Looking for some opinions on internal overflow placement. I have been slowly piecing together my first tank and im at the point of drilling for my overflow my tank is a 40b and I have a lowpro 1000g overflow. I am trying to decide whether to mount it in the center or one of the sides of the back panel. I have came up with pros and cons both ways but I'm leaning to the center. what is you opinion and why?
There are a lot of variables to consider.
What sort of aquascape and flow pattern are you planning? Where the overflow weir entrance is located should be factored into your flow plan to allow for surface skimming with the weir. This is easier with an end overflow, since surface flow can be directed mainly from the opposite end toward the weir. Central overflows can cause dead spots on either side in corners where flow is more difficult to achieve.
How is your tank setup going to be laid out? Do you care if the overflow is visible in the case of an end overflow (or do you plan to cover it with something decorative), or would you rather keep the overflow hidden on the back? If you chose the back panel, it may be better to have a corner overflow to avoid flow issues mentioned above. A lot of reefs are built with central overflows, though, so it is probably mostly a matter of your opinion with your specific plan.
Does your stand have plenty of room for placing the plumbing down from the overflow at any location, or are there braces or supports preventing certain placements? Think about what you plan to have in your sump, the order of the sections in the sump, and access into and around the sump when placing the overflow drains.
Where do you plan to feed the fish? If you feed too close to the weir, food may get sucked directly in if you do not shut off the return pump every time you feed (which is probably recommended anyhow).
For my
90-gallon reef I am currently planning, the decision was made easier for two main reasons: An end overflow will make it easier to plumb into the mangrove lagoon beside the 90-gallon reef, and if I happen to crack the glass while drilling the plumbing holes the piece broken is much smaller and cheaper to replace. This setup does leave the overflows revealed on the ends, though, and I may eventually want to block them with a decorative trim panel. By having the overflow on the end, I can return from the sump on the opposite end of the reef and keep the main surface flow moving toward the overflow to avoid places where scum collects on the surface. Another reason I considered this position is to keep my options open in the future if I ever have the chance to make this tank a peninsula with 3 sides viewable. This probably is not a strong consideration for your 40B.
I asked a similar question for my reef that you might check out for more considerations from other members:
Weir Overflow Location
You may note that what is likely my final decision is not even one of the original options I included in the poll.
