Grow tent running at temp 29c degrees

A friend of mine currently 100 x 100 x 200 grow tent, 400 hps but running temperature of 29c degrees and at 3.5 weeks of veg growth how does he bring the temperature down to 25c degrees?

thanks

get a cool tube hood to help lower a few degrees.
whats the ambient temp of the tent grow?
what kind of circulation/fans are you running?

I run a 4x4x7 tent with a cool tube. I have the same setup for veg as well as flower. I run/ran almost 7* hotter in flower. I put an 18" oscillating (not moving tho) directly under hood blowing across the bottom. this dropped my tent to 81. but, im also running in my basement, I have 3 ac vents open, 600w air cooled tube xl hood with 6" 440 cfm ventech fan 100%, a 420cfm intake fan-80%, a 420 exhaust fan-100%, and 3 clip type fans. see link below if you woild like to see pics of my setup and what not.

an ac or more ventilation. how warm is the room the tent is in?

Leaving the middle zip slightly open up top 3 or so inches will help or perhaps As demontrich said a air cooled hood or cooltube will help reduce temps ( if you aren't already using one ) .Also if I may ask is the tent being vented into the same room it's standing in/intake is in as this may also be leading to higher temps as the same hot stale air is constantly being used. When I first started out I was running 32 degrees in a 1.2x1.2x2 tent with a story similar to yours but running a 600w hps. The problem was easily fixed with some 3ply 6inch ducting as I managed to drop to a steady 25 degrees.
Good luck

Room temp is around 25-27c...London getting very warm these days lol , he has a 6 inch circulation fan but doesnt really use it too often, i keep telling him the temp is too high put the fan on full power And he has air intake and going out in the same room

room temp is around 24-27c 6 inch circulation is being not really being used but i keep on telling to use the damn thing. 4 inch intake fan what would the 3ply 6 innh ductling do? cool tube hood sound a good idea

roddyf said:

Room temp is around 25-27c...London getting very warm these days lol , he has a 6 inch circulation fan but doesnt really use it too often, i keep telling him the temp is too high put the fan on full power And he has air intake and going out in the same room

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that's his problem then. need to vent the hot air to another room or outside. cant cool the tent any cooler than the room its in.

^^^What Grorite said. He need to cool the air in the room for intake. If he has to vent the hot air to the same room, that's fine (that's what I have to do), but he has to run an air conditioning unit to bring the room temp down even more then.

thanks for the input