Ok bud let's se how much you can soak then cuz this information needs to be somewhere on here anyway not sure why no one knows this stuff it's botany 101 let's start with a little more detail on measuring humidity properly
Relative humidity control is an essential part of insect and fungal control, as well as plant uptake and growth. Humidity above 80% dicourages spider mites but promotes fungus, root rot, and stem rot, humidity below 50% level reduce your chance of fungus and rot. Measure relative humidity with a hygrometer as stated before this is an extremely important instrument that will save you and your much frustration and failure. By knowing the moisture content in the air you can much easier keep it at a safe 50% level. There are two common types of hygrometer, the spring type, wi8is accurate within 5-10% this one is inexpensive and just fine for hobby gardens where the main concern is to stay at 50% RH. There is also a psychrometer (hygrometer) it is more expensive but is very accurate and measures with a "Wet bulb Dry bulb" calculator, then you have a humidistat this is simular to a thermostat, but regulates humidity instead of temperature. Humidistat are wonderful and make controlling RH much easier but can get on the pricey side for one with day/nite options witch i recomend. Another awesome thing to use (this is a grower secret shhhh) are these little packets called desiccants the things u get in new shoes or beef jerky packets you will have to find out more or where to get them yourself. You can increase the humidity in a room by simply misting the entire room with a spray bottle or putting out buckets of water to evapote in the room. You could also use a humidifier like the ones used in your bedroom for Vicks when your sic, this is not necessary unless there is an extreme problem with the room drying out to much. And as stated before best options is a dehumidifier with a blower fan in it. However Young seedlings and and rooting cuttings thrive from 70-100% RH
Let's talk in more in detail about CO2
Carbon dioxide (CO2) is a colorless, odorless, nonflamable gas that is around us all the time. The air we breath contains 0.03-0.04 percent (300-400ppm) CO2. Rapidly growing plants can use all of the available CO2 in an enclosed garden within hours. Photosynthesis and growth slow to a crawl when CO2 levels drops below 0.02% (200ppm). CO2 enrichment has been used in commercial greenhouses for more than 40 years.
Adding more C02 to your garden room air stimulates growth to the highest rate possible. Indoor growing is simular to conditions in a greenhouse and usually apply the same rules and principles . Most plants can use much more CO2 than can be provided naturally, As i stated before CO2 can be increased by as much as the 0.12-0.15 percentile (1200-1500ppm) The optimum amount widely agreed upon by professional gardeners., plants may grow as much as two or three times as fast when done correctly providing light, water, and nutrients are not limiting.
CO2 Has little or no effect on plants grown under florescent lighting, it simply is not powerful enough you must have HID lighting or you are wasting time and money in your efforts, as for a garden room using CO2 enriched air with appropriate RH, adequate lighting, with scheduled water and nutrients, can have superlative results.
In fact with this basic combination, most evey plant will grow much faster and more efficiently than they grow outdoors.
The old wifes tale, "talk to your plantsthey will grow faster infact is true the trick is knowing their language."
CO2 enriched plants demand a higher level of maintinance than normal plants. They use up nutrients wayer and space twice as fast as normal plants a higher temperature of 85-87 degreese F, will help stimulate more rapid metabolism within the super enriched plants.
Properly maintained the plants will grow so fast and take up so much space, that flowering will have to be forced sooner than normal. like foliage, root growth is also simulated by CO2 enrichment it is taken via the leafs and the overall growth to be transferred to the roots, this being the reason they use so much more water and food, and in contrast CO2 is actually helpful in conserving water used by plants, water rises from a plants roots and is released by the same stoma that absorbes CO2 during transpiration. To stay up rite and turgid, a plant must balance uptake and water with the amount released through transpiration.
CO2 also effects plant morphology and makes the cells of plant parts more densely packed together, flower stems carry more weight without bending, and commonly have more node spacing as well, because of this some growers get frustrated using CO2 as it causes plants to grow so fast, unsuspecting growers are unable to keep up with them, CO2 enriched plants that do not have proper support of the other critical elements for life, will not benefit at all and the CO2 is wasted, this can be caused by only one of the critical factors.
Increasing light intensity in a CO2 enriched room by adding another HID lamp helps speed growth as well, but could possibly make them grow so fast it will be impossible to maintain.
To be most effective the CO2 levels must remain at or around 1500 ppm to accomplish this the room must be completely sealed/enclosed all cracks and gaps over one-eighth inch must be sealed off to prevent CO2 from escaping you will also need a vent with a baffle to remove stale air that will be replaced by CO2 and will not let it escape