Struggle too keep Plants healthy

Hi there. I don't know about CO2 as I have never used it but I have had challenges with temps in my tent too. I have managed to offset any ill effects of the temps on my girls by adding a humidifier. It won't lower your temps but it will allow your plants to transpire adequately. A good fan aimed at the light driver can help too. Some people disconnect the driver from the light and have it outside the tent although how they do this I don't know. Maxing the extractor fan helps too. A combination of the above can bring down temps even if you have to resort to leaving the tent door open a little. Bear in mind that changes to your environment can adversely affect your plants though. I use a handheld temp gun to take the leaf temp on your plants and then note your air temp and humidity in tent before referencing the following table. It will tell you if your plants are transpiring correctly for their current stage. https://vpd.aroya.io/ I have used this method to combat high temps quite successfully in the past but I have a small setup (2x2x5 tent and 200W light). Also, your leaf temp will be around 2 to 3 degrees cooler than your air temp so your ladies shouldn't suffer even at 29c. Hope this is some use for you and good luck mate.