Backyard Aquaponics
A place to discuss aquaponics

Hi there!

I have a question concerning no holes overflow.

What is the maximum diameter pipe you can use?

I have a big tank that has a tank liner, and I don't want to puncture the liner or tank (1/8" steel) if possible, but I need like a 4" overflow. If I could do a 4" no holes overflow, that would be great, but then I got to thinking that 4" might not work (too big).

If that is the case, then I need to do several smaller ones. How small do I need to go? Would a 2" work? How about 1" or 1.5"?

What is the max size?

ok, looking through the forum, I've seen folks use 1.5" pipe, so maybe the max is a bit more. I have used a bigger siphon, but never a no-holes overflow.

I think the biggest I've used so far is 2.5"

well, 2.5" is pretty good.

I found a 4" one online for an aquarium: http://www.bio-elite.com/waterbridge.htm

So, I am going to give it a try with some 4" pipe pieces I have.

Most of the time, it won't be overflowing, only maybe 2-3 months out of the year, so it will be easy to monitor.

another question, what is the max height between the tanks? And is there a relationship between max height and pipe diameter?

I am getting nervous about the high risk of failure with a no holes overflow. The tank is 7,000 gallon rainwater tank, and a failed overflow could be a big problem.

So, does anyone know how to make a hole in 1/8" steel without destroying the liner?

Can you Move the liner out of the way, and use a holeSaw to drill through the steel, then using a sharp razor blade cut the liner hole where the steel is cut.

i would fill the tank upto the hole after you cut the hole in the steel as the liner may stretch once u fill it then i would fit a bulkhead or tank fitting with rubber washers and you could even use some silicone to seal it all up, should be fine.

iv put 40mm bulkheads in then filled them up 5 mins later with no leaks as i cut my holes to perfect size.

i used a 50mm No Holes Overflow for about 2 months, but the stress of it failing was far too high. iv seen many failures on here cause fish deaths, the less items that can fail easily the more stable your system will be.

yeah, I will have to give it a try, pulling the liner back and doing a hole with a hole saw. Now, I have to find a hole saw that will fit a hand-held drill, cause the ones I have will only fit a drill press (large chuck).

I am nervous moving the liner out of the way. it is on a track, and if it fall, there goes the water. Getting to the area is the tricky part cause the man hole is about 2 feet from the wall.

But, I am sure I could get it done, if I go slow and carefully.

I had two 100 mm DWV no holes siphons (as distinct from overflows ) for my first and second GBs. They worked and if I were to build them again I recon I could get them to work fairly reliably. Espeacially if I was using a standard sump rather than my eperimental sump.

If ther is a great demand I can do a right up on the problems I had and how I would make a more reliable version but I would conlcude that using another option would be a good idea because there are so many options that are so much easier to get working reliably. I guess if you had some sort of tank where you just did not have the option of putting some sort of hole in the side or the bottom then they may be the best option.

If there is demand I'll right it up other wise use an overflow with a hole

Why would there be any limit to the size? Does water denature under a certain negative pressure or something. Something like cavitation?

We have a pipeline that carries water from the murray river to adelaide (70km or so) that rises up a few hundred metres to get over the adelaide hills. It has some very large pumping equipment, but I always imagined it would act as a stinking great siphon. It never occurred to me that there might be a limit as to how big a siphon might be, other than the practical ones of getting it full in the first place, and making sure there is enough flow to keep the inevitable air bubbles moving

I would guess that the maximum size would be that which restricts flow enough to create a current sufficient to move the tiny bubbles that fall out of water, and stop them collecting at the top of the siphon and ruining everything.

I seem to remember being told that to stop the creation of a messy cut in the exit hole when you are drilling, clamp something sacrificial to the exit side. ie some wood. Then you should be able to drill through anything without damage.

eg to test, place a paper towel between two scrap bits of wood, clamp tight and drill through, the paper towel should be fine, and have a nice neat hole if there was lots of pressure all around it.

Should. Should. Should.

read that last line again

Bullwinkle the max you can siphon or suck with a pump is about 22 ft
I hnow a bloke who had a 500 ft hill on his property he put a bore 400 ft deep and tried to siphon water down to his property when i told him it wouldent work he said he asked the local shire engineer and he said it would
Pretty expensive experiment

ouch

Do you know why it doesnt work?

Pressure - about 10m height difference is the limit.
http://en.wikipedia.org/wiki/Siphon has a good description in the last paragraph of the "Theory" section.

Basically the low pressure at the top of the tube makes the dissolved gas come out of solution/water boil and the gas breaks the siphon.