Elevated fuge as a electronically-activatable surge tank

[Ebslinger]

I guess it comes down to risk vs reward. How much are you willing to risk, for the reward you will receive?

For me the risk is to high, even if the flow-rate of pipes would seem to support the idea. I just wouldn't do it.

If you do it, I want pics!

It sounds like an amazing experiment.

 

[burningbaal]

Because of a few of your thoughts here: I'm shifting my thinking away from the original uses with the solenoid-reg airline and the long downpipe.
I think this plan to just turn on a giant submersible pump to move water from the fuge into the fuge's overflow box (OB) is best.
Make the OB large (especially tall) with the siphon pulling off it's bottom, sure pipe somewhere a little above that, then the airline opening (violating BA, but I think it's ok because there's no worry about getting the main siphon started). Emergency is way up high, maybe above the OB weir
When the pump kicks on, the fuge OB rapidly fills, pushing the "open/surge" to siphon, rapidly dropping around 3000gph until the pump turns off (well, them a little delay until the siphon actually breaks).

The DT weir has to handle this extra 3000gph (planning around 900gph normally), but 4000gph isn't unheardd of for return rates, so I found be able to get a long enough weir it won't be a problem and the DT level shouldn't change much (well under an inch, I'm hoping) unless the overflow pipes fail, but having my 3" emergency pipe should resolve that worry, that size pipe should be able to carry double my expected flow rate even with the 900+3000, so even if both the siphon and the open fully clogged, the emergency should be able to carry it all.
Plus, all the water is coming through that 2" surge pipe (plus the normal flow), and the drop from fuge to DT is less that DT to sump, so the DT open should be able to carry more than the surge before the emergency even gets wet.

I _THINK_ it's foolproof

 

[burningbaal]

Also, any pump failure is all in the fuge, so no risk except heat. If the controller fails in a way that leaves the pump on, I'll probably need some kind of float to turn off the pump. Funny, I could use a jbj-style ATO brig to run the pump... Run when top is hit (and controller says surge is active), turn off when bottom drops (until top is hit again).
The real risk with this system is if the pump stays on too long, the pump will run dry and might burn up

 

[burningbaal]

ok, many thanks to you responders, I have another idea and I think this may be the best each.
The first idea wouldn't work because the BA siphon needs to be in the same body of water as the open/surge, second idea seems pretty tough to plumb right. Third idea has risk of the pump running dry (if it stayed on too long). But this one might do it (not drawn yet):

The beauty of this is the simplicity. take a pretty normal BA in a tall overflow in the fuge, add a U-tube with an aqualifter and solenoid (controlled), and you have what I want (I think). Now for the long story:

• do a normal BA in a normal overflow box in the fuge, but space the three pipes out vertically pretty far so there's lots of room for head pressure to push the siphon to start quickly.
  • I expect my fuge to be 25" tall, so:​
  • I'll probably put the siphon on the floor (literally, just the bulkhead, maybe a strainer if I feel like it), FWIW, I'm only going to run about 150gph through my fuge, so a 1/2" siphon pipe is overkill, but I'll probably use 1" with a gate valve shut most of the way​
  • open/surge a few inches up, probably just top it with a Tee and no airline kinda like an old-school durso. it'll start a siphon when the water level gets above the Tee, I'm planning 2", which should drain about 50gpm. you could put a valve on this to slow the surge, but...doesn't that defeat the purpose? If 3" parts are cheap, I might use them instead except I'm not sure my DT's weir will take it, nor the bubble tower in the DT.​
  • emergency around the 24" mark, way above the open/surge's top, preferably above the fuge's normal water level (could even put this outside the overflow box if you want, shouldn't make any difference at all)​
• get some very-large pvc (at least the same as the open/surge pipe) and make a big U ushape, just like would go on an HOB overflow...except:
  • Make it very tall (maybe 20") and a few inches across, draped over the fuge's overflow box wall.​
  • The side in the overflow box should go pretty far down, definitely down past the normal overflow's water level (when no surge is happening). the other side is up to you, but I plan to make the surge max out at about 50 gallons of water, so I'll probably have it go about 8" below the overflow weir.​
  • Put some thought into the height of the non-box side's length as the sump needs to be able to handle the max surge as 'extra'. Just in case the signals fail, you want to make sure the maximum surge volume (before the U-tube is dry on one side) is low enough the sump can hold it.​
  • put a fitting in the highest point of this U-tube to fit 1/4" airline, then an airline 'Tee'​
  • on one side of the Tee, put an aqualifter (make sure it's rated for more head height than the height of your tube, but it's probably not that important). Plug this into a controlled outlet, drain the output of the aqualifter into the normal fuge space, doesn't really matter where, but this seems best.​
  • On the other side of the Tee, put a little piece of airline with a controllable solenoid and make sure this airline runs pretty high, maybe just over the outer wall of the fuge, it shouldn't ever get wet. I suggest a 'normal-open' solenoid, which is opposite of most in the hobby. These open when they lose power and close when they have power. It's not a big deal, but in the inverse, a power outage could cause a surge to fully complete before the action stops, which seems a little weird, you'd rather have the surge stop when the power dies.​
  • Size the U-tube at least as large as the 'open/surge' of the BA so the BA is the rate-limiter, otherwise you could lose siphon on the surge pipe in the middle of the time you thought you were surging, so you'd get multiple partial surges and massive noise/bubbles. There's no harm in oversizing this u-tube, its job is to equalize the water level in and out of the box.​
  • Note: you might be able to replace the u-tube with a bulkhead in the overflow wall (in my case, around 8" below the overflow weir) with a controllable solenoid, but this isn't your normal airline solenoid, you've got to carry a lot of water through here, so you probably need a giant 2-3" solenoid (normally-closed this time). This seems more elegant, but a quick google search suggests this size solenoid runs several hundred dollars ​
• When you want normal 'fuge activity, open the solenoid and turn off the aqualifter.
  • It probably isn't important to turn off the aqualifter, but it isn't doing anything at this point, so you might as well turn it off if it's controlled.​
  • With the solenoid open, the siphon is definitely broken, so the fuge will fill until it goes over the weir (I'm planning 150gph, fill the whole fuge in 60 minutes), as the weir fills, the BA will do its normal job with the siphon pulling off the bottom (gated to take most of the 150gph, but not all of it), the 'open' taking a trickle. The emergency is dry. There will be some slurping as the siphon first starts, but shouldn't be too dramatic.​
• When you want a surge running, close the solenoid and turn on the aqualifter.
  • The U-tube will fill with water (from both sides) as the air is removed. It shouldn't take long to fill the tube if the fuge was in 'normal' mode because the water level is almost to the top of the U-tube anyways. As soon as this happens, a siphon is created and the U-tube will ensure the overflow box has the same water level as the rest of the fuge. The BA in the fuge will evacuate this water, so you'll get a VERY fast drain from the fuge, through the U-tube to the box, from the box through the BA into the DT. Best of all, it's all gravity, no timing anything, it just happens when you say so.​
  • I'm expecting the emergency to stay dry, if the emergency is below the normal fuge water level, that might not be true because the u-tube may equalize water level faster than the surge can flow. however, I'm planning on putting the emergency above the normal fuge water level (just below the lip of the tank), so it should stay dry even if the U-tube had no resistance to flow.​
  • I'm expecting the emergency is just for if the other two are too clogged to carry the 150gph coming from the return and in this case, I don't need it going into the DT, so I may send the emergency straight to the sump.​
  • As soon as the solenoid opens, the siphon will break and the overflow box will drain until it runs dry (presumably, no water will be entering the overflow box until the return has pumped enough to start going over the weir again, then the normal BA activity will resume).​
• With a controller running everything, you can go to siphon mode for, say...2 minutes (I'll have to dial in the number so the solenoid opens about the same time the u-tube siphon breaks), it will take a moment to start the u-tube siphon, then drain the 50g, then open the siphon again. If I want a regular surge, I can do it once every 20 minutes, or I can set it to once very 45 minutes, or every other hour, or once a day at 9pm (after last feeding), or just 'when I press this button'. I might have a small surge (30 seconds?) every hour during daylight and a large one before lights out, or something.

the big thing that's awesome about this is that it seems very unlikely to have bad failures.

• If the power goes out:
  • while in surge mode, the siphon should break (I plan to by a normal-open solenoid) and the box will run dry into the DT just as if the controller turned off the surge 'early', except the 150gph won't be flowing into the fuge, so this will happen slightly sooner, and the normal function won't restart until the power comes back on.​
  • while in normal mode, the fuge overflow box runs dry as the return's flow stops, just like a feed mode, or something.​
  • While in surge mode and the solenoid fails-closed: probably the surge will run until the U-tube hits air at its bottom), so I need to make sure the U-tube on the non-box side isn't so long that the sump can't take the water gain. I'm targeting about 50gallon surges, so it'll probably be about 8" below normal water level. I'll probably make it a threaded fitting so I can play with it.​
• If a pipe ever clogs in the fuge BA, I'll have a 3" drain dumping into the sump, that should have no issue carrying 150gph, even with a couple snails inside (which shouldn't happen, I'm just saying)
• If the u-tube ever clogs (unlikely with a large pipe), the surge just runs dry (in the fuge overflow box) faster than expected or can't even start because the water can't move from fuge-to-box as fast as box-to-DT, so NBD...I just don't have my nifty feature.
• If the DT pipe ever clogs, it will have its own 3" emergency drain to the sump which carries way more than the DT will ever receive, even with a 50gpm surge.
• if the surge pipe won't start a siphon (airline got moved?), the u-tube just fills the fuge's overflow until its solenoid opens. these two pipes shouldn't have any trouble moving the 150gph from the return, it doesn't really matter what the level in the overflow box is, there won't be enough water entering the fuge to flow into its emergency unless one of the pipes actually clogs (see above). I plan to put the emergency above the main fuge's normal water level, so it still stays dry in this failure condition.

Other fun bits:

• The surge start pretty fast (if starting from 'normal' mode). If you want a surge now, the aqualifter only has to fill a couple inches of pipe and the siphon should start, should be very fast.
• The surge can be however long you want, if you find the 1-minute/50-gallon surge is too much, you just set the controller to open the solenoid after 30 seconds, or 10 seconds, or whatever. remember the u-tube should only descend into the fuge side far enough that the sump can take the whole amount though...the sump is (eventually) where this volume is headed (until it gets pumped back up).
• The briefly-existing reef synergy ghost overflow (the 24" one) was rated at 4000gph, which is what my fastest rate into the DT should be (I'm expecting 900gph from the sump's return and 50gpm surge is 3000gph...momentarily). I'm planning a 4ft weir inside the tank, so it may be able to carry around 2x the fastest it'll ever see. The DT's external overflow box will be about 6" wide (2x the emergency's diameter), probably 24" long and maybe 8-12" tall, which means it'll hold the first 10% or so of the surge in the box (assuming it starts fairly empty) as the siphon gets started.
• I think it's best to set the DT's 'open' to be just like the fuge's surge pipe; with the airline ending below the emergency pipe. I realize BA has is reasons, but as long as the airline is pretty high above the siphon pipe, there should be plenty of head to get the siphon started before the airline gets wet. Also, my siphon pipe is going through the bottom of the box (bottom of fuge in fuge, bottom of box on DT), so 'getting the siphon going' isn't really about pushing water up, it's just defeating the venturi effect. Anyways, this way the open pipe in both should become siphons during the surge so it isn't quite so loud and I really want the emergency to only be used in an emergency.
• I think I'll build a little bubble tower like melev puts in his sumps, but in the corner of my DT and run the two drains from fuge to DT into this. poke a hole just above the DT's water line to help the siphon get going without an airlock, and push the fuge water (and pods) down near the bottom of the DT, probably put a false bottom on the bubble tower a few inches above the sand bed so I don't make a sandstorm every time. But I don't want the surge water (and pods) to just wash into the overflow and to the sump, so making most of the surge water go deep in the DT makes the whole tank surge up into the overflow (ish) and should help keep the pods in the DT.
• Sending the surge into the bottom of the tank makes for a bubble nightmare, hence the bubble tower, that should keep the air bubbles mostly out of the DT and the rubble should make for an extra little pod hotel in the DT. I just need to make sure the bubble tower can pass 3000gph through it... :/ A quick calculation says a 12 sq in submerged rectangle will pass over 50gpm with a 1" height difference, so I might shoot for 20 sq in of holes in the bubble tower...I might actually make the bottom couple inches of the bubble tower out of egg crate. If the bubble tower is 4" x 4", a 2" egg crate at the bottom is 16 sq in, so I'll probably do 3" at the bottom of the tower in egg crate. I'll make the bubble tower out of 1/4" black acrylic. I don't want to see the rubble, and there's virtually no pressure on this (bottom is open) except the 1" of head height, so a weak acrylic-to-glass bond shouldn't be a problem, my 29g is doing this right now with 1/4" black acrylic and a 5" baffle is held only with silicone (to a glass tank on one side, to more acrylic on the other). Also: worst case if the acrylic-glass bond fails is some rubble in the DT and lots of bubbles during surge
• The normal 150gph fuge rate will be draining into the bubble tower as well, so I expect the fish that like snacking on pods might hang out by that egg crate
• I might put a 'boring' powerhead in the fuge to stir it up (loosen detritus and pods from the macro), I might just do that by hand occassionally. I think I'll put some egg crate up as a wall so the macro can't be right up against the U-tube and cause issues, and I'll set the return line so it pushes into the macro from the U-tube's side of the egg crate with small enough nozzles it pushes the macro away from the egg crate for good recirculation...that's the idea...I may just have the return push toward the egg crate, we'll see what gets better growth.
• I plan to only put lights on the macro-side of the egg crate, hopefully there won't be much nuisance algae on the plumbing side...but I may need to add some light-blocking to address that.

Oh, and I'm leaning toward caulerpa...we'll see.

So...bad idea? is this better? can it get even better? Will it work at all?

 

[burningbaal]

Oh: perk of the weir is that we are surface skimming off the fuge during normal mode. Ideally, we probably send this surface stuff to the sump (skimmer), but to do that, I think you need a separate overflow box in the fuge so the only time water goes into the "main" one is during surge, but then you never get any fuge water into the DT except b during a surge, which is no fun.

Maybe there's a way to fine tune the heights of the twin overflow boxes so a trickle guess to the sump, but that's too complicated. The DT will have a monstrous long wier to handle the surge without a big DT water level change, so when not surging, it'll be VERY efficient at skimming the surface, whatever oils go from the fuge to the DT will end up in the DT surface and immediately whisked down to the sump.

 

[burningbaal]

extra bonus: the surface of the fuge is skimmed even if the surge is nearly-always going...for a short bit right before the u-tube siphon starts, the surface is pouring over into the fuge's overflow box and into the BA.

I think, with the surge pipe being 2", there may be no point in my siphon from the fuge. while in normal mode, there's only 150gph going into the fuge, and the 2" open pipe should be able to handle that without any noise. when the surge starts, the open pipe gets drowned, so it goes to a siphon and pulls however fast it can (there's still only 150gph being added to the fuge, the u-tube is just equalizing the levels). when the u-tube siphon breaks, the surge pipe will finish draining the overflow box and switch back to 'open' mode.

This makes the plumbing simpler (one less pipe/bulkhead to assemble), it removes the need to tune the overflow siphon pipe, it frees up space in the DT's bubble tower. The only limitation is if I want to increase the fuge's return rate (above the 150gph), I'd run up against the silent flow capacity of the open pipe (and can't open up the siphon to gain capacity). But if the silent open flow rate of the 2" pipe is high enough, I'd have plenty of flexibility. I'm betting I could go 3x or even 5x the fuge volume per hour silently in just an open pipe (basically a durso). I'd still do the giant emergency because...clogs.

I think I'd keep this simple though, with only 150gph normally, I'm betting a boring spa inlet strainer will pass the normal return rate silently, and minimize the vortex when it goes to a surge (siphon). The main noise in this plan would be the 150gph falling over the very-tall weir in the fuge, so I may need some solution there.

 

[burningbaal]

Ok, a couple new shots. The idea is to put a giant pool drain in the fuge with a 2" pipe to the DT. No need for BA's siphon since the 150gph non-surge should quietly trickle through here to the DT. emergency is up high and just goes straight to the sump. I've drawn it with a 4" acrylic box that climbs over the fuge's overflow wall. Note the other large wall in the fuge is some kind of TBD divider to keep the macro out of the way.

Notice the aqualifter and solenoid on top of the acrylic box. both are important, and assuming the solenoid is 'normally-open', both should either be powered, or not-powered in unison. Both Tee off a 1/4" airline fitting that goes into the top of the acrylic box.

the gravel is the best I could come up with, but just imagine it's a normal pool grate, maybe 8"x8" or so, covering a 2" bulkhead.
Notice there are 4 notches (one per side) in the drain-side of the acrylic, I drew them each 2x2", so I'd have 16" of drain space, plus the 16" going straight down into the drain...should be overkill, but no-restriction is the idea, and we want the siphon to break cleanly when it breaks.

On the fuge-side, I have much taller notches (I probably only need one or two since' they're so large), these will break the siphon when the fuge level drops 8" from the overflow weir,which should equate to a max of 50g surge.

Big note: This IS NOT like a carlson or borneman surge device, it DOES NOT just run on its own, a controller needs to run it. In theory, you could just leave it in surge, and the 150gph would fill until the aqualifter started sucking toward a siphon again, but it would end up with less than a 50g surge after the first time, and it would be way noisier. This is probably only remotely quiet/bubble-less when it is engaged while the overflow is near the top of the weir. So I'll use it with a controller to kick on and off. probably turn on for about 90 seconds (get the box siphoning and then let it drain for 60ish seconds) before breaking the siphon and letting the 150gph return fill up again. perhaps every 20 minutes I can do it again, I probably wouldn't program more often than 30 minutes, and really, probably only a few times per day plus manually.


So: Thoughts?

 

[skyrne_isk]

OK, more detail. I added a draft of the sump here. note the fuge's emergency just drains to the sump, no sense it making the DT deal with whatever emergency is going on. I didn't show the DT's bean animal all the way down, but I think we're all smart enough to show them going down to the sump. also, I think the fuge will actually be above the sump, just about perfectly stacked, not turned 90 as shown, but this makes the plumbing easier to see.

It also shows the valves on the return. I expect I'd have the return to the display tuned so about 150gph goes through the fuge (I'm assuming the water wants to go to the DT since it's lower, and I only tune down the DT's valve). The valve going to the fuge is just to shut it off when needed for maintenance/etc.

Sump shows a little 2'x2' box with a little under-over-under to make sure whatever is happening in the rest of the stock tank sump, the return is getting bubble-free water. Basically, I build a nice little box, taller than the water level I want, with one end built out with this baffle setup. Put the return pump in the box with the ATO. I'll probably put another optical sensor in there with a PMUP as well to do a few gallon's water change every day or so...volume and frequency of that AWC is TBD.

Should be room to stick sensors in the main sump area, along with the skimmer and some other things (reactors, etc). The DT will have a 1 or 1.5" gated siphon, a 2" open, and a 3" emergency draining to the sump, plus the 3" emergency from the fuge. the DT will have the 1" gated siphon and 2" surge-type open draining from the fuge.

Does the plumbing work? Does this thing just turn on whenever I close that solenoid? how careful does the open/surge pipe's height need to be?

I am not quite following the plumbing of the surge drain. I am with you that the solenoid needs to be normally closed and only open when you want to surge the tank. but if you imagine that a quarter inch solenoid is going to be able to make all of that work I don’t think so. I would go with the biggest solenoid you can reasonably put in like a 2 inch or 3 inch variety and then plummet in below your drain and I think you’ll be OK. Also if you are running a true bean style overflow you probably don’t need to run your water level lower in your name display. Unless you are searching a huge amount of water - the bean animal drain should simply pick up the extra volume and the trickle drain but other than that you should be OK

 

[skyrne_isk]

what would be amazing is to
figure out how to control this over WXM with your Apex....

 

[burningbaal]

what would be amazing is to
figure out how to control this over WXM with your Apex....

The idea is more thoroughly described post 24, then pictures in 27. Though I think I've decided the acrilic box u-tube will just make the siphon hard to start, so I'll probably use a 2 or 3 inch regular pvc instead.
But the idea is to have a solenoid just to break the siphon in the u tube. So the aqualifter pulls a siphon, just like a hob overflow.
Then a big 2 inch drain dumps the fuge overflow in to the DT.

And yes, the DT will have a bean animal, though I think I want to oversize the open to 2 inch, have it's airline just below the emergency, and have a giant 3 inch (impossible to clog) emergency. I expect it will carry the 50gpm surge in the open (that becomes a siphon).
That said, the trick regarding water level of the DT is probably dependent on the weir capacity. The water level will definitely be higher during a surge, but I'm hoping it's only a fraction of an inch

 

[burningbaal]

Meh...this needs tuning. the overflow side of the u-tube needs to be underwater and I think the u-tube needs to be smaller so the aqualifter can really start a siphon...but the premise is (hopefully) visible.
I think I'll adjust it to raise the drain a few inches so there's always a few inches of water in the overflow, so the u-tube is always submerged on the overflow side. might drop the pool filter and just use a regular guard over the 2" pipe; the 150gph fills the bottom few inches until it trickles into the 2" pipe, and when the u-tube goes to siphon (surge), it quickly swamps the 2" pipe which surges into the DT.

I'll see if I can draw it up better, not sure when I'l lget a chance

 

[burningbaal]

OK, trying again. I realized the overflow's drain can't just be a floor drain; it needs to hold a little water so the aqualifter can start the siphon in the u-tube. I also decided the giant acrylic box for the u-tube was not only overkill, but would be very hard to start the siphon, so I've gone to 2" plumbing just like the drain to the DT.

The idea is to have a drain that comes up into the overflow a few inches so the u-tube is always under water on the overflow side. this u-tube has a couple Tees on the fuge side so I can try different surge sizes. If I leave the screw-plug out of any of those Tees, the siphon will break early and give me smaller surges (regardless of the aqualifter/siphon setting/programming, which could make smaller surges based on timing).

I think I'll make the drain to the DT come up and back down so it's pulling water off the bottom (keep the bottom of the overflow a little cleaner), I'll poke a small hole in its top so it doesn't siphon the overflow box until that hole gets drowned by the U-tube's inflow.

Again, with a normally-open solenoid on the u-tube, the u-tube will fail to NOT siphon (aka: not surge) during a power outage. If you put the aqualifter and the solenoid on the same outlet of a controller, the siphon will start building when it gets power ('surge on') because the solenoid doesn't let it vent, and the aqualifter pulls a siphon into the u-tube just like a normal HOB overflow. when that siphon is made, the fuge will quickly drain into the overflow until either the outlet loses power (solenoid opens/aqualifter off) or the fuge level drops below the u-tube opening (I plan to make this about 8" down). as the water rushes into the overflow, the drain to the DT pulls a siphon as it gets drowned, and it drains about 50 gallons per MINUTE into the DT.

the display tank will receive the 2" drain from fuge into a 4x4 bubble tower to minimize bubbles. I'm thinking 6-8 cutouts in the bubble tower, 1/4"x3" should let most of the surge's (and fuge's) water out near the bottom of the tank (helping get good turnover of the water) but with minimal bubbles. Anything that can't surge through those cutouts can flow over the top. Yes, I'll poke a hole in the drain from the fuge at the DT water level to ease the starting of the siphon. I plan to put the bubble tower top level with the DT's weir so any water pouring over the top doesn't have to fall into the display

The DT weir will be about 68" long, I think I'll try for about 1/4" teeth with 1/4" between the teeth, so a small fish or snail might get through, but most shouldn't. I want them about an inch tall, which slightly lowers the water level, but gives some safety with the surge capacity, that gives about 34 sq in of open weir space, and the 2" drain from the fuge is only about 3" of drain, so I should have plenty of weir capacity. This then drains through a 20" wide opening in the back wall to get everything to the external overflow, probably 1-2" tall, so again: plenty of surge capacity.

The 1-1.5" siphon of the DT's BA should carry most of the return's 900gph, leaving the 2" open and 3" emergency to carry the surge (though I hope the emergency will stay dry). large open is to accommodate the surge and minimize risk of clogs. 3" emergency is purely to avoid clogs. the siphon will drain to the skimmer section (the highest of the sump), the open will drain to the main area, the emergency will drain straight to the return section so it's more obvious when it's in use.

Thanks to all who've helped discuss this with me, I appreciate it. It really is helping shape the idea and fix the problems. FWIW, I can't actually do this until next year (I'm still just rolling with my new 29g while I plan the 6' tank)

 

[burningbaal]

FWIW, I'm building out some of the description of the whole system here, it may make for a more clear picture of what I'm targetting

My Dream Reef Build

I'm Keith and I live on the northern side of the Seattle Metro area (Washington, USA). I have had a...

burningbaal.tumblr.com

 

[burningbaal]

huh...I just discovered an interesting thing here. My plan is to have two 150g stock tanks in the fish room (right behind the display), the bottom one as a sump and the top one as the fuge/surge. I've now realized that the bottom of the fuge will actually be below the top of the display tank. No big deal, the surge will still happen, though it could be slower since there's not much head pressure.

What was interesting: I was kinda irritated that I have to go out the bottom of the fuge, around its stand and up a ways, then down into the bubble tower. Then I realized I could go up through the bottom. If I have a bulkhead in the back-left of the display tank (in the black-acrylic bubble tower), I can just plumb the pipe straight from the bottom of the fuge to the bottom of the DT. "weird", I think...The pipe will always be wet as it will just be equalizing the water level in the DT with the water level in the fuge's overflow box. "OH!", I think: that means the pipe is guaranteed to always be in siphon! If I set the u-tube's length in the overflow box so it ends below the display's water level, the siphon will start perfectly. yes, something that gets into the bubble tower could crawl against the 150gph flow into the fuge's overflow box...no big deal and it'll get washed back into the bubble tower when the surge happens Plus, if the pipe gets clogged, the surge just doesn't go very fast, not an issue. and a 2" pipe probably won't get clogged.

Here's the thing: now the pipe will always be siphoning...it will never break nor start a siphon (unless the DT water level drops dramatically below the weir). So the only noise that can happen is the u-tube starting/breaking the siphon and the same goes for bubbles in the display.

Thoughts?

 

[NautiTang]

Finished reading through this finally, with some stretching of the brain muscle, the last couple posts with the sketches made comprehension easier. You could put some foam pad or a mesh of some type to keep the critters out of the bubble box. Or since you will have a constant siphon get rid of the bubble box right?
Very interested in seeing how this goes.