My "goal flow rate" is 10-15 times turn over of the display tank. 210g tank... minus sand and rock.... 3" of sand... 250lbs of live rock. Not so sure how to estimate the lost water volume of 250lbs of live rock.... so I am estimating that if I target 2000gph, I'll be in the 10-15 times turnover range.
I absolutely do NOT want ANY risk of overflow or flooding. I "feel" like at a 1.5" Beananimal I am covered well and fault tolerant.... but I wanted to check.
I've got a separate thread asking for feedback on the right return pump.... I am thinking Jebao 12000 to get me the 2000gph at 4-5 ft head. Even that's an estimate.... because of elbows in the pipes and such causing increased resistance.... I'd rather "oversize the pump" and dial it back... and the Jebao 12000 seems on the boarder of being able to do it.
Feedback appreciated. Thanks
Mark
Well, the high pressure (or back pressure or whathave you ... to not get into semantics) isn't at the top of the pipe, it is at the outlet of the pipe. At rest, the pressure at the top of the pipe will be lower than the pressure at the outlet. Yes? Atmospheric pressure vs the hydrostatic pressure at the pipe outlet. Yes? Remember, the pipe is submerged so you have atmospheric pressure + hydrostatic pressure due to gravity exerted on the fluid. Most often atmospheric pressure is zeroed out (gauge vs true pressure.) When running the same relationship exists. Low pressure at the top, high pressure at the bottom. Yes? So there needs to be a way to overcome this, or nothing happens. What? Water flowing from low pressure to high pressure?
What is needed is head pressure (head height whatever) above the point where the water starts to head down, whether that is inside a tee, a double 90, or an open pipe. Without it, the system will stay at rest till the end of time. Even though there is a point where gravity and the surface tension of water take over the bulk of the work, a certain amount of "head pressure" is required to maintain the running state, or the system will return to a rest state.
The low pressure is easily observed. It is shown by the vortex that forms if there is not enough head height above the inlet to the siphon. The high pressure at the outlet is easily observed by noting how hard (or how easily) it is for the system to get going.
We are not talking huge differences. However, the deeper the outlet is, the higher the pressure, and the harder the setup needs to work to get going. (More head height is needed.) And yes, if the outlets are too deep in the sump, and there is not enough head height to overcome it, the system will fail to start, it simply does not matter what the upper topology of the system is. Whether that notion is liked or not, it is precisely what is going on. Ells where used in the model, and all of the systems I put up (~200+) and the reason for the ells is to reduce the height of the water column needed to maintain the system in a running state without sucking in air. I am not going to get into a debate regarding the relative merits of top end topology, all things equal the difference is not significant enough to really be concerned with, other than water height requried to maintain the siphon.
There is a great difference between draining water, and this system working the way it should. Watching you-tube videos is a double edged sword. How does one know if what one is watching is actually working right or not... videos are not a good source of information, generally they are more self-serving than anything else. That begs the question how would I know...
Over the years, and dealing with hundreds of "issues" posted here, a very short list was seen of possible things that could go wrong. All of them flaws in the implementation; a failure to follow the simple instructions, is what it really boils down too. Engineers love to fix things till they break; DIYers love to tinker with stuff, it is almost an obsession; Person A needs to outdue Person B; Person C needs to outdue both A and B. Persons D and E don't have minute 1 in experience, but they have something to say, that is only repeating what Person F and G said... Toss in some cognitive dissonance by as you put it "armchair scientists" (I don't own an armchair... seems i missing out...) and you have hundreds of posts going over the same material time and time again, (e.g. we have a big mess) that has only one possible conclusion: It works as designed. It is demonstrable, and repetitive (probably in the thousands of systems now) There is one set of circumstances in which the system works properly. There is tolerance in the system, by design, (it is not a rocket) however if modifications move the system out of the "neat little package of circumstances" it will probably drain water, but it can hardly be said to be working properly. (restart failure is a good clue... and that is 100% an implementation flaw.) Rather than fix the problem, or admit that the modification was not such a good idea, the hunt for a work around begins... well here we are 10 years later, still going over the very basics of how the system is supposed to work, and why it doesn't... but what really puts the cap on it is "Xgph without issue," really, need to get a flow meter involved, because the pump (despite the idealized flow curve) isn't even capable of doing that given the installation... (not speaking of anyone, or any pump, in particular):wave:
I can't find fault in trying to minimize the form. However, there is a point where it just goes too far. And we are at that point. (past it most likely) We lose sight of other important aspects of the system overall (even if the drain system works perfectly.) Aspects that we spent "years discovering," that are practically completely ignored/dismissesd out of hand. (aspects outside the scope of a thread concerning a simple drain system.)
Got a problem getting the system to work? Is it sluggish and/noisy? Just doesn't seem to be right?? Ask sleepydoc, his keyboard does not have a mind of its own like mine does... :bounce2:
Keep in mind that the '10x' flow rate that gets thrown around is for total flow - it doesn't all have to be going through the sump; power heads can add to it as well.
The sump flow needs to be adequate to keep the water well-circulated so skimmers and other filtration equipment can work well, heaters/chillers can properly regulate water temperature, and surface skimming by the weir is adequate.
On top of that, the amount of flow necessary also depends on the type of tank - a FOWLR tank needs less flow, a tank full of SPS will need more.
Yeah, I know that.... I've found that "more" is better in some things. More water volume in the system for a fixed bio-load is always good.... and I've found more flow is darn near always good.... as long as it's not extreme. Rock obstructions... all kinds of things obstruct flow... so I always oversize a bit.
I am also a bit worried on my skimmer set up. I have a display tank (210g), refugium (120g), and sump (40g). The way it's plumbed, the refugium and the DT return to the sump.... but I have the skimmer in the refugium. Therefore, proteins and crap from the DT need to go into the sump... and get pumped from the sump into the refugium in order for the protein skimmer to "get them". Having the protein skimmer in the sump just doesn't fit. I know that's not optimal.
I'll have filter socks on the returns in the sump. Changing those regularly and keeping them clean will be key. I think this'll work. I had a similar set up with a 120g DT, 55g refugium and 40g sump and it worked great.
Bottom line is that I want high flow in the DT.... turn over and power heads..... keeping that water moving and getting it into the refugium and skimmer as many times an hour as possible is important.... because in this set up, I am recirculating "dirty" water from the sump back into the DT that hasn't passed through the refugium and skimmer at any moment.
I couldn't figure out any effective solution to link the three tanks otherwise though....
Mark
Found this thread....
http://www.reefcentral.com/forums/showthread.php?t=1814606
It indicates that a 1.5" SCH40 PVC at full siphon should handle 1719gph at 4ft drop... if I am reading that right. It also indicates to derate that 15%... so 1461gph.
M
It will handle a lot more then 2000gph I would imagine.Found this thread....
http://www.reefcentral.com/forums/showthread.php?t=1814606
It indicates that a 1.5" SCH40 PVC at full siphon should handle 1719gph at 4ft drop... if I am reading that right. It also indicates to derate that 15%... so 1461gph.
I am building a 1.5" BeanAnimal.... the question is how much flow can it handle safely??
1461gph seems low compared to other things I've read. If you assume the Emergency's function is to replace the Full Siphon in case it blocks... I'd allocate 0 gph to it. The Open Channel should be at 50% max I'd guess. The question is what's the max for an Open channel 1.5" PVC at 4 ft drop???
I am guessing here.... but I am doubting it'd get to full siphon and not be sucking air since it is relatively high.... if full siphon is 1461gph..... let's guess the max is 1000gph. 50% of that is 500gph....
Thus, a 1.5" Beananimal should handle roughly 2000gph and still be able to accommodate a clogged full siphon without overflowing.
Is that right??
M
Problem is that the thickness if the acrylic us only 4mm.those teeth actually do look really tall. You might be OK with that. Worst case scenario, you could bust out a few teeth if the flow was too much...
Problem is that the thickness if the acrylic us only 4mm.
Sent from my GT-N7100 using Tapatalk
I think you are right in that there could be a depth of the tube in the sump that would simply prevent the siphon from starting. Changing the top-end topology won't eliminate this problem entirely, but I do find that not having the tension of that air bubble up top, greatly reduces the risk of it not starting, regardless of how deep that tube is (like, it might add enough pressure that even 5" under water is fine, by simply not having those 90s, don't quote me on that, i'm just using it as a "what if" scenario.) Now i'm not saying it'll work if you plumbed it to the bottom of your sump, I'm just saying that it seems to increase the safety margin by a fairly large amount.
On the other hand, I just spent today adjusting and tuning my 60 cube's herbie setup after watching my video again and thinking over some of your comments regarding how these systems are supposed to start up, and you were totally right, too, it wasn't starting up correctly, as it kept using the trickle/open channel far too much, and it wasn't putting enough pressure on the siphon line to get the siphon moving, at least, not all the time.
Mind you, this does have the double 90s, and i never had this issue on my 120G which doesn't have those. However, a simple strainer on this tank is likely not going to suffice, as it requires setting the level in the weir pretty low to do that without venturi, which is really noisy in that internal overflow box (waterfall effect) and in an external overflow box, the weir isn't nearly as deep, so water-falling water wasn't a problem, but it's looking like i'm gonna need the double 90s to keep things silent in the 60 cube. Ultimately, I raised the durso's height, and I did cut down the tube in the sump as well so it's about 1/2" below the water in the sock chamber, and this did solve the problem. Although now with the siphon fully closed, my water level gets pretty high, like half inch from the top of the rim. I think I'm OK with 1/2" given that the durso is actually handling the full flowrate of the pump with the siphon fully closed, and other than being loud, it functions fine that way. Oh yeah, and I finally cut that 12' of return tubing down...and there is definitely way more flow now, probably went from being 1/2 up the teeth to like 3/4 instead. Still not maxing it out though believe it or not, but it's getting closer to being able to the more i optimize the flow rate on this thing. I suspect if i up it to 1" all the way, I might be cutting it a little close, though. Pretty much tempted to stay with 3/4 just to purposely reduce my pumps flow rate into "Safe" margins for this tank's plumbing.
LOL I also found a paper towel I left shoved into my union to prevent glue dripping out....still in the union, somewhat attached to the pipe LOL. ooops! Cleaned all that up, lol. So yeah, in my last video of that system running, there was totally a paper towel blocking most of the siphon drain line and it was still flowing fine. Heh, unintended blockage test?
Haha, truth be told, it's the internet, so to some extent, it's to be expected that people will just post questions that have already been asked and answered 1000 times....and just not do the research ahead of time, lol. This might be an amusing read, if you've never seen it, "how to ask questions the smart way"
http://www.catb.org/esr/faqs/smart-questions.html
if only everyone did that right? lol
i've always been a "KISS / keep it simple" kind of guy, not just with fish stuff but with programming and electronics as well, occam's razor is another good one, lol. if there are parts that can be simplified without reducing the safety margins then i'm all for it, but knowing where things can be simplified is the hard part,on my 120G, using that strainer works great in the external box, but on the internal weir in my 60 cube, it's now clear a strainer may not work. If you'd asked me a week ago, I'd say strainer all the way, but it's clearly not going to work in every scenario, this is where experience can come in, and knowing just how the system is supposed to run is very important in that circumstance.
Well, to be frank with you, your herbie is not set up correctly, nor is it really safe.
Credit to Herbie for publishing before most of using siphon system prior to his "article" even thought about putting it on the internet, and in fact this sort of drain predates the internet. He modified an existing system, to fit in a small corner overflow (form vs function.) Essentially removing the Ells, and putting it in a corner overflow. Who knows who came up with the original system idea first, could have been one person, or a hundred simultaneaously.
Siphon systems are a risky proposition. Richard Durso's standpipe was a direct response to the inherent risk of a siphon. As we all know, the Durso goes nuts if one tries to put the spurs to their system. Which left those with large tanks and high flow rates, out in the cold with the risk of a drain that did not allow air in capable of flow rates measured in thousands of gallons per hour. Long story short, it only takes once, to learn that it is "extremely unwise" to run a "siphon" system, without a dry emergency backup; repeat: A DRY EMERGENCY backup.
The definition of a "dry emergency" is a pipe that is dry, e.g. it doesn't have any water in it, in point of fact the inlet is above the steady state water level. It is extremely improbable that a dry pipe will become plugged up, occluded, have junk grow in it, or otherwise fail. There is simply not a failure mode for a dry pipe. Nothing will get sucked into it, and sea critters, as curious as they seem to be a times, won't stray too far from water. (Jumping fish and such is a different topic, and relates to poor husbandry)
A wet pipe is a plug risk. There is no way that it could not be. A little water, a lot of water, it is a risk. We can banter on and on about the statistical probabilities, but a small risk is still a risk, and the cost of damage simply is not worth the risk. Bean has had two wet pipes plug, I have had two wet pipes plug, and I am certain that we are not the only ones.
Herbie knew the "law" for running a "siphon" system, and was adamant that one MUST use a dry emergency with his modification, or they would be begging for a flood. (adding to that: or at the least a burned up pump.) The notion of using a "durso" or "open channel" did not occur till several years later, after Bean published his system. Bean is a pretty sharp fella too, and he knew the "law:" never run a siphon without a dry emergency. He was adamant about it, and failing to do so is asking for a flood or burned up pump. His words: "All three pipes must be used."
The forum "telephone syndrome" grabbed ahold of these systems, and went beyond extreme when the open channel was attributed to the Herbie, and the dry emergency attributed to the Bean. The facts are exactly the opposite. (the dry emergency predating both systems.)
So you are not running a Herbie, regardless of what many would like to call it. A Herbie has a siphon and a dry emergency. What you have is a BA lacking a dry emergency, and as such it is not safe. Not pointing out anyone in particular, but it amazes me at how frivolously the risk is dismissed. Obviously, they have never experienced a catastrophic siphon system failure, but it could happen at any moment, day or night, home or away on vacation. Sure there are things that can be done to minimize the damage, to an extent, but they involve more work, and more $$ than if the system was designed to be as safe as possible (no such thing as 100% with aquariums) at the start.
Self adjustment is very nice to have. However, since the variations in a Herbie system are not that extreme, it is not worth the risk. (slight tweaking from time to time, and dialing it in may take a bit longer.) Ambient conditions do affect these systems, but if you have extreme variations in any of these systems something else is wrong. Good drain line maintanence applies here. We had a great example of this, a couple years ago. It was not the drain system, it was the pump. Were the OP running a three pipe bean rather than a two pipe Herbie, the problem may have gone unoticed till the pump ultimately failed. I don't know the outcome of that issue...
Proper Herbie self-adjusts. Water level increases, flow rate increases. Water level lowers, flow rate lowers. It is an operational characteristic of these systems. BA has a much wider range of self-adjustment. If wanting a wide bandwidth build a proper BA, it is NOT worth the risk. One can listen to experience... or not. Up to them.
The open channel is the current prime target for tinkerers, and is where the most damage to system function is done. It is obviously the least understood part of the system,...
uncleof6.... nice response... I read it a few times.... please grade my response and make sure I am understanding...
1) More flow, higher turn over of the DT water into the filtration area is goodness.... thus my 2000gph goal is a "good thing".... and my Beananimal with 1.5" bulkheads and 2" pipes ought handle that nicely.
2) Thus, I am creating a multipass system using your lingo... If I also add good 'vertical' mixing with power heads, I should get the water in the tank into the sump 10x per hour.
3) Question, why does it particularly matter where the skimmer is??? The "bad stuff" is in the water column regardless of what tank it is. Doesn't it really just need to be "somewhere". As long as the water column is well circulated, all the water eventually goes by the skimmer. Want to understand why it needs to be in the sump other than "convention".
4) RDSB vs refugiums... read a bunch a few years back when I was setting up my 120g and was steered away from the RDSB's. I've got the 120g servicing my 210g DT... it can be a RDSB or a fuge... it there a thread you recommend on learning about RDSB? I'll start searching and reading in the meantime.
More later, thanks
M
I agree that the open channel is the least-understood part of the system. At steady state, it's basically a Durso standpipe, just modified so that the air intake will occlude at the right time. The problem is, I don't think many people really understand how a Durso works. A siphon is a pretty simple concept, but a standpipe with water flowing and entering air to keep the water flow laminar and quiet is much more complicated physically and conceptually.
The fact that people tinker with it more is also not surprising, since that's where all the 'action' (magic?) occurs in the system. The siphon is a siphon. Not much to see or change there. The dry emergency is an open pipe that may get a bit of flow at startup and otherwise sits empty. Not much to play with there, either, but the open channel is just ripe for tinkering!
The other issue is people don't fully grasp the interaction between the 3 channels, or how they work in various failure modes.