need help with venting

i have a 4x4x8 tent with 3 6" outlets one 90 at the top left corner one directly behind the top duct on the back wall and one on the front left corner at floor level.
im current running a 600w hp cool tube the setup goes cool air in from bottom vent then through tube and out through top 90 vent. but my temps are still high. i have vents open on the bottom. but nothing sucking in.
i just also bought another 6" uinline fan coming tomo trying to figure a good setup
should i use new fan to force air in from bottom vent and use the top extra vent to suck air for the cooltube?

it sounds like your cooltube has lots of curves and barriers in it. 90 curves diminish venting so much. you should use big enough duct for cooltube and place exhaust at its end. also it is better to place fans as exhaust and use passive intake. your inside temps must be like 6-8 F above the outdoor temps, at least that's how it is in my room

No tube from intake to cool tube right?

Are you using powerful centrifugal blower or a little booster fan?

booster fan 240cfm and it is suck air from outside then into a duct straight to cooltube then out of other end through a duct to another room.. also a small pc fan in the other duct at the top exhausting hot air until the next booster comes tomo.
not sure wether to put intake for cooltube up top(where pc fan is) and the new blower on very bottom blowing in

Those fans are pretty weak. Remove intake hose. Let air from tent go into the reflector and out thru blower. Due to negative pressure, fresh air comes into tent from opening in tent down low. This ventilates tent and cools hood with one blower.

Toss the booster fans and get a vortex. Your never gonna make those do the job.

since i have two now can i just mount the second one up top keeping the current setup intact and the the fan will suck fresh air through the mesh vents at the floor leveel

i agree those booster fans suck and not like they should. I believe i have one somewhere along my ducting to boost my 4inch inline but hell i fart harder then it blows air so i would have to get up above my tents and actually check it to find out.

sacrifice the 50bucks and get yourself an inline fan & do not buy one of those cheap fan speed controllers you will just wreck your fan IMO. If you need to slow it down get something to reduce the power not just slow down the rotation.

If you neef a fan speed control, get one that is sine wave or the fan groans at reduced speeds due to the squarish waveform. Sine waves are what an AC generator puts out and what AC induction motors are designed to use.

Are you saying there's only 3 vent holes in the tent? If so you can't run two fan circuits. That leaves you pulling air through a filter into the cool tube and out. Use the lowest vent for passive intake, coolest air and slightly higher co2 content.
I thought most tents had 4 vent holes so you could run two fan circuit. Two 6" fans would easily solve your problem if that's the case.
Fred