Speed drain-fed scrubber

[Devs]

Indeed... and very nice it is to...but...

A lot of people just want to buy things in boxes, take whatever it is out of the box, plug it in and along with a few guide lines/instructions voila !

[Amphiprion]

Okay, after measuring the dimensions of my overflow box on my 40g, I won't be able to incorporate a 3rd hole. That shouldn't be a huge problem, because I'll be taking plenty of precautions as already mentioned on here. I'm pretty excited about this build and tank in general. It will also be the first tank I've had that has been "scrubbed" from day one. Will begin to document things in another thread as I make more progress. Things are moving slowly but surely right now. I'm trying to get all my ducks in a row before I really attempt to do anything.

[sklywag]

I have no pictures since I deleted them. But I have always fed mine from my overflow. My last tank had a dual overflow in a single box like it sounds like yours is. So I used one and the other was an emergency overflow.

My current tank is a single overflow in a single box and I'm using a strainer to keep anything large from intering pipe. No emergency plan.

You wont be able to use a Herbie style on a overflow feed. Why? Because the pipe wont be under water in the sump as it need be creating the syphon effect. You can if you feed it from a seperate pump. I ran a Herbie when I used a skimmer. If it weren't for the skimmer that tank was dead silent. That's how I stumbled onto scrubbers. Turned off my skimmer one day and never wanted to plug it back in.

[Amphiprion]

I have no pictures since I deleted them. But I have always fed mine from my overflow. My last tank had a dual overflow in a single box like it sounds like yours is. So I used one and the other was an emergency overflow.

My current tank is a single overflow in a single box and I'm using a strainer to keep anything large from intering pipe. No emergency plan.

You wont be able to use a Herbie style on a overflow feed. Why? Because the pipe wont be under water in the sump as it need be creating the syphon effect. You can if you feed it from a seperate pump. I ran a Herbie when I used a skimmer. If it weren't for the skimmer that tank was dead silent. That's how I stumbled onto scrubbers. Turned off my skimmer one day and never wanted to plug it back in.

The other end doesn't need to be under water to create a siphon (you wouldn't be able to do water changes with a plain vinyl hose if that were the case). In this case, it just needs to have some sort of resistance, like a ball valve. Once the overflow water level rises after applying back pressure, it will siphon just fine as long as the other end is lower than the drain.

[Floyd R Turbo]

Amphiprion, I understand what you're saying about the siphon principle, and while you are correct, there is a difference between a siphon hose to clean your tank (which is usually small diameter) and a siphon line for an overflow system (usually 1" ID). The larger the ID and the longer the vertical run, the more water that line is capable of flowing, and a line that is terminated under water at both ends has the maximum flow rate possible. The valve allows one to control the flow rate while keeping the line full of water. One of the principles behind the BeanAnimal or Herbie overflow systems is that you must terminate the siphon line under the water's surface (about 1/2" to 1") so that the line will purge all the air out in order to maintain the full siphon, which maximizes the flow through a pipe. One of the reasons for this is to remove the tendency for high-flow water crashing into the sump to create massive amounts of bubbles. Another is for versatility - if there were a change in water level (from sticking your hand in the tank, then removing it) the siphon line would have to restart. Without the line terminated below the water, the air my or may not ever purge out of the line, and you may not have a full siphon i.e. maximum designed flow. This happens, trust me. When I stick my arm down to the bottom of the tank, I can hear the open channel kick in, then if I remove my arm too fast, siphon sucks the box dry and has to restart. My system restart time is about 10 seconds from pump off to full siphon and balanced system, dead silent, no bubbles in the sump at 3000 GPH through a 1.5" drain.

If my system had the drain terminated above the water line, the water would fall out of the pipe and allow air into the line, causing a reduction in flow and much noise and bubbles. My ball valve on the line is a Cepex valve and is about 90% open

[MorganAtlanta]

My design has since changed, but I ran my scrubber off a herbie drain for several months with no issues of not keeping a full siphon.

[sklywag]

I think Floyd cleared my statement up pretty clearly. You may be running a Herbie standpipe as I am doing as well. Just a straight pipe. No elbows or other fittings. It too is submerged under the waterline in the overflow box to eliminate air and gurgling. But it is not running on a siphon. If your return pump is not sucking water through it, it is not on a siphon. And thus not a Herbie or BeanAnimal overflow.

[Floyd R Turbo]

The caveat to that is that with a slot pipe, the end of the outflow is essentially sealed in a similar fashion, because there is not a large open area for air to intrude upwards into. The slot pipe, conveniently enough, does not allow air up in the thin gap between the slot and the screen, or at least not enough to consider it breaking the siphon. At least, this seems to be the way it appears to work. So while it is not truly a tuned siphon in the Webster's definition (or Herbie definition), I believe the functionality remains

[Amphiprion]

I'll have to experiment to see if I can replicate the same results I had before on my 75 with my particular design. It featured no standpipes, just bulkheads and fed directly to my skimmer (at the top of the skimmer). It functioned again immediately after shutting everything off (exposing the effluent to air), blasting out all the air that had made it into the tube and re-established a siphon automatically. It even functioned with the skimmer disconnected. The only thing that drove the water was the weight of a full overflow above the bulkhead and the resistance made by a ball valve below. Don't ask me why it worked, but it took a while to tune it and it functioned perfectly (and I was able to get much more than the usual 300 gph out of it, too).

Edit: If for some reason I cannot get the same results or get it to function properly, then I will likely resize the scrubber to fit the maximum flow rate the overflow can provide.

[Floyd R Turbo]

... it took a while to tune it and it functioned perfectly (and I was able to get much more than the usual 300 gph out of it, too).

Naturally

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