Gravity-fed Auto Top-off System
- Thread starter Random Aquarist
- Start date
HippieSmell
Occupy Reef Central
Ok, maybe this will help.
As you can see, it's a jug with 3/4" pvc attached with a uniseal. I put silicone around the seal for extra safety, but not necessary. The pvc comes straight out, then in the second picture you can see where it elbows down into the return section of my sump. There is also a ball valve which is needed to close the pipe when filling the jug through the cap in the jug (pic1).
There is a thin styrofoam gasket in the cap of the jug, and it has worked for me for about a year, but you may feel better with a rubber gasket. I see no reason to replace mine.
You can also do it the way bolrog did his, and that was the way I did it my first time, but it's more complex. For my method, you must use rigid piping (hence my use of pvc), and in both cases the jug must be above the water line in the sump. There's no electricity, no moving parts, and it's cheap, probably $20. Much less if you have the stuff laying around like I did.
As you can see, it's a jug with 3/4" pvc attached with a uniseal. I put silicone around the seal for extra safety, but not necessary. The pvc comes straight out, then in the second picture you can see where it elbows down into the return section of my sump. There is also a ball valve which is needed to close the pipe when filling the jug through the cap in the jug (pic1).
There is a thin styrofoam gasket in the cap of the jug, and it has worked for me for about a year, but you may feel better with a rubber gasket. I see no reason to replace mine.
You can also do it the way bolrog did his, and that was the way I did it my first time, but it's more complex. For my method, you must use rigid piping (hence my use of pvc), and in both cases the jug must be above the water line in the sump. There's no electricity, no moving parts, and it's cheap, probably $20. Much less if you have the stuff laying around like I did.
Random Aquarist
New member
I'm still confused as to how this works. Why doesn't it all flow in?
HippieSmell
Occupy Reef Central
The water doesn't all flow out because the jug is at a lower pressure than the outside atmosphere, just enough so that it counteracts the force of water trying to push out through the drain pipe. When the water level in the sump drops below the end of the drain pipe, it allows air to be sucked up into the jug, giving that gurgle noise. The extra air relieves some of the negative pressure in the jug and allows the water to flow out. When the water level in the sump reaches the height of the end of the drain pipe, the flow stops because no more air is allowed to be sucked in.
It just works, ok?
It's a hard concept to grasp sometimes, but once you see it in action you'll understand. Like I posted earlier, do the cup in the sink thing, it should help.
It just works, ok?
It's a hard concept to grasp sometimes, but once you see it in action you'll understand. Like I posted earlier, do the cup in the sink thing, it should help.
Last edited:
Sorry about the late reply but it is due to the difference in atmospheric pressure. It just that the out side has more pressure and so it's like the water is being pushed up the water transfer pipe. Until the air intake is exposed and the pressure equalizes the water will not flow.
But make sure that the air intake is a little below the wax level.
But make sure that the air intake is a little below the wax level.
cotter4601
New member
What is the wax level?
Random Aquarist
New member
Thank you very much, guys. I now know how to make it. However, I'm still confused as to what makes PVC pipe considered "rigid".
Bolrog meant the max level, in the sump.
Hippie, interesting device. I have seen a similar setup, where a jug full of kalkwasser is held by a bracket upside down over the sump, with the opening of the jug just under the top of the water in the sump. Your design looks less likely to fail and have the water all rush out at once.
elegance coral
They call me EC
I have been adding kalk like this for years. Back in the day I used an upside down water bottle like the one in Hippie's pick but I only had one pipe hooked to the opening of the bottle. Air entered and kalk left through the same pipe. It was a short straight pipe with a cut off valve in it. I used a rubber conecter with two hose clamps to attach the pvc to the jug. The pipe was cut off where I wanted the water level of my sump to be. Then the kalk started to make the jugs brittle ( or they just got old)and they would crack. Not a good thing. I went to one of the newer bottles exactly like Hippie's, with the handle in the side. It imploded. Still not a good thing. I now use the same principle but with pvc. I have a 6" dia. pipe about 4' long. on one end it is reduced down to 1/2" with a cut off valve. The 1/2" pipe also extends up inside the 6" pipe a few inches. I have a rubber cap made for 6" pvc on the other end held on with a hose clamp. This works much better. no cracking, leaking, or imploding. now I mix my calk and fill it once a week and forget it.
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