[Delphinus]

On the bright side at least it's not a complete showstopper. While it does mean I have to stop filling for the moment, at least in the meantime I can get to work on powerhead placement, wavebox placement, and flow tuning ... as well as work on getting the electrical plugs all sort of tidied up and so on. Plenty things to work on it seems!

I can also take the opportunity to redo the overflow plumbing to account for a gravity feed for the skimmer. The only thing that I wonder about this is if I run a frag tank, as is the plan, then water entering the frag tank drains into the sump completely bypassing the skimmer. Water would have to re-enter the display tank, work its way through there and only then drain into the skimmer. So it's as if to make the display tank skimmed really effectively/efficiently, I have to make the frag tank skimmed really ineffectively/inefficiently. The flip side to this is that frag tank is only 40g and presumably only houses corals or some small fish and the display tank is going to have the heavy poopers, so maybe this is a negligible concern.

Two alternatives that I can see at this point are:

1) "T" the drain pipes from the frag tank and the main display together, and then route into the skimmer.
Pros: Both tanks get skimmed the same, cheap use of an available resource (gravity)
Cons: The skimmer has a 1" input. I have doubts that at only 5' of head pressure or thereabouts that this is enough "push" through the restriction to get enough gph through the skimmer. Also if the two drains are connected together then there is a risk that the frag tank, which sits lower than the main display, is at risk by sitting in the "flood plain" should anything cause a blockage in the skimmer, or even just a backpressure buildup, and water goes downhill and so could easily end up in the frag tank and overflow. There is an emergency overflow on the frag tank (it will be a Herbie overflow as well) but in that case it's only 1" and I think a 280g draining is too much for a 1" pipe. Hmmm I might have just convinced myself this option is a no-go.

2) Use a pump feed in the sump.
Pros: Easy and quick solution. No pipe rework. Both tanks have "equal-ish" access to the same level of skimming. No worries of one tank causing a flood in the other.
Cons: More up front cost (purchase a pump), more electrical cost

However ... "Corollary pro": The sump is already drilled for a pump. I have a Mak4 pump that has a good impeller but a shot bearing, Stircrazy has a Mak4 pump with a good bearing but a shot impeller. Perhaps the writing is on the wall here, I just have to convince myself that I'm ok with the costs and move on with things.

As for the glass, I've started looking around. So far the best option for purchase is Bow Valley. You could hear their disapproval in their voice about the size and thickness of glass, and I suppose I could take the opportunity to bump up the thickness now, but it seems to me just wasted money if I'm not replacing all 3 sides of the sump. That said, maybe I should see what it would cost to go to 8mm, leave it at that, if ever another side breaks then I bump that panel up to 8mm and so on and so on. The best part about BVA though besides being the flat-out most economical vendor, they'll do it while I wait. Everyone else I've talked to so far is all "it could take up to a week".

@Michika - thanks - if you wanted to check your basement or something, what I need is 60"x18". What's on there now is 6mm. So anything that thickness or larger. I'm kind of thinking it's a long shot you have anything like that, so no worries if you don't, but for sure, for now I'll hold off visiting BVA until I hear back from you.