Thanks all.
Temperate water tanks can be split into two sub sections I think:
Cold water. These tanks house flora and fauna found at depth in the ocean and require stable, cool temps. Steve Weast of "Oregonreef" keeps such a tank and maintains a constant 55*F.
Tidal or transitional zone tanks. This is what I'm after. These tanks house flora and fauna found on the margins of the ocean (tidal pools, mud flats etc...). While the overall temperatures are much cooler than tropical systems they do vary from season to season and from tide to tide. Some examples of these species are: Sculpins, Tubesnouts, Gunnels, various crabs and snails, Barnicles, Limpets, various shellfish, Pacific anemones, Starfish, various seaweeds and macro algaes etc...
Few people keep coldwater tanks and fewer, tidal zone tanks so this really is a bit of an experiment. My plans are modest for this tank; a few rocks with macro algae, some eel grass and some wildlife. I mainly want to see how all the mechanical components work together and gain an understanding of climate and feeding requirements while I construct a larger tank to replace the 135G.
Here is a sketch of the current plan
and the tank after cycling for two weeks
Here's the backside (no surge tanks yet). I've removed the workbench for more room. I also need (choke choke gasp gasp) about three more gallons of bio balls!
Here's a close up of the current sump
Notice how it sits on the 2X4's. In my quest to lower the tank temps passively I've decided that the sump should sit directly on the concrete to make use of its (the concrete) natural cooling effect. This sump won't fit between the 2X4's so I've put out my request to the hobo gods and soon expect a 55G. long to magically appear. When it does I will get rid of the temporary submersible return pump as it is adding heat to the system. The permanent return pump will be in line, not submersible. I will also do away with the small skimmer feed pump as it too is adding heat to the system. It will be fed by a line tee'd off of the main return line. Actually, everything will be driven off of one main pump with no additional powerheads etc... I want to reduce my heat input as much as possible to either avoid a chiller or, if neccisary, to use the smallest HP possible.