Plumbing...suggestions? Added a drawing...
 

I'm good at putting it together, but my plumbing ideas usually suck!!! :lol:

I'm going to use this style of external overflow:
http://i50.photobucket.com/albums/f3...p/IMGP3110.jpg

I have a 3/4" return, running a pump that will deliver about 700 gph. According to a plumbing calculator the minimum overflow should be 1.09". So I think I'm really pushing it to just use a single 1" overflow. So, should I put two 1" or a single 1 1/2"? I don't want anything in the middle of the back of the tank up high (esthetics), but I'm considering putting my return in the middle of the back down low say 3" off the bottom, then have two 1" overflows in each of the upper back corners. If I use two 1" overflows (which I'm leaning towards), should I use a single external overflow for the two across the whole back of the tank, or should each bulkhead have it's own external overflow?

Good idea? Bad? I dunno...? Suggestions?

I don't see many people with check valves on their returns, but I think I will. Is there any reason not to?

Also, can you guys post some pics of how you've incorporated a waterchange valve or some such into your plumbing?

The only problem I see is, If the power goes down you’re going to siphon all the way down to the level of your return. A closed loop return down low would be fine, but not a sump return even with a check valve, they have a tendency to fail, it doesn't take much to keep them from closing all the way. This is assuming that your return is through the tank not over the top.

Ah...good call.

Rather than a bulkhead to feed the external overflow do a single large notch the width of the box or a series of smaller one (see picture in this thread).

And make a Herbie, drilling the external box for two holes. In your picture the air being pulled into the drain must be making an awful sucking sound.

I don't know how to do that to glass, and I don't want to risk breaking the pane. what's wrong with using a bulkhead?

Yes, now that I think of it, I've seen a couple plumbed kinda like that, and they were very noisey. I've heard lots about Herbies, and I have no clue what they are. I'm going to go researching. :D

Take any overflow box - internal or external, doesn't matter - and drill two holes in the bottom (holes will be in the bottom of the tank for an internal box). Put an ordinary standpipe in one hole. Leave the other hole as is. Put a gate valve under the no standpipe hole and adjust it so the water level in the overflow box is just seeping down the standpipe. Voila . . . dead silent overflow a.k.a. a Herbie.

Ya, I went and found Herbie's original post on Reef Central. Cool idea. I think I'm going to go with that. I think I may just do a u-tube type return as well instead of drilling a return hole, but what are the pros/cons?

I don't know how to make overflow "teeth" in my glass panes though...I imagine the teeth would just break off?

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Ooh man, where to begin.

First of all, do the notched overflow if you can. I would have, if I would have thought of it at the time. (BTW, for those of you who don't know, that pic if of my tank) When I picked up my tank from Bow valley after they drilled it, I saw a notched overflow on another tank they were working on, and loved it. But, too late for me I guess.

Secondly, if you are thinking of making the external overflow out of acrylic, think again. Acrylic warps under the heat of any lighting really. What you see in the pic is what I had, and it failed. It actually started to peal right off of the tank. I should have made it out of glass. The design is sound, but my execution of the design back fired totally. The adjustable standpipe worked well, but it was noisey. Adding a Herbie to the standpipe would be a great idea. I never thought of that at the time either, probably because the tank is in the basement and I don't really care about the noise.

I have since added a check valve to the return, but only because my sump was about 1 gallon shy of being able to handle the water drain off.

I don't know how to do the "notched" overflow on a glass tank. My tank is rimless, so that's not a worry, but I don't think I could cut/drill those notches without them breaking off...that would REALLY suck.

I'm going to be making glass overflows, but thanks for the heads up. :)

Ok, so here's the best I can do with the software on my puter.

The "PUMP" is a Poseidon PS3 which should give me about 700 gph at the 4'6" head I have. Sump is a standard 25g tank, which barely fits in the stand. The return is 3/4", and there is a check valve just above the pump. The overflow is a 1 1/2" bulkhead to an external box with 1 1/2" Herbie style drains w/ gate valve. They drain into the same chamber the skimmer is in through a CPR 4" sump inlet assembly w/ filter sock. The refugium on the right is fed by a small pump (MaxiJet 1200 maybe?).

http://i85.photobucket.com/albums/k4...2/Plumbing.jpg