Questions on CO2 and ventilation

[TrysHard]

I have a small 4'x4'x72" tent. I have a CF filter and fan of sufficient capacity to keep the air fresh in fact even on low it sucks in the sides of the tent, I keep it on medium. I figured that for such a small area I could use a homemade co2 generation with yeast and sugar. I have a pretty good technique and with 4 of them in my tent they are emitting about 3-5 bubbles a second of CO2 I have the hoses directed to the bottom of each plant. Anyone else with this sort of set up figured out the best schedule for running your exhaust fan and keeping your co2 higher? I don't have heat issues and can afford to turn the fan exhaust fan off as I have my light on a different ventilation system.

This is what they look like with the fan going all the time I think if I can get the co2 levels higher I'm going to have some massive buds because the stalks on these are huge and should support large colas.
Overview these have been in bloom for 10 days and are mildly super cropped. I am using GH 3 part and following their guidelines per this
chart.
Feedcharts

I just finished the transition bloom week four schedule and going to move to the early bloom formula. Just to give you more info to base your opinion. Oh the strain, Indica Blueberry. Told by the person who sold it to me that its genetics are from the original blueberry that all the Blueberry hybrids were derived from.
That's what they told me.
Big picture:

Some close ups of preflowers:

Top of one plant look how thick it is at the top!

This is a good 1/2" in diameter.

 

[TrysHard]

For perspective 5 weeks three days ago they were this:

 

[CO Finest]

Nice Intro. Plants looking good. I like to shut fans down a hour about four times a day while the lights are on for co2 build up better. Once again very nice growing.

 

[TrysHard]

Thank you. I'm trying for real quality first so I'm trying everything. This is my first grow on my own and its quite exciting! I will take you recommendation, thanks.

 

[CO Finest]

Well man you are looking good now. Strain,Nutes,lights and the right care makes the quality my friend. Do you know how much ppm of co2 you get in there?

 

[TrysHard]

Well man you are looking good now. Strain,Nutes,lights and the right care makes the quality my friend. Do you know how much ppm of co2 you get in there?

no I don't. The gauge is expensive, maybe after my first grow I'll invest in one. The secret to the do it yourself co2 is, leave as small air pocket in both the generator and the filter, and also don't put your tube that goes into the water filter bottle all the way down the jar stick it a little way into the water so it has less pressure to push against and it bubbles faster. You just need a water barrier for bacteria so it only needs a 1/2" or so of water. Make sure the connecting tubes are sealed perfectly I use a food grade silicone sealant and let it cure for a few days before use.

Yeah the're in my kitchen, I baby them. I fight myself to leave them alone all day during the dark cycle. I'm retired so I have time to take care of them.

 

[CO Finest]

Very nice. Your way is better then using soda water for sure. I like to use dry ice sometimes. That works great for me. I use co2 buckets in my veg room