just one liquid cooled gpu. will that sediment cause the pump to function less efficiently? seems it would cause the coolent itself to be less efficient by counteracting it's ability to transfer heat. should i add a second res. the one in the system is kinda small i think. any other input would be appreciated. thanx.