Thanks for the link scavenger - just what I'm looking for!
D - No raining on parades here

Kicking the ideas around and looking for the weaknesses is an important part of designing. Better to see the pitfalls on paper (VDT) than afterward.
I'm committed to the C.W. tank but not the tidal pool per say. It is a design I've been kicking around in my head for a while and I may set it up barebones just to see what happens. I like the idea of putting a super slow valve on the low tide drain. The tank has 4 bulkheads in the bottom so one could go:
standpipe #1 - high tide drain
standpipe #2 - returnline (at or above high tide drain level)
standpipe #3 - valved low tide drain
Standpipe #4 - emergency high tide drain
As long as the return pump fills slightly faster than the low tide drain it will fill and maintain the high tide. When it shuts off the display will slowly drain to low tide.
I think I like it.
If one focuses on true ocean temps there isn't much variation granted but I have long suspected that intertidal species do tolerate a wide variation of temp extremes. I've noted this many times when I've poked about in natural tidal pools. A sculpin (for example) caught in a shallow pool will go from true ocean temp to quite warm in a matter of hours on a sunny summer day. The plan here is to only stock intertidal species.
Here are some temp ranges from the link that scavenger provided:
Arrow Goby: 4 -26C
Black rockfish: 10 - 17 and up to 22C
Grunt sculpin: up to 23C
Longspine combfish: up to 24C
Starry flounder: 0 - 21.5C
3 spine stickleback: up to 26C
Grunt sculpin
Mosshead sculpin
Tubesnout
or for the adventurous, Wolf eel
Photo's from hmsc.oregonstate.edu
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