DIY overflow system

[Melvin]

Have try it, very satisfied

DIY overflow system.....any comment...

[CalciumReef]

[Melvin]

[uncleliew]

awesome! bro.

pls try on saltwater tank and show the result.

rgds,

unlce liew

[thc]

Wow, solid men. double thumbs up

[porc]

great job... you've incorporated a surface skimmer too. well done!

have you thought of shifting your output further up? your input must be all the way into the bottom of the surface skimmer outer tube right? I would worry about the siphon breaking when the return pump fails, cause the water level inside the outer tube will fall all the way down to the level of output (near the bottom). and being so close to the input, it might suck sume air in too and break the siphon...

and by the way what is the size of your pipe and how high flowrates can it handle?

cheers...

[Melvin]

Hi Brother, if u want to reduce the flow rate than u may thinking of shifting the output upward..(The higher u move...the lower the flow rate)

The input is approx 1-2cm above the bottom of the surface skimmer.

Don't worry the siphon will not break during the pump fail.(100% will not fail)(tester)

(remenber the fill cap for intial start up have to be remove once siphon is achieve / during cycle)

The output is at the safety lever (still can lower some more about ~1cm)

The piping size around 20 mm(Don't think that it cannot achieve high flow rate)

The flow rate can achieve up to 300gph no problem.

[thioeh]

Hi brother Melvin,

Very interested in the overflow system you DIYed. Can you do 1 set for me please? You may PM me the price. Thanks!!

[five for fighting]

me too...can u diy for me too.i'll pay u...thank Q..btw ur overflow system is damn NICE!!!

[Melvin]

Hi, five for fighting just PM u...

[rockfish]

hey! bro melvin!

i make one of this too ... like u said the higher the water level control point is, the slower the flow.

therefore, i modified the design too .. and it seems to a bit simlar to urs. but i think urs looks chio'er.

[Marinedisc]

I luv DIY. Yours very chio. Bravo...

[porc]

Hi Brother, if u want to reduce the flow rate than u may thinking of shifting the output upward..(The higher u move...the lower the flow rate)

Hi Melvin,

i don't think this statement is correct. flowrate is not determined by the height of the output. It depends on the return pump flowrate. the more water you pump back into your tank, the higher the flowrate of the overflow device.

Cheers...

[charlie]

Hi Brother, if u want to reduce the flow rate than u may thinking of shifting the output upward..(The higher u move...the lower the flow rate)

The input is approx 1-2cm above the bottom of the surface skimmer.

Don't worry the siphon will not break during the pump fail.(100% will not fail)(tester)

(remenber the fill cap for intial start up have to be remove once siphon is achieve / during cycle)

The output is at the safety lever (still can lower some more about ~1cm)

The piping size around 20 mm(Don't think that it cannot achieve high flow rate)

The flow rate can achieve up to 300gph no problem.

Hi,

Melvin,

Care to share your DIY experience? some question to ask:-

Q1. How to do the initial startup?

Q2. Adjustable surface skimmer, Can you show the cross-section of it?

Q3. How much does the whole things cost.

Thanks

Very nice.

[Melvin]

HI, five for fighting already PM u....

[Melvin]

Hi brother porc, the height differance between the input water lever in the surface skimmer collector and the output pipe will determine/affect the flow rate...

(If u have a strong return pump and maintain the water lever at the collector is at the top of the surface skimmer the flow rate will be at MAX....so that during the water lever in surface skimmer reach the lever of the output then the flow rate will be MIN../stop flowing...)

Hope U understand.....

[aStRoBo|]

great DIY idea.. dun tink we need a big overflow box too eh? tink this is enough to siphon the water out..

[Melvin]

Hi aStRoBo, for yr support..

[porc]

(If u have a strong return pump and maintain the water lever at the collector is at the top of the surface skimmer the flow rate will be at MAX....so that during the water lever in surface skimmer reach the lever of the output then the flow rate will be MIN../stop flowing...)

Hi bro melvin,

Remember the law of conservation of mass we learnt in school. The system in this case is the water in the main tank. What goes in must come out. If your return flowrate is high, and if you say you can adjust your output flowrate by the height of the output to the extent that the output can be minimum/no flow... then where would the rest of the water go to? the main tank would overflow...

Your analysis is only partly true. the water flow rate can be affected by the level difference between input and output, but in this case it is only true in the static case (when everything is frozen at a point in time and analysed). What we have here is a dynamic system, which has yet to equilibrate. There's much more to explain but in short, at equilibrium the output flowrate WILL adjust and be equal to the input flowrate.

case example: 2 identical water tanks at the top of 2 identical HDB blocks serving 1 flat per block. the first flat is on the 6th floor and the second on the 9th floor. assume that both tanks are being topped up at a constant flowrate (say 100 l/hr). yes it's true that the initial water flowrate (when you just turn on the tap) will be higher on the 6th floor as compared to the 9th floor, but the systems here are not in equilibrium yet. Let's say your initial flowrate on the 6th floor is 200l/hr and 150 l/hr on the 9th floor. since the inputs to both tanks are less then the outputs, both tank levels will start to fall (at different rates). as the level falls the flowrates in both flats will also fall to less than 200 l/hr and less than 150 l/hr respectively due to the reduced pressure difference. Still the system is not in equilibrium. The equilibrium is only reached when both tanks are empty and the 100l/hr pumped into each tank flows down to the respective taps almost immediately. At this time both taps will only give 100l/hr max, irrespective of what level they are on...

P.S. no offence bro. i'm not intentionally trying to rebutt you point after point. I enjoy a lively debate. both of us are quite adamant that we are correct. Actually I'm hoping for more others to join in... Any physicists, fluid dynamicists, mechanical or chemical engineers out there care to comment??

Cheers,

porc

[Melvin]

Hi brother, for sharing.....

[patrick123]

Proc,

I understand your point about the fact that a faster pump will increase the differentiate between the water level and hence it will help to improve the speed of the inflow. However, if the pump is too powerful, what will happen is that you output is faster than your input and your sump will run dry...or your main tank will overflow.

I think what Melvin is trying to say is that if you increase the difference in water level, the water will accelerate much faster and hence improving the inflow. For example, if you drop a watermelon at 2ft high, it may not break, but if you try to drop the same watermelon from 3 storey high, the melon will smash into piece. This is because they are not travelling at the same velocity anymore, the acceleration makes the difference.

Best Regards,

Patrick

[patrick123]

Melvin,

What I suspect is that your DIY siphon will only siphon water up to the level of the skimmer. Meaning that the lower portion of the bigger PVC pipe is useless.

This is because if water goes below the ###### hole on the skimmer, the air will be suck in and break the siphon. So water will no longer go in until the water level reaches the high side of the skimmer and start to cover up all the holes.

Please correct me if I'm wrong.

Best Regards,

Patrick

[Melvin]

Hi brother u r worry, the water lever in the surface skimmer will not reach the end of the input pipe mean when the water lever reach the lever of the output pipe/min water l;ever (shown in diagram red line) the flow will stop. During the cycle the return pump will pump the water up and achieve the height differance of water lever in the surface skimmer then the flow will start again..

Hope u understand....

[patrick123]

Melvin,

Thanks for the explanation. I take a look at your picture again and I finally understand. Inside the big PVC pipe, there is a smaller pvc pipe, and the water from the skimmer will be drawn down to the bottom of the pipe and get sucked out. This is a very good design I have to admitt.

Just one more question is, the Min water level is very low. Close to 3/4 down before the siphon will stop. Do you have a sump this big that can hold so much water (3/4 of the tank) in case if the return pipe fail?

Thanks,

Patrick

[patrick123]

Please see the picture below with the red arrow.