Right now I'm debating on wether to get a Res. Chiller or AC for my grow groom. It's getting hot and I'm now always throwing ice blocks in my Res. And was wondering which would be more effiecient, "cooler res. or keep ambient temp lower?

Its only now getting hot? Sorry, couldn't resist.
I don't know about efficiency, but my SWAG would be res. chiller. Plants can take some heat stress but roots will suffocate and rot in high water temps.

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cb
If you don't run, you rust. - Tom Petty
“From each according to his ability, to each according to his need”, a scheme to enslave the able to the unable. - Ayn Rand

guess it would depend on temps your dealing with. if res temp is the only problem then go with chiller but if have both room and res temp issuses then go AC

Having been thru resivoir heat problems before, I can tell you what I have found. The greatest factors on rez temps are 1) the ambient temp of the room the rez is located 2) the pumpimg of air thru the rez.

1) Take any bucket or resivoir and fill it with cold water and it will naturally rise in temp to room temp without anything else happening. If your light on temps are 85 the rez will soon be that, and the cooler dark period the temp will not go down that much.
2) Pumpimg air thru will increase this temp rise even more. Your air pump is taking ambient temp air (85 room temp) and compressing it which adds heat to it. Now you are pumping 90 or more thru the rez which will quickly add more temp to it.

Crabby is correct that the "above ground" part of the plant can tolerate more heat then the roots, but the ambient temp effects both, for reasons stated above.
Tiny's point is also correct, if you just need to get the rez temp down the chiller will work, and they use less energy then an A/C.

If you expect your room temps to continue upwards from what it is now then that will also become an issue along with the rez. then the A/C would make more cents (pun).

Only you can figure out which will be best for your situation. I'd start by locating the air pump outside the room to a cooler location, that plus the added tubing run might help bring the rez temps down, some.

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Keep it civil please, gentlemen. -stinkyattic
I think people should be educated to the fact marijuana is not a drug. Marijuana is an herb and a flower. God put it here and He wants it to grow, what gives the government the right to say God is wrong? -Willie Nelson

I would go with the A/C because it will help both ways. Unless your running CO2 then you need the ambient temps to be higher.

Ours stay at 72 degrees, water stays at 72. I looked at chillers but no amount of venting will help this heat 95 to 100 all summer and then lights on top of that. Some chillers only drop the ambient temps by 10 degrees. Still doesn't help me in summer.

personally I would also go AC but didnt want to make a choice with my first post since there wasnt enough info for me to go 1 way or the other with someone elses cash
btw good point Mac about the air pump .... never thought of that but boy it makes alot of sence

As I said I chased that ghost (heat) before in a NFT system rez. Had myself convinced it must be the submersible pump, even tho it was on a 1min on/4 min off cycle. Went to the hassle and money of getting an external pump only to find it made no difference in temp. Since temp ran slightly higher then room ambient I started looking at the air pump. Decided to experiment and placed it in a cooler with dry ice along with abt 10" of air line, soon rez was lower then ambient. I knew I found the problem then. Figured it was worth sharing.

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Don't touch my Willie - Kevin Fowler
Keep it civil please, gentlemen. -stinkyattic
I think people should be educated to the fact marijuana is not a drug. Marijuana is an herb and a flower. God put it here and He wants it to grow, what gives the government the right to say God is wrong? -Willie Nelson

Wow Awsome reponce! Thanks guys! All very good experiences and tips. My ambient room temp goes from 72-85. I have an ac duct in my flower room that I am going to try and split it to my veg room. I will try that but also buy the chiller. I am going to also post up a grow log of my first hydro grow and let you guys check it out. Will put up the link when I do!

check out my grow log

Ebb/Grow Buckets FF + AN Nutes "Grand Daddy Purple"