uncleof6
Active member
I'd like to first start off with props out to Bean, Uncle and the countless others here that have contributed their valuable knowledge and experience in educating us in new methods and techniques that have evolved this hobby to higher levels of satisfaction and enjoyment. My thanks to you all for your selflessness and tireless devotion to this art!
With that said, here is my design concept implementing a BA overflow utilizing an internal weir and external overflow box for an existing glass 100g tank (6' L x 23" H x 18" D). My required criteria were the following:
1) All permanently mounted equipment and plumbing must be housed entirely within the aquarium structure.
2) Maximize "dead space" utilization behind the tank around the drain and return plumbing.
3) Conceal all traces of overflow boxes, plumbing and equipment as much as possible.
4) Isolate vibrations from the external pump by using flexible tubing to connect it to all hard pipes.
5) Easy access and maintenance.
Once I decided on 1.5" drains throughout and 1" return split into 3/4" Loc-Lines, I had to determine the locations to drill the back glass. This required knowing the installed minimum heights and physical dimensions of each channel. I bought a 90 degree 1.5" elbow from a local Home Depot to give me some idea of the space the plumbing would need. As someone unfamiliar with working with this size, I was astounded at how large 1.5" PVC fittings and pipes are!
Hole placement also had to follow these golden rules as gleaned from this thread:
1) The center of the connecting holes between the internal weir and external overflow box needed to be at the normal operating water level of the overflow system, which appears to be approximately the center line of the open channel.
2) The edge of the holes must be at least one diameter away from glass edges and other holes (for the bottom glass of the external overflow, this was not possible due to it's narrow size).
3) The top of the weir should be at the bottom edge of the trim (or at least 1" from the top on rimless tanks).
I came to the realization that if I am to accurately plan a detailed construction list and layout, I would need to either purchase everything in advance and mock up a physical model via trial and error; turn to traditional paper, ruler, compass, protractor and pencil; or go the 21st century way via CAD. Although I have a lot of graphic design work under my belt, this is my first attempt at 3D design and there certainly has been a learning curve to hurdle over, and continue to hurdle through but I feel this has been an invaluable aid in accurately conceptualizing a significant and rather complex project of this magnitude; from construction and drilling of the tank and overflow system, sump, cabinetry cut list to critical placement and space management of all components. Despite some of its shortcomings, Google Sketchup has certainly been very useful, especially the ease to search and download public 3D models from the internet.
Suffice to say, the centerline of the 65mm holes (based on using the same hole saw used to drill the holes for 1.5" Schedule 80 bulkheads from Bulk Reef Supply) are 3-13/16" from the top of the tank.
I selected tinted glass (e.g. Graylite) for the weir and clear glass for the external box. A pair of glass covers over the weir (my tank has a 16" wide glass center brace which necessitates splitting the cover into two)
with 3/8" rubber "feet" keep most critters out of it. To match the thickness of the tank, 3/8" glass will be used.
I saw a potential for the large unused area underneath the external overflow to implement a gravity fed auto-top off system. By squeezing all the plumbing as far to one side as possible and accepting some of the compromises in this tight configuration, I am able to fit a custom 1/4" acrylic 31" L x 13-3/8" H x 6" D reservoir (roughly 10 gallons).
Although I have rendered the back glass of the tank clear to allow easy visualization of the various components, it will be painted black to hide everything from the front. To that end, I extended the weir box bottom to be as low as the external box's bottom in order to cover the entire perimeter of the external's silicone joints to the back (since those points can not be painted to hide it from the front), accepting that water below the connecting holes for such a deep weir may not have enough current to prevent crud accumulating in its bottom. Weir dimensions are 56" L x 7-7/8" H x 2" D while overflow box dimensions are 48" L x 7-3/8" H x 5-1/2" D. The shorter overflow is offset (aligned to left edge of weir, which is 2" from edge of tank) to allow filling of the top off tank. Top of overflow box is affixed 1-9/16" from top of tank (bottom should align with bottom of weir).
To enclose all the external plumbing and leveraging a custom built stand and canopy, I will have a pair of removable vertical opaque plastic panels on each side, notched on the leading edges to allow them to fit flush to the back of my rimmed tank. For illustration purposes, doors and back panels of the canopy and stand are not rendered.
The stand will be built deeper than the tank itself to incorporate everything behind it within it's footprint. As a benefit, this facilitates a direct, straight-down flow of the drain pipes into the sump. Average height figures helps provide scale as this is a rather large ensemble! Stand height to base of tank is 40" to allow ease of access and to fit all planned equipment inside. And by hanging the large reactors above the sump, any water leakage during consumable replenishment will drain into the sump.
I take no credit in the stand and canopy design. For that, my appreciation goes out to Will for sharing his magnificent 90g build. He has since left the hobby but I hope he returns to it again someday as he recently replied to a posting on his old build thread...
DISCLAIMER: I have never had nor maintained a saltwater tank before so I make no claims of knowing what the heck I'm doing! And before this endeavor, I've only had a couple Betta fish bowls. In fact, the only item I have on hand right now is just the tank.
Thank you for the kind words. This post really should be in its own thread, as there are many topics to look at here, aside from the drain system. It deserves to be in a build thread.
The big issue i see is with the pump intake. With your configuration, there is insufficient distance from the elbows to the intake. It lacks the straight length necessary for the turbulence caused in the elbows, to calm down before entering the pump volute. This can and does cause a pump to cavitate. The rule is 15 x the inside pipe diameter, however, often 7 - 10x the inner diameter can keep the pump from cavitating.
Also, i think you would be better served with a single return line, up and in , rather than up over up split dual in -- this will only decrease your pump performance, and you are not gaining anything by splitting the return at the tank. Also would upsize the return plumbing. 1" looks a bit small for that pump: assuming a 1" pump outlet.
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