Show us your cool tube setups. Let us know if they are doing their thing.

My temps got way too high. Like 38c for a really short period of time. So refigured my airflow and cooling and seems to be helping. Still gonna throw a couple of co2 bags in for good measure though. Any tips. Tricks. Suggestions are very much welcome. I also have an 80w greenhouse bar heater I'm about to wire up to a thermo relay for lights out. First grow by the way everyone.600w dual spectrum hps. 6xbagseed (stardawg) 3 were stunted purposely for a month due to space issues. 3 already flowering for a month. (still waiting to see if the other 3 are fem) In soil using ionic nutes. Additives have been so far. Nitrozyme in veg. Super drive and calmag mag have played a part throughout. still very much feeling my way around at the min but loving the experience so far.

You have Filter -> Fan -> Piping -> Cooltube -> Piping -> Exhaust. You are removing the hot tent air thru the very hot cooltube air.

Another way yo go would be get another fan.

Intake Fan -> short Piping -> Cooltube -> Piping -> Exhaust. Air from the outside goes thru the cooltube and out. no need to filter it.

Then do Filter-> Fan-> Exhaust. This one gets rid of the heat in the tent. Bonus points for setting it up the fan motor is out of the tent (another heat source).

I tried a similar way to your suggestion using 2 5 inch intake fans and ducting either end out of the tent. One pushing one pulling the other end. Temps were about 28.4 using that system. I'll show you. One sec. The way I'm going at the min has got me down to 24c. Which I'm comfortable with. I know it's not ideal but filtered air is leaving where it should be and so is the heat from the light without having to use an extra fan and y splitter on the duct

What do you reckon to another 5 inch intake fan outside the tent on the duct pulling the air to ease the stress on the filter fan motor. Thinking faster airflow. Less time for temp increase?

I don't like what you are doing there, you are creating a neg vacuum that is drawing in "unfiltered air. SO if your tent is sealed properly then it will get all sucked in , and fight your cooler fan. If you leave your tent open you are getting air in from what ever dirty place that you set the tent up to avoid. I recommend draw the air from outside the tent push though the cool tube then vent it out side the tent. Get a different fan to exhaust using the filter and even better have an intake fan as well with a filter. so go get one or 2 more fans and a cheap furnis filter. Positive pressure in the tent is better then neg pressure. You have better control of t he environment, though you might need neg pressure to deal with smell
.

also a bit of trivia, blower fans like to have a load on them they use less electricity and run better.

I do need the negative pressure in the tent. Smells a big issue as neighbours are close by and temps are too high without windows open. Ducting goes out and across the room and close to window with a thin pair of tights over the end to stop any insects getting in. I've heard mj likes to grow with negative pressure too. Ideally you are probably right but many many things restrict me from doing many things

Am I right in thinking a fan blowing is more efficient than a fan sucking? I know the filter fan is sucking before blowing but it's blowing at the point of its 2nd use to cool the air in the cool tube?

still figuring shit out as I go along me mate so bare with me

No worries , fans usually pull a little better then they push, but not enough to make a design change if you have other ideas. I am here for you bro anything I can do to help

Space is my main limitation everywhere. 2 sides of the tent are facing walls. Half the door is covered by drawers. And Colanoscopy juniors stuff takes up 99% of our home ha. Much appreciated too on the input. If I had my way I'd sink a storage container somewhere and use that as a grow room. For now. It's making the most of what's available and a 4degree c shift in temps since swapping means I must have got something right ha

Well, if it works it works. There is so much gear that is necessary for a proper grow it is nice if you can skate by with something that is not technically right but works. But I did like the old version better I wonder why you have such a difference ? Co 2 as you mentioned that you are adding will do wonders for you as well

It's never gonna be an exact science is it. But it's fun tinkering anyway. This works better than it was at least and the co2 should be in the post soon so I'll keep at it and keep yous posted