I experimented, without a chiller and only fans running, temperature rose to 84 degrees. But at night the temperature actually rose. (You would think the opposite.)
Keep in mind the coral you also tend to keep.
Zoa's as we know can be more tolerant of higher temperature swings.
There is a very popular Zoa Collector/Seller in South Florida who keeps a tank in the garage and he says it peaks at 87 and his zoas do fine. I would paste the thread, but it wasn't stated on RC. Google: "Zoa's and high temperature." Maybe you will stumble across it like I did.
Chillers are expensive and be prepared for them to add about $50 - $75 a month to your electric bill if continuously running in the garage. (I am running a 1/3 HP.)
I would suggest you setting one up without a chiller and fans and see if some zoa frags tolerate it and keep us posted on your findings.
I have some really nice SPS, Zoa's, Chalice & Rainbow Acan's in my system, so I am a bit too chicken to try it.
If you do go with a chiller, make sure to buy some extra fuses for the chiller when they blow. You can buy them on EBAY 5 for $5.
I wish you good success, if you go this route. Setting up new tanks are always fun. (I hope you stay within your budget .. .. ..
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