I would like to give it 5 stars, but I can't as the black spunge are whirled up into the reservoir if you use one of the 2 side ports. The black spunge also floats to the top when your pump is turned off, and it does not get sucked back down even with very powerfull swiftech mcp 35x pump Only way to keep it down is to make/buy an inner tube that physically holds it down. All of the above also makes it hard to bleed (get the air out), as the reservoir instead churn air into the loop!! If you use the top port as inlet it is hard to fill in water as needed, but if you use the top port as inlet AND make an inner tube straight down, to hold the spunge down, you get the BEST performance of almost any reservoirs AND it bleeds very very fast.. so 4 stars even though it has some major issues.