Somewhat Newbie Needs help with Grow tent setup including co2 injection

Okay, I am about halfway into my first grow in quite a few years. I am a 100% legal caregiver for my cousin with MS. I am growing in a Grow Jardin 120T Dimensions are 4ft x 4ftx 5ft in the lower box and 4 x 4 x about 2 ft in the clone box on top. So far I have a 2 430 watt HPS Hortilux bulbs in a dual cooltube being vented by a Hydrofarm 400cfm inline fan. I also have another Hydrofarm 400 cfm fan on my carbon filter which I have exhausting out of my grow tent into my garage. There is a passive intake via 6 inch ducting on the lower end of the tent as well. The air from the cooltube is vented outside via the crawlspace in the garage. I also have an Air King 6" fan for air movement inside the grow chamber. The top clone box has a 125 watt compact fluorescent and is vented with a simple 8 inch turbo fan... Nothing else is really needed up there...

I am in week 2 1/2 of 12/12 in my flower chamber with one Casey Jones and one NYC Diesel. I have 3 clones of the Casey Jones and 2 clones of the NYC Diesel going in the clone box as well. I will include a few pics so you guys can have something to look at.

I am using all Foxfarm Nutes and Micro nutes, I bought the whole line. I am growing in Foxfarm Ocean Forest Soil in Root Pots.

Now where I have questions:

I recently purchased a Titan Co2 controller and soon will have a 20lb tank and want to incorporate the co2 into my flower chamber. I have read a lot on co2 injection in grows and all but havent quite got any info on a few aspects of it clearly. So here I am:

I am currently using a passive 6" intake and using the suction of my inline fan pulling through my carbon filter to vent the tent and get rid of the odor. Since I need to have a air tight grow space do I turn the carbon filter/exhaust into a carbon scrubber and just scrubb the air in the flower chamber? Or would I want to remove the carbon filter and place it outside the tent and scrub the garage surrounding the tent?

Temps are barely above ambient in the tent with the cooltube and inline fan. So I am hoping temps will not be an issue although I have never ran the flower room without the exhaust/carbon filter running as well as the fan going through the cooltube.

Do I need to replace the co2 or flush out the old co2 every few hours in the day during the light on cycle? Or just maintain the high 1500ppm level constantly???

Thanks to all who help me out here!!! Sorry if it is a bit long winded, just wanted to try to include all the info.

Casey Jones at 2 weeks flower


NYC Diesel 2 weeks flower

You want the carbon scrubber filtering the air in your grow tent, So run it and the fan inside the tent.

Ok good to know... I have read a little more about it all. I got my Titan Regulator in the mail today, hoping to have my tank by next weekend. I am still confused as I read on a few people threads about exhausting the co2 every 15 minutes to 1 hour and then replenishing it. Does the co2 get stale? Or am I ok if I just try to maintain the 1500ppm for the whole 12 hour period? ALso I Am confused about how and what to plug the regulator into. Do I plug it into a digital timer and run it for a few minutes an hour? I punched my grow tent size into a calculator on Greentrees and it said something like 5.76 minutes of co2 an hour on flow meter setting 1. I have a Titan Controls Co2 regulator how do I figure out what flow meter setting 1 is? Do I need more equipment than this? I really do not want to spend too much more on the co2 injection as it is already an expense that I really didnt need to incur but have always wanted to do. So how do I get my tent which is the Jardin 120 Twin 4x4 grow tent to my optimal co2 ppm ? What else do I need besides my Regulator, Tubing, co2 tank?

I ordered my tank online a few days ago. It is only a 10lb. tank but it was all I could afford at the moment. So, anyone on what else I need to make this work and monitor the levels of co2 in the tent? So far I have, I need to make my carbon filter that vents out of my box into a carbon scrubber to scrub the air in the tent for odor control and seal off the tent. I have a Titan Controls CO2 Regulator, tubing that came with the regulator and a 10lb. Aluminum tank coming in the mail. What else do I need?

i would have the intake for your light feed from ouside and exhaust outside sa well that can cool the light nonstop. next fan will be needed to clear out the room of moisture and gasses that plants sweat esentialy every few hours i have not read up yet on co2 saturation yet so not sure how often is the air should be changed but im verry interested in it cause i would like to get some good plans as well....Best luck on your grow Bro...

i went through the same thing dude if ur runnin co2 ina tent it needs to be setup cge style which means ur lights r cooled by a single fan, u need an a/c(usually u mite b abe to get away wit it in the right climate) to cool when the lights r on temps should b around 85 with co2, a dehumidifier is needed at nite when the plants r "sweating or transpiring". as long as the lights r sealed and the a/c has a intake and exhaust tube and u hav the dehumidifier u should b able to keep the climate in control and save tht tank but a 10 pounder isnt gunna last very long even on a 4x4 u mite need a second and try to go wit a 20lb if u can afford it.
hope tht answers a few questions for u man

Don't know if this helps or not but plants produce a little Co2 while they sleep so set your timer for 15minutes after your light comes on and 15 minutes before it goes off so they will use it all before they go to "sleep". Also C02 is heavier then oxygen so make sure you have it coming in your tent from the top (I have a small fan to try to blow the C02 back up). Hope this helps a little.