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Complete newbie requesting help with first octopus setup!

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D,
I found your diagram posted on the tank talk thread

Yeah, you thought that the nut was on the outside, but it goes on the outside. If you just swap the labels "overflow box" and "Acrylic Plate" the drawing will work.

One more important change. The nut must tighten down on a smooth hard surface that it can slide against, not on a rubber gasket (as shown n the drawing) which will cause it to stop turning, due to friction, before it gets very tight. The rubber gasket under the nut should be removed so that the nut can slide against the inside of the overflow box as it tightens.
 

djkaty

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Joe: the way I just did it now in my test was exactly that, on the inside of the tank it is just, in this order:

tank glass
overflow side
plastic washer (smooth hard surface)
nut

Edit: just looked at the diagram again. With the changes Joe just mentioned regarding the orientation of the bulkhead, I think your plans basically agree with each other now, and I agree too after my own experimentation the last days. I will use glass on the outside because I think it will probably look nicer and be more sturdy, plus I don't know where to get acryllic cut. I showed Thomas a hole saw like the ones someone here suggested and he confirmed it would fit his drill and he'd drill holes in acrylic for me if I wanted, but the glass I can do tomorrow at the glass master.

I'm really glad we've reached a consensus! :smile:
 
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dwhatley;161429 said:
...I don't know how effective the seal is using the nut vs the flange. I believe the nut is flush and would provide the same surface but it is hard to know without looking at the unit.
The nut side can't be sealed, only the flange side can be sealed. That's because water will leak between the threads of the nut and the threads of the flange (two hard surfaces with nothing soft between them will leak (unless under tremendous force, which deforms and mates the threads, as in a tapered PVC threaded joint))

djkaty;161430 said:
...the new glass piece _must_ go on the outside with the gasket after it to make a seal, right? Otherwise water will just continue to drip out of the larger hole as it was doing earlier in the week.
"by George, she's got it"

Dryness also depends on the seal made by the silicone glue holding the new glass piece to the back of the tank.
 

djkaty

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Understood. My neighbour who is very supportive will take me to the glass master (anxiety problems, it's within walking range) at 9:30 in the morning. The explanation about the drops of water sneaking under the gasket through the thread was the lightbulb, that was an excellent explanation as I had been trying to figure out in my mind exactly how the sealing worked and where the water goes. It is so obvious when you stop and think about it that of course if you slip on a gasket over a threaded tube that the water will go through on the inside side of it (I only thought about making sure the outer diameter of each hole was covered by a gasket, I never considered the part between the outside of the pipe and the inside of the gasket. Thank you!
 
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1.5mm is cutting it very close, but it could possibly work. Why not increase the size of the hole in the 60mm gasket by trimming say 2.5 mm off around half of it's circumference? Then you could slide it over a little and turn a 1.5mm overlap into a 4mm overlap without loosing anything.

The other factor is that the gasket is flexible, and so must be supported on both sides by rigid flat things. The gasket is meant to be squeezed between two flat surfaces that DONT FLEX. It is especially important that the meager 1.5mm (or 4mm) bit of gasket have hard flat surfaces directly on both sides of it, squeezing it. The flange of the bulkhead has a smaller diameter than the 60mm gasket, so you'll need to add a 65mm, or larger, rigid washer (with a 45mm hole in it) between the flange and the 60mm gasket, to spread the compressive force of the flange out enough to support the 60mm gasket. But wait! Remember that you need a soft rubber seal between any two hard surfaces to keep water out, so you'll also need to have a gasket between the flange and the 60mm washer I just told you to make. So the layers, in order, one the dry outside, are:
1) The glass tank wall
2) 60MM gasket (with enlarged hole)
3) 65mm (or larger) rigid washer with a 45mm hole in it
4) Original Bulkhead gasket
5) Bulkhead flange.

You can use 5mm or 6mm glass or acrylic for the washer (sound familiar). I guess this isn't saving us much, except that now, instead of using silicone to glue the new glass piece to the back of the tank, we are using a 60mm gasket and the tension of the bulkheads, so it can be more easily assembled.

I think you need the washers because the 60mm gasket will deform overtime if it's not supported on both sides, which will have the same effect as loosening the bulkhead nut.
 

djkaty

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1.5mm is the worst case scenario; if the offset is only 2mm rather than 3 then it will be 2.5mm, it was very difficult to measure with a thick tape measure - so the clearance could be anything between 1.5mm and 2.5mm on the 'thin' side.

However, you are right, the flange (all these new words lol) is about 2-3mm less in diameter than the gasket. So, I will continue with the plan and get the glass made.

Cutting the gasket up is yet another good idea I wouldn't have thought of, but it worries me a bit because I can't measure everything exactly and I will only need to make a small mistake to ruin it, especially not knowing exactly how much needs to be cut. However, if we're going to use your plan above and not silicone the glass then if I find it leaks I can always do that later I suppose?
 

DWhatley

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As an aside, I checked out most (I can't get easily to all) of our bulkheads and found that SOME of the nuts are flanged (allowing the bulkhead to be seated backwards more easily by providing a surface to seal with the gasket) and others are not but ARE using a rubber gasket on the outside (and in one case we have siliconed the bulkhead and nut like the post you found because the outer surface was a pebbled acrylic surface). What I did not find it the tank where we reversed the setup (either it is one that we have replaced or we ended up doing something else).
 

djkaty

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Morning guys (and girls!). I will be at the glazier (apparently in english) shortly. If anyone's still awake, can you give me some kind of foolproof way to make sure I attach the new glass in a level / correct location when I get it home? I have ruler, permanent marker, tape measure etc.
 

DWhatley

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Humm, your decorative backing is a problem that I just remembered. Does it come off? Did you decide to silicone the glass on the back? The glass will need to be against the tank, not the background.
 

djkaty

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I know, I removed part of the background a few days ago, that's fine. It's just duct taped on.

Anyway, glass not coming til tomorrow, their schedule was full today but I left the overflow box there and we wrote down the precise measurements. 44mm holes as that was the closest size he had. He had a 51mm hole cutter and apparently that is for electrical installations in Norway - so the original guy didn't use the right tool for the job.

I will silicone it onto the back, yes.

Exhausted... nap time.
 

djkaty

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For the first time in the 4 years I have lived here, I have just been informed that the property owner is coming to check the property tomorrow. We're not allowed animals... (or to smoke indoors). Crap, this is bad. And I'm not sure how to hide half a ton of water ..
 
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djkaty;161470 said:
Morning guys (and girls!). I will be at the glazier (apparently in english) shortly. If anyone's still awake, can you give me some kind of foolproof way to make sure I attach the new glass in a level / correct location when I get it home? I have ruler, permanent marker, tape measure etc.
FYI: in the US we say "glass shop" not "glazier".
The glass piece doesn't need to be level, but the overflow box does. You know, you don't have to glue the glass piece at all if you can find two gaskets that are a little larger than the 60mm ones you have. The 60mm ones might work, but I'd like to see more than 1.5mm of gasket width on the far side of the 51mm hole. Can you find some gaskets with a larger outside diameter? It doesn't matter much how large the inside diameter is, as long as it's at least 43mm. In case it's not clear, I'm suggesting that, instead of silicone glue, you use a gasket between the new glass piece, and the back of the tank. The tension provided by tightening the bulkheads down will hold everything in place, so you don't need glue.

If you decide to use glue instead, then I suggest that you:
1) Put the stand where you will want it to be, and put the tank on the stand.
2) Then put silicone glue on the back of the new glass piece, in a circular bead around each of the two holes (your really just using silicone to make your own gaskets).
3) Then assemble everything, including the overflow box, making sure that the overflow box is level, and tighten the bulkheads, but not very much, because you don't want to squeeze out all the glue.

Because the silicone glue is a thick liquid, you will find that you can slowly slide the pieces around a little. The problem now is that the weight of the pieces will tend to cause them to slide down a little which might cause the overflow box to end up out of level. To solve this problem, you can slide the pieces until the overflow box is level, and then quickly tip the tank onto its front (don't break the glass!) so that gravity can't move them. Then let the glue cure. Give it a couple of days to fully cure, then you can tighten the bulkhead a little more so that they put pressure on all the gaskets and make a really good seal.
 
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djkaty;161487 said:
For the first time in the 4 years I have lived here, I have just been informed that the property owner is coming to check the property tomorrow. We're not allowed animals... (or to smoke indoors). Crap, this is bad. And I'm not sure how to hide half a ton of water ..
If you're lucky, then this is just an unfortunate coincidence, if not then it could mean that somebody who knows what you are up to has told the property owner, and that they will specifically be looking for an aquarium.

Property owners especially don't like aquariums, because they are financially responsible for any water damage done to the down stairs unit in case of a leak, which can cost a fortune.

Your fish and live rock are in buckets, so you can cary them to a friends house or lock them in a trunk. You can drain the tank, plant some tropical plants in the sand and call it "a terrarium" (for which you have not yet bought the lid). That would explain the tank, stand, and lights. You would need to hide or remove all the other stuff (pumps, plumbing, sump) but that's not too hard to manage. The RO/DI filter is for filtering out all "the dangerous chemical additive that the government is putting into the drinking water" (it's better to look like crazy than guilty).

This might be a good time to buy a free standing armoire with a lock on it, to give you a place to hide a few things. I can't imagine that the owner is allowed to inspect your private locked furniture.
 
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