Reverend can you explain more how your plumbing setup runs. Also where in line is your chiller? What is it set to? Where are your heaters in the same line. What are they set to?
I am looking to connect a 65g system which will hold seahorses if I can get it dialed in right to my 125g reef and have them share a common 150g sump.
I think the 340g of water volume will do well to help to dilute the bacteria's involved, but having two tanks connected at different temps is intriguing. I would like to know more.
its pretty crude actually but it works for me.
i find the heat generated in my system mostly comes from excess heat from koralias/powerheads (i have 5 running all the time in my DT) and from the lighting in my DT.
so this keeps my DT warm during the day. water goes down from overflow in DT via gravity into FUGE1. since my 1st fuge is run on an opposite lighting schedule, as the water sits in the FUGE1, it kinda cools down, especially since the flow in there is low. also, FUGE1 gets a constant drip of top off water, which is also cooler water.
from FUGE1, the water is pumped up to FUGE2, which is essentially the SH tank. if you have a chiller, this is the point where i would connect it and set it to a lower temp for the SH and then have it pump into your SH tank. i don't own a chiller but this is what i would do if i had one.
the water from FUGE1 is pumped up to FUGE2 (the SH tank). this water is already cooler than my DT, but is further cooled by 2 Arctic Cooler fans which i DIY made using Melev's cooling plans pointed directed at the surface of the water.
of course there is very little flow in my FUGE2/SH tank so it also stays cool in there but the fans make a huge difference. in fact, i used to have the fans on 24-7 and the water in FUGE2 was almost too cold (65-68) so i put a variable timer on the fans (on/off for 2-4hrs here and there depending on time of day) and now i've got a happy and relatively consistent temp at 73. from FUGE2, i have a gravity overflow that has them go back into the DT. its very slow so the water in the DT doesn't seem to be affected by the cooler temp water flowing back into it (except at night, so i run a heater in the DT).
hope that helps! just some other things to consider, i have 4x65W T5 lights + some LED in my DT, FUGE1 has simple old skool T8/12 lights, and FUGE2/SH tank has 70W K2 Viper MH. all my tanks are open top so no covers. i also get alot, i mean alot, of evaporation since i added the fans. both Fuges have a variety of macro, live sand (DSB in FUGE1), and live rock. i actually have to run a heater at night for the DT since the temp will drop significantly at night without a heater in the DT.
my main caveat to my 3 tank system is that there's a lot of plumbing, which i hated making. ive tested it for power outages and its all good. even if my mag drive failed i wouldn't get a flood. i have a lot of pod growth in both fuges. in fact the SH tank is filled with pods. i think my adult reidi dont care them at all, so its pretty packed with tinny little critters, some big and some small. they kinda look like a swarm of mosquitoes. actually, one night i saw a swarm of some bigger looking pods doing a weird swirly dance. every once in awhile, i blast the pumps so that some of them overflow down to feed the DT with some live pods.
good luck!