porc

okie... understand your reasons for wanting a bottom inlet... let me try to analyse... I think you can drill some holes towards the lower half of the cylinder, but the holes cannot be too big. must keep it small so that there will always be extra to overflow from the top. Also, when the pump fails the water level in the main tank will fall all the way down L2. If your sump can hold that amt of water then i don't forsee a problem...

the open air valve will break the siphon. it will not work...

oh.. to add the siphon will work if the main purpose of the air valve is to extract air during priming of the siphon and will be closed during normal operation.

okie understand now... you don't want to hijack other peoples thread... but you should describe your system more. what you want to achieve and what you have in mind. based simply on your question i would say yes the siphon will work, but without further information i can also say that the siphon will empty half your tank.. let us know more and we'll try to help you... cheers...

see http://www.sgreefclub.com/forum/index.php?showtopic=15023 . there's a full discussion going on there right now...

last pict. underwater view. oh yes. the green tubing is there to draw out the air to create the siphon in the 1st bend. the cylinder is 50mm and the overflow piping is 25mm. my return piping is 13mm.

pict of the "skimmer" cylinder...

some picts to share. forgive the quality and mess... overall view... the bends are contorted in this way simply to conserve space...

the open end top is to allow air in sspecifically to break the siphon in the second bend, otherwise it's a full siphon again and no different from your original design... it is actually part of a durso design that can actually help reduce noise. you add an end-cap there, drill a hole and add a small air-valve to control the air intake. supposed to reduce the slurping sound but i find that it makes no difference for my case so i just leave it open... check out http://www.DursoStandpipes.com do you have a fine sandbed? if your circulation is so strong to stir up debris wouldn't it stir up the sandbed too. don't know how well it would work. I have no experience on this. i normally just clean my sandbed while doing water changes... hey, i believe that before this you tank is already cycled and has been working without a sump right, which actually means that filtration has already been going on successfully in your main tank itself already. IMO a sump is just additional filtration or more space for a refugium, skimmer and other equipment etc so flowrate is not too crucial. I myself am using just a recycled big boy overhead filter pump. rated only 1200l/h but definitely much less with the 1/2 m height it is pumping up... sometimes people tend to overkill on technology. I believe sometimes by simple logical reasoning you can realise that some "recommendations" are unneccessary...

This is the design that I'm using now. The only difference is in the addition of a cylindrical pipe of larger size than the overflow pipes. In this case L1, L2 and L3 is equivalent to those in my earlier design. during operation, water level in the tank will be at L5 which is slightly (abt 1cm) above L4 (which is the length of the cylindrical pipe) and overflowing into the cylinder. The input to the overflow is placed into this cylinder and is actually drawing water from this cylinder. Similar to before, L1-L2 is the water level difference driving the flow through the pipes. Adjust L2 such that L1 is as close to L4 as possible. so that there will be minimal bubbles from water splashing into the cylinder. make L3 as low as possible so that bubbles will not get into the pipes. bubbles accumulating in the pipes would break the siphon sooner or later. when the return pump stops, water level in the tank will drop only to L4, whereas water level in the cylinder will drop to L1. siphon is still maintained. when the return pump regains function everything will continue working as normal... BTW, a disclaimer here... i don't take credit for these designs, which are based on simple principles. many other people have thought of these designs too and have successfully implemented it. whenever i say "my" design i simply mean the design that I'm using...

I assume you mean that you adjusted L2 right? L1 would then naturally equilibrate itself. Firstly, I think 13mm siphon piping is not big enough. imagine on one hand your powerful pump is pumping in 2200l/hr through a similar 13mm piping, and on the other hand we want a natural equilibrated water level difference (L1-L2) to push water at the same rate. I would expect the the level difference required to be quite big. 25mm piping should be good to handle the large flowrate with a minimal L1-L2 difference. Secondly, I suspect your design is slightly complicated by your wanting for a bottom inlet in addition to the surface skimming. If L1 is too high L2 will correspondingly rise above the skimmer, utilizing both inputs but eliminates the skimming action. whereas when L1 is too low the water can still use only the bottom inlet alone and thus L2 is below the skimmer inlet.. I really cannot think of a good solution to this... but if you evaluate your current tank situation and think that there is already enough circulation in there anyway then maybe a bottom inlet is not neccessary and you can use the following design explained in the next post which I have successfully tried. hmmm... where are you going to place the valve? If you place after second bend don't forget that there is an open top there. whatever you restrict will just overflow from the open top. If you place the valve in the first bend itself, you are effectively just adding more friction thus requiring a larger L1-L2 level difference... that's what I can analyse for now... well, if you do try it out let us know the results...

Sorry for the late reply... was busy last 2 days... from your discussions it seems you are currently considering something like your original design. You can try that out but here are my 2 cents more... 1) too many parameters are being controlled. your pipe diameter, no. of elbows, pipe length, pump capacity, water level, height of input and output (ie. pressure head), valve opening etc all affects the frictional force and therefore the flowrate, which you are hoping to control. you will end up with a system with a narrow stability band. My proposal is actually an overdesign in terms of flowrate using larger pipes etc but more failsafe. The only parameter here to consider is the allowance for L1-L2 (see details below). 2) therefore tuning may not be easy. but I must also qualify here that I have no real hands-on experience on these systems (as I find the design not up to my own Hazops standards to be implemented and tested), but I do understand such systems theoretically and they are prone to instability outside of the equilibrium state especially if they are introduced abruptly(eg. you stick your hand in and increase the water level by a fraction of an inch, or some debris clogging your pipes etc). However some reefers here have done it with no problems so it's not impossible. 3) One of my more highly probable hazop scenarios would be power failure (ie. loss of flow in return pipe) followed by power recovery (resumption of flow). after loss of flow your tank will not empty (good!) because you have drilled your hole. but the hole will also cause a break in the siphon (bad!). when power returns your overflow is not primed and you know what happens next... if you have a system that solves this problem then good. As for your earlier questions I'll answer them since you've asked... Correct! In a way you are correct. but based on normal usage water level will not fall below L2. Assuming your return pump fails, your water level will fall from L1 to L2 and stop there. The water (ie. siphon) in the 1st bend will still be there and ready to continue when your pump kicks back in. Absolutely correct. most people have trouble understanding this part. It is precisely this water level difference here (and not the outlet) that is pressuring the water thru the pipe. The higher the pump pump rate, or the smaller the pipe size, the more allowance you need for L1 above L2. Yes. you can incorporate a surface skimmer in exactly the same way you designed your original piping in your first post. I just don't have it here because the diagram was drawn much earlier and I just reused it. There are other ways if incorporating a surface skimmer, but there are more also considerations if you want a mid-tank input. We can discuss more if you are interested. cheers, porc

haha! I had a long argument with a fellow bro here on this. you must have read that. my explainations and examples were as clear as I could make it... I still maintain that what goes in will come out and is independant of the height difference. well, you can choose to believe him or me... your current design is based on a full siphon on the return pipes. IMO not a good design because it is very difficult to tune and the "what goes in = what comes out" rule doesn't apply. For the rule to apply you just need to add a few more bends in the piping. See my diagram below. Similar to yours except no surface skimming and the additional bends. the blue part shows the water and in this case explains why what goes in will come out. hope this helps..

i don't blame nkf. i don't blame the celebraties... the biggest culprit behind all these tomfoolery is mediacorp and mediaworks. mediacorp is doing nkf and mediaworks is doing ren ci... they are just trying to outdo each other... believe me... most probably tomorrow the first thing you'll see is trailers all round boasting that the show has garnered XXXXX viewership... These media executives are the ones pushing their employees (ie celebraties) with outrageous stunts... they are the ones trying to suck all the benefits by playing on viewer's emotions...

I'm facing this exact same problem right now. But i observed that the nudis seem to be attacking only the zoos and my zoos are all closed right now... You might have taken the zoos out but I think the problem will be exterminating the nudis on the zoos and ensuring that they are all gone before you put them back in. I'm now in the nudi exterminating mode... any nudi that i spot on my zoos will be destroyed... that's my modus operandi for now... but would like to hear from others who had faced this problem before...

just wondering whether anybody ever tried adding wheels to their stands. I'm the kind who likes to rearrange furniture regularly and it would be nice to have a "mobile" tank too. just some quick calculations... a 3x2x2 main tank and 2.5x1.5x1.5 sump together with water would weigh about 500kg. LR and sand maybe add another 150kg. the rest of the equipment would be minimal, so total weight would be say 700kg. if i were to make a comparison to those 4-wheeled trolleys. I remember when I was in school last time we did try to squeeze 6-8 teenagers onto one trolley and push each other around. we would have weighed 300-400kg combined and the trolley could still take all our weight. So if I'm really kiasu and add 8-10 castor wheels to the stand, should be no problem right??? anybody else have more scientific way of determining whether it is safe? do the wheels that we buy at the hardware shop come with a recommended load??? cheers...

tap water should be good enough and I believe they are already calibrated. I tried mine directly with tap water first and the reading was 1.00. so no need for further adjustment.

Hi, these 2 shrimps are too large for my crowded tank. selling at $10 each. preference to sell both together. Will post photos tonight if anyone is interested. Self-collect at upper thomson this weekend. please don't flood my pm and indicate through this thread and I'll get back to you. Note: I'll choose who gets the shrimps. (ie. may not sell to the fastest fingers...) cheers...

nice diy... but there has been advice earlier that the optimum orientation for the bulb during operation should be with the nipple on the bulb pointing upwards (ie. towards the sky away from your water surface). in this case the nipple will be facing to the side. but to think of it mh lights are also used as building floodlights and arepointing in all sorts of directions, so there must be times when this orientation cannot be adopted... wonder what is the effect???

this thread refers to a slightly different problem of backflowing through the return pump when it is off. will only partially solve trader's problem. if he punctures a hole in his overflow siphon just below the waterline, he can prevent his sump from overflowing, but the retun pump will continue pumping and even if there's enough space in the main tank to hold the increased water without overflowing, his sump will be sucked dry... but on the other hand, you may end up ruining a pump but at least your floor stays dry... my advice is to either get the i-box or diy an alternative like the following thread http://www.sgreefclub.com/forum/index.php?showtopic=12846 or an earlier thread which is basically the same design and easier to construct as it does not have surface skimming. http://www.sgreefclub.com/forum/index.php?showtopic=12591

your problem should be due to your overflow. think it's basically a full siphon that you're controlling with a valve. very hard to tune and once out of whack the your sump will either flood or dry up. there's another thread in this section on diy overflow with a simple but great design. construct a proper overflow and your problem will vanish. what comes down the overflow will only be as much as what you pump back to your main tank...

you want a green spotted puffer fully acclimatized to marine? doing well... btw how big is the goby?

should be suitable for a 3ft tank. anyway it has just been reserved. if anyone wants to join the reserve list just post here. cheers...

ok. have checked out the price of the pump. decided on an eden 214 for $35... So how, anybody wants the UV filter for $35??

Hi, Brand new in box (never used) Jebao UV sterilizer Model JUV-06G for sale. An earlier piece was faulty and was replaced by the manufacturer for the current piece which has not been used. Bought at $58. Looking at selling it at the cost of an Eden 228 rotating pump (haven't found out price yet). whoever wants can either give me the $$ or just buy me the pump if you know where to get it cheap. Collection either at buona vista or upper thomson. Some tech specs: i) 240V 50Hz 6 Watt lamp. ii) Jebao JB-1500 aquarium pump (HMax 160cm, FLmax 900L/H) and tubing included Please post directly in this thread and I'll respond asap. cheers, porc