sleepydoc
Team RC
Posted that just recently in this thread I believe, prior to yesterday...
Damned Alzheimers! :hmm3:
Silent and Failsafe Overflow System
- Thread starter JohnL
- Start date
Damned Alzheimers! :hmm3:
uncleof6
Active member
What I posted, but it is still your alzheimer's because the hole placement has been posted a hundred times.
Nothing I'm looking into is working out, so I'm going to be going with a standard overflow box peninsula style on a 180. The question I have is how large to make the drains? 1", 1.5", or larger? I'm not sure which pump I'm going to use for a return, just want to make sure I don't go too small for the drains. I realize that I won't be getting the major benefit of the surface skimming this way, but since the tank is going upstairs I want to be safe. Has anyone done an internal overflow without teeth to get better surface skimming?
uncleof6
Active member
Probably thousands have done an internal without teeth. Calfo's C2C has been around for a long time. I have done a couple three hundred, if I have done one.
Since you have not made the decisions you need to make, before building this thing, you are getting way ahead of yourself. You need to pick a flow rate, 10x, 100x, XXx... you need the length of the drop, to figure out the drain sizes, you need a return plumbing configuration to do the friction loss calcs at that flow rate, to figure out what pumps you can and can't use. You should not think about buying anything or cutting any holes, before the paperwork is done.
Thanks uncle. The stand will be about 40" tall and the sump will have the drain-section's waterline at 15", so the fall will be 25" + the height of the BA standpipes inside the overflow + 1" depth into the water. I plan for the drain pipes to be vertical with no elbows and make a straight shot to the sump.
uncleof6
Active member
@ 5x 1" bulkheads are fine. @ 1800gph + (where it should be and to do this system justice) 1.5" bulkheads. It appears that you are aware of the surface skimming/renewal efficiency you are sacrificing in doing a peninsula type tank, opposed to a traditional setup, e.g. short weir to flow rate, and the distance being ~6' rather than ~2' you need to pull from. That needs to be taken into consideration when setting up your power head circulation scheme.
Thanks Uncle. The plan for me going peninsula is to create a circular pattern of water flow wherein the returns force water down the overflow wall, then maybe pumps on either side of the overflow down low to push the returned water toward the opposite side where the gyre (or MP, etc.) is positioned up high to push the water back toward to overflow while disturbing the surface all the way back to a 'toothless' weir/overflow. I'm hoping that this eliminates as many dead spots as possible. My next question is how thin a sheet of water I can get over the smaller trapezoid-shaped weir while getting 1800 gph through the sump?
uncleof6
Active member
Well 1800gph wants to see ~27" worth of weir, minimum, so it really depends on how wide your tank is. I assume that a 180 is ~24" wide, and that is close. I have recently gone looking into some dimensions, and I am seeing a lot of funky dimensioned tanks, that don't lend themselves very well to marine system. Those being taller than they are wide.
Weir calcs I don't like to do very much, the information can be garnered on the internet, and will be fairly accurate as to how thick the layer of water over the weir is going to be, using the Francis formula, you rearrange the equation to solve for h, the head on the weir.
http://www.engineeringtoolbox.com/weirs-flow-rate-d_592.html
That said, you want the thinnest layer possible. On the end of the tank, that will be the full width of the tank, regardless of flow rate, it won't get any better than that.
I also withdraw my comments concerning the gyre, and hang my head in shame. I had seen those before, but the name wasn't clicking in my head. Does exactly what I was talking about.
Weir calcs I don't like to do very much, the information can be garnered on the internet, and will be fairly accurate as to how thick the layer of water over the weir is going to be, using the Francis formula, you rearrange the equation to solve for h, the head on the weir.
http://www.engineeringtoolbox.com/weirs-flow-rate-d_592.html
That said, you want the thinnest layer possible. On the end of the tank, that will be the full width of the tank, regardless of flow rate, it won't get any better than that.
I also withdraw my comments concerning the gyre, and hang my head in shame. I had seen those before, but the name wasn't clicking in my head. Does exactly what I was talking about.
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Thank you, and no worries about the gyre - just threw me off track for a bit. I will look into the Francis formula and see what I come up with.
The tank is planned as standard 72x24x24. Is there a benefit from dropping the height to 22" or 20"?
For the overflow, will I get any benefit by having the trapezoid shape? I'm guessing 6"-8" per side and 15"-16" across the front. That will give me 27" - 32" of total weir.
uncleof6
Active member
There is, but 24 x 24 is fine. The classic examples are the 120 and 180, (24 x 24) being the quintessential marine tanks. My 300s are 72 x 36 x 30. (Actually around 325.) The 8' 240 is some folks dream tank, but a 5' 240 is a better tank, that one could be chalked up to an opinion I suppose, as the 8' has more surface area, by 144in².
Starting at the 55 and going up through the sizes ending in 5 are more for freshwater systems, and are not well suited for marine systems. That is not an opinion, rather is based on the surface area to volume ratio, in terms of gas exchange.
The ends of the weir count, if it is a 3 sided type arrangement, or trapezoid configuration. It will get dicey the closer the weir comes to the glass, and water starts splashing off. Just don't short change your self in the plumbing room, 16" is pretty small. I think an L shaped shelf 24" wide will do the job, though a 72" weir would be much better...
Joe the painter
New member
hi everyone I am setting up a brand new 210 and i am new. I just drilled my holes for 1.5 bulkheads 4 inches from the top of the black trim to the top of the hole. i know i screwed up,but its too late. will the ba still work? if not is there anything i can do to correct the problem?
uncleof6
Active member
Of course it will work, you will just have a higher waterfall into the overflow, which may make some noise, and the box will have to be taller.
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