Bow Valley Tank, Setup Questions

[Cyclo]

Im buying a used tank that was made at bow valley. I want to drill it but I don't know if the bottom pane is tempered or not. Do you guys know if they use tempered for the bottom glass?

Also is 5 holes (6 if the bottom is tempered) in the back too much for 3/8" glass? The tank is 30x24x20. The closed loop will be 3 holes, and 2 return holes from the sump.

Also I want a black background, but also an external overflow box? Is there anyway to acheive this? I'm thinking a black acrylic insert across the back is my only option. My concern is water become trapped between the acrylic and the glass unless it was glued in perfectly.

[Delphinus]

Ok .. um ... my guess is that I think Bow Valley would not put tempered on the bottom unless it was specifically asked for by the original purchaser.

Supposedly the way to tell if you have tempered glass is to look at it with polarized glasses, if you see a wavy pattern then it's tempered, if not then it's not. I know that when I wear my sunglasses outside, because they're polarized lenses, when I look at car glass I can see this wavy pattern that is otherwise invisible to the naked eye. It was freaky the first time I saw it, I was like, what the heck is wrong with my glass? And nobody understood what I was going on about. "Look at this window!!!! Why is it all checkered?!!!" Um, anyhow, there you go, try it if you got 'em.

As far as the number of holes, personally, I don't know if the number of holes so much concerns me as much as the placement of holes. Closer to an edge should be OK (not too close though otherwise there is risk of cracking while drilling), but close to the centre of a pane makes me nervous since that is the spot most likely to endure the most amount of flex when under load. So basically it's about placement and spacing.

As far as black acrylic, I would think that as long as the edges are glued in then there's no huge need to worry about water in between. Over time it will likely work its way in, but you shouldn't be able to see any discoloration when looking at the display part of the tank (you might when you look at the back of the tank). Bow Valley does this sometimes so you could ask for their opinions and so on.

I'm not sure I understand the question about the external overflow. Should be no reason you couldn't do an external overflow. One way is to have the box or cup mounted on the inside, then a bulkhead for the pipe out the back. Or an overflow box using U-tube(s) that go over the tank edge (just need enough flow through a U-tube to ensure that air bubbles get cleared, rather than get a chance to accumulate and break the siphon).

Hope this helps.

PS. I'm going to move this post into the main reefing forum. The post will get exposed to more traffic and thus hopefully more people can chime in and elaborate, or answer better than I did, or just correct me if I was mistaken anywhere in the above.

[danny zubot]

If you want to know for sure about the tempered glass you could just call them. But as tony said, I don't think the use tempered anyway.