View Full Version : Gravity-fed Auto Top-off System

Random Aquarist
01/15/2007, 10:28 PM
What kind of container could I use to attach a bulkhead and tubing to w/out modifying it? I'm not a very good DIYer, so can someone help me out?

01/15/2007, 11:22 PM
Just about any container will work. I use a 5 gallon bucket that has a fitting like this (http://www.marinedepot.com/md_viewItem.asp?idproduct=RO5353), though I bought mine at Home Depot and scored a couple O-rings that fit the MPT for free, which is just connected via 1/4" poly tubing (also HD) to a float valve in my sump. I drilled a hole just slightly smaller than the MPT and merely screwed it in, with an O-ring between the fitting and the bucket.

No electricity, just physics.


Random Aquarist
01/15/2007, 11:32 PM
Can you please translate that into Stupidian for me please?

Can you please find an example on HomeDepot.com for me. I don't know much DIY jargon.

Random Aquarist
01/15/2007, 11:35 PM
Maybe I should just get a container, drill a hole in it, and epoxy/glue the tubing to it. I'd then add on the float valve.

01/16/2007, 12:38 AM
Don't glue the tubing in, it will fail eventually. Use a uniseal. http://www.aquaticeco.com/index.cfm/fuseaction/product.detail/iid/8600/cid/2009
I also use a 5 gal water jug from walmart, pvc, and a ball valve. That's it. The jug is exactly like this one:http://cgi.ebay.com/5-GALLON-WATER-JUG-CONTAINER-PLASTIC-BOTTLE-COOLER_W0QQitemZ180003032842QQihZ008QQcategoryZ48318QQcmdZViewItem

01/16/2007, 08:04 AM
What kind of float value did you use?

01/16/2007, 10:32 AM
There is no float, just gravity.

01/16/2007, 10:37 AM
How do you get it to stop and start when it's needed?

01/16/2007, 10:57 AM
Fill a sink with water, submerge a cup, flip the cup upside down under water, slowly lift cup out of water. Same principle.

01/16/2007, 12:11 PM
Could you post some pics of the design. It sounds interesting and I would to see how you did it.

01/16/2007, 06:55 PM
I am interested in this design as well. Please expeound:) Type slowly.

01/16/2007, 08:31 PM
I'll see if I can post some photos to clarify.

01/16/2007, 09:40 PM
You can see my gravity fed ATO system on this page of my tank thread.


01/16/2007, 09:48 PM
I am using a siphon and a float valve. Kent float valve at most aquarium supply places. Drill a 5/8 inch hole in the sump, or the holder you want to use, thread the valve on, attach tubing, and start a siphon from the raised bucket to the sump. It will shut off when full, and open as water is evaporated.

01/17/2007, 05:57 AM
Thanks, now I have to add this to my list of DIY projects.

01/17/2007, 08:01 AM
Still interested in the design without a float valve.

Random Aquarist
01/17/2007, 08:03 AM
Me too.

01/17/2007, 08:31 AM
try a search under nurce

01/17/2007, 08:51 AM
It is a sealed air-tight container above the waterlevel whether of the display or sump. It will have 2 hoses/lines from the container to the water level. Both lines should have some kind of shut-off.

One line will be longer than the other in the container but not as deep in the sump/display. A rigid tube is best because this needs to be as high into the container as possible. This will be for air intake.

Second line will be deeper into the display/sump and just barely into the container. This will be for the water transfer.

Fill the container and place it into the final location. Place the air intake at a little below maximum water level in the display/sump. Then place the water transfer tube 2 or 3 inches or more lower than the air intake.

For the first time don't put a lot of water into the container. (in case of leaks) Open the valves and as the air intake sucks up air it will displace water from the container through the water transfer line into the display/sump. As the air intake is covered by the new higher water level it will stop displacing the water in the container and the flow should stop until the next time the intake is exposed.

The reason I said to put the air intake a little lower than the max waterline was even with the air intake coverd a little transfer will still happen until some water is in the air intake.

At this time the check for leaks. It is preferred that you use some type of mechanical uniseal not silicone because as stated earlier they will eventually fail.

If you have no leaks, GREAT (it took me 3 tries to get this right). Siphon some water out of the display sump and make sure everything is working right.

One mod you could do is put a fill valve on the top so instead of removing the whole container and lines you can shut the valves and open the fill hole and seal it afterwards.

Random Aquarist
01/17/2007, 08:56 AM

01/17/2007, 09:06 AM
What do you not understand???

01/17/2007, 11:16 AM
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.

Random Aquarist
01/17/2007, 01:29 PM
I'm still confused as to how this works. Why doesn't it all flow in?

01/17/2007, 01:40 PM
Do you end your rigid pipe right at the max fill line on the sump? Will a water level lower than the end of the rigid pipe alow air into the pipe causing it to "glug" until the pipe is back under water? Still a little confused as well. Thanks for being patient.

01/17/2007, 01:58 PM
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.

01/17/2007, 02:03 PM
I think I got it....thanks.

01/17/2007, 02:32 PM
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.

01/17/2007, 02:57 PM
What is the wax level?

Random Aquarist
01/17/2007, 04:51 PM
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".

04/12/2007, 06:22 PM
<a href=showthread.php?s=&postid=9006298#post9006298 target=_blank>Originally posted</a> by cotter4601
What is the wax level?

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
04/12/2007, 07:17 PM
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.