Sealed Room with Portable AC? Still needs to have intake to get fresh CO2?

If I plan to use the portable AC I picked up recently (a Soleus dual-hose 14k) I was planning on having the intake/exhaust hoses ran into the adjoining loft/room...

I know the portables aren't 100% sealed and might have some minor leakage, so I have a 6" fan/filter that can be used as a scrubber...

Am I understanding correctly that with this arrangement I would still need to have an air inlet to get fresh CO2 into the room otherwise I need to invest in a CO2 rig?

Would I be better off having a passive inlet and use the 6" as both a scrubber/exhaust to simply create negative pressure bringing in CO2?

You are correct. In a sealed room you would need to supplement CO2 with either fresh air or a tank. "Better off" is a tricky term-- it depends on your experience, goals and constraints. I would say that a passive inlet is far less complicated and expensive. A sealed room with a tank has better pest resistance and get get you more weight if you have the grow perfectly dialed in.

I'm not a noob, but not a pro either. I would not go for a sealed environment for myself. I find the expense and complexity of it too much.

the space is a 9' x 5' approx. so I think a tank-based CO2 setup is almost too small for that space? Which means I would need to use a gas burner --- which means heat.

Now, I have a 14k BTU portable so I could deal with a little heat - but I'm not keen on the whole flame in a box apparatus... I know it's safe/built well/etc... but all the same it's unsettling for me...

So if I do go with some inlet, I could keep it filtered (i.e. dust shroom) and then use the 6" fan/filter exhausting out of the room to create negative pressure. Correct?

So I will need to have 2 inlets and 2 outlets... with 1 of each being used by the portable AC...

im in a tent and use a portable ac it's set outside the tent and i have no inlet just outlet im no expert
but my temps and humidity is just right and i didn't add any co2 supp i think the pac is giving enough fresh air to the tent
this sis my first time running a PAC but it seems to be working fine

i have run a very sealed 6x10 room for a few years now, and the first two years i didnt supplement co2, i just let them get it from me. i can spend just a few mins working in the room and ppm be over 1400. and i was pulling 20-24oz every three weeks.

So perhaps a tank would suffice? hell... even an Exhale Bag or two? I've also got a few 6 gallon carboys sitting around to do the sugar/yeast deal...

I would REALLY like to not have any exhaust/intake other than the portable AC.... keeping things as 'sealed' as practical...

I'm thinking one of these will fix my current heat concerns. the single hose 9000 btu is not
keeping up with my expectations.

http://www.amazon.com/dp/B0028AYQDC/?tag=hyprod-20&hvadid=15473472699&hvpos=1o1&hvexid=&hvnetw=g&hvrand=61855391267049603&hvpone=&hvptwo=&hvqmt=&ref=asc_df_B0028AYQDC

i really would not reccommend a portable ac to my worst enemy.

I haven't unboxed mine yet... Kept contemplating the split AC options... but by the time I pay for the HVAC installer and the extra refrigerant/line set I would need... I was up in the $1k plus realm...

So without going quite to that level, the 14k btu seems to be the best option... Can you elaborate on anything specific beyond what's been posted before? Specific bad experiences?

Seems the only real valid concerns I've heard are efficiency and that some models aren't "sealed" very well... I'm going to be using an open air loft for my intake/exhaust since I don't want to introduce moisture (condensation) to the attic by the exhaust when the temps are different... And the attic also has the problem of taking in hot air for the intake during the summer...

And as for outside venting options, in the wintertime I've heard the units will freeze up due to overly cold intake air... So using my living space for the intake/exhaust seems like the next best thing... and outside raises the odor control concerns as well... inside I can mask things a bit more... I'll have an air scrubber going one way or another...