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new tank holes


chimera

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and is "hansen" piping (or rather the adaptors on either side of the glass) the best to get?

also, is it possible to get a glass hole at 25mm re-drilled larger to 35mm? reason i ask is i will have a 35mm hole in the main tank overflow running to a refugium with a 25mm hole in the overflow, which then runs to a 3 foot tank with return pump. Obviously if the return pump in the 3 foot tank is pumping at the maximum flow rate of the 35mm hole in the main tank, the 25mm in the refugium wont be able to keep up. alternately, does anyone have links to sites that can calculate the maximum flow rate (in litres/hour) of a given a pipes diameter? (and perhaps an equation that takes into consideration the number of elbows in the system too?) if the flow rate of a 25mm hole is quick enough (and the piping between the refugium and sump is basically a 1.5m straight pipe, compared to a couple of bends in the main tank to refugium plumbing) for whatever the return pump is rated at, im sweet!

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All the plumbing here is in both (metric and imperial) so no biggie.

Whats the verdict? I am thinking of having just 1 bigger hole (40mm) to do the whole tank, as opposed to 2x 30 (or 35mm), but not sure yet. Can't seem to make my mind up!

Pieman

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Go bigger, i don't think the calculator takes into account noise. :wink: Too small pipe you get no noise but too little flow, "medium" pipe you get the flow rate you want, but sometimes with a lot of noise. Large pipe you get your desired flowrate plus no noise, and as reef said, the option to bump up the flow later.

Layton

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Layton - using Durso standpipes which are completely silent as the pipe is always full (no air through the pipes).

I suspect a single 35mm hole will be enough for the 8000 litres or so I want, but I might drill a second 35mm hole in case I need it (will glue and plug it).

So maybee just easier to have the 40mm hole, and put reducers back into the garage (or even at the taps under the tank). No the garage, then if I need more flow I don't need to re-plumb from the tank.

Hrmmm.

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I am running my 740 litre with 1 Eheim 1262 (3500 litres ish) and 1 Eheim 1050 (1200 litre an hr approx) and my 25mm hole working fine. I do have a 2nd 25mm hole at the other end, but its currently not in use.

All water is driven directly into my skimmer before entering the sump/refugium.

Pies

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I have just created an excel spreadsheet that calculates the maximum flow rate based on the height of the tank (less the height of the overflow from the bottom of the tank) and the diameter of the opening from the overflow. Based on a 600mm high tank with a 35mm overflow hole, 50mm up from the bottom of the tank (this accounts for the height above the overflow as well, doesnt take into account loss of flow via the standpipe) equates to a theoretical maximum flow rate of 11,340 litres per hour.

Interestingly, I also added an equation that works out how long it takes to drain a tank based on volume, water height and hole size. Assuming the overflow did not exist, it would take 10 minutes 52 seconds to drain my tank with a 25mm hole and 5 minutes 36 seconds to drain my tank with a 35mm hole!!! Just shows how much quicker another 10mm diameter is.

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Im taking into account what is stamped on the outside pipe. it states 25mm which i assume is the inside diameter of the pipe. as i say, it is theoretical and there are so many other factors that need to be taken into account. at least it gives an approximate figure to work with. if the 25mm stamped on the outside means a 19mm inside diameter, i would be absolutely stunned they would do that...

...and the above is assuming my calculation are correct - which i believe they are :)

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back on topic: just got the design changed so the holes are at the bottom now. I was looking at how i would plumb it up AND access the tank from the back (as its going in the wall). At the bottom will mean alot more room to work with. I have the bottom holes 150mm in from the back panel spaced as per the original diagram (except the last which is now 1100mm across)

Question: how far below the water line should the TOP holes at the back be drilled? they will all be 35mm holes. do you have the holes just above or just below the water line? I assume either just below OR just above with piping going under the water.

also, i just ordered a 3/4" sea swirl for the return.

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Chimera -

just got the design changed so the holes are at the bottom now

then...

Question: how far below the water line should the TOP holes at the back be drilled

I don't understand your question. If your drilling your holes through the bottom arn't they all going to be bellow the water line...

As per my previous comments and tank design pics, all the holes should be through the bottom, safer. Why are you still looking at drilling the back/side? Or are you just confused? Or am I confused?

Pie

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You are confused. There are holes in bottom AND top :) Question is about the top holes.

As per the original diagram, holes B, D and F (which are on the lower back) are moved to the bottom of the tank and holes A, C and E remain in about the same place. I currently have the top of holes A, C and E about 20mm below the water surface.

Is this about right?

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I am only confused because your explination is a bit confusing and I don't see why you are asking the question. You can put the holes anywhere you want, as long as they are bellow the surface of the water there will be no head pressure to contend with and the pumping loop remains closed.

The worst place to drill a hole is near the top of the back or front of the tank, as this is the place where the glass is under the most pressure and stress.

Why not put ALL the holes through the bottom of the tank? I can't see any advantage to putting them through the back of the glass, and it will be harder to hide them the higher they are drilled. Put em all through the bottom, and use pipe to direct the flow upwards. You can then use this pipe to support a reefrack and hold the rock in place.

Pies

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I am asking because I want to know where the most recommended place is for the holes at the top (ie: as high as possible, as low as possible, in the middle or whatever). i wanted flow for the closed loops from the bottom to the top and top to the bottom (or a mixture of both) to give good circulation and water flow (i will be using a reef rack too) i wanted holes just under the surface of the water (or as far to the top as practical) or considerably lower down and completely hidden from view (behind rocks) Much like this guys design:

111_1154.JPG

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