So, in Part 1, we started putting together our small-scale Carlson Surge Device for your home reef tank. We started testing it, and now we're going to finish and get the device where it needs to be--next to and above your display tank.

At the end of the article are two videos that will help you to visualize what's happening during the testing phase.

Fit and finish

After testing in the bathtub, now we need to make this thing operational for the tank itself. We left these steps to the end, because they don't really impact the flow of the device, and the tubes and holes get in the way when tuning.


Photo is courtesy of Tim Rightnour, ©2018, All Rights Reserved.

We need to place two more holes in the bottom. One for the safety drain, and one for the input. You can put these more or less anywhere, but the safety drain needs to not interfere with the U tube in any way. You will be installing a section of 1" pipe into it, that goes almost to the top of the bucket, so if you place it inline with the U, it won't work. I elected to place my smaller input feed on the outside edge of the bucket. This way I could angle the incoming water so it swirls around inside the bucket rotating the water.

Position your bulkhead nuts, and mark them on the bucket, then cut them out with the dremel just like you did with the first one. Don't forget to use the chisel to smooth out the bottom of the bucket and remove any markings or things that will interfere with the nut going on flush.


Photo is courtesy of Tim Rightnour, ©2018, All Rights Reserved.

A half round file makes easy work of smoothing out a bad cut.

You can now install your bulkhead fittings. Remember to only hand tighten them. Put the flange side of the bulkhead, with gasket, on the inside of the bucket.


Photo is courtesy of Tim Rightnour, ©2018, All Rights Reserved.
This bulkhead is too big! This bulkhead is too small! This one is just right!

Now some of you might notice that I used a slip bulkhead here for the 1.5", as opposed to the threaded one I told you to buy. This is because I built mine from spare parts. But I want threads on it, in case I ever need to edit this thing after it's installed. To do this, I took a Schedule 80 pipe nipple, and cut it in half with my trusty Japanese saw.


Photo is courtesy of Tim Rightnour, ©2018, All Rights Reserved.

The two sides of a Japanese saw make it really easy to precisely cut tubing.

I can now glue this into the slip fitting, and convert it into a male threaded output.

At the bottom of your bucket, you should install the 1" barb fitting on the 1" bulkhead, and the 1/2" barb fitting on the 1/2" bulkhead.


Photo is courtesy of Tim Rightnour, ©2018, All Rights Reserved.

Now on the inside of the bucket, thread your 1" male to slip adapter onto the bulkhead flange, and insert a section of 1" PVC into that fitting. Mark on the pipe where you want your safety line to be, and cut. The safety line should be at least 1" from the top rim of the bucket, and at least 1" above the normal operation line of the water when the siphon activates. This way if something goes wrong, the water goes down the safety line, rather than down your wall onto the floor.


Photo is courtesy of Tim Rightnour, ©2018, All Rights Reserved.

You can now install the safety pipe and the little 1/2" L you purchased for the input feed into the bucket.


Photo is courtesy of Tim Rightnour, ©2018, All Rights Reserved.
At this point, you want to test the safety feature. We need to be sure it works properly before you rely upon it to save your floor. Take the U tube off, and take the bucket back to the tub. Use another piece of longer 1.5" pipe, or a coupling with more pipe, to extend the 1.5" pipe above the rim of the bucket. Now turn the pump back on, and make sure the water drains down the safety pipe, and never overflows. Again, I let it run for about 15 minutes, just to be sure here.


Photo is courtesy of Tim Rightnour, ©2018, All Rights Reserved.

Final assembly

Now with all the tuning and main construction done, you are ready to plumb it to the tank. You need to find it somewhere to live, up above the aquarium. In my opinion, the higher the better, but don't forget you need to be able to service it somewhat, so don't do something ridiculous.

I am not an expert when it comes to wood, so my telling you how to build a stand for this is really outside the scope of what I'm good at. What I will tell you is that I went overboard. I do not want this thing ripping off the wall and crashing down onto the floor. I built a little shelf with 2x4's and some MDF for the top, and then got massive steel wall shelf brackets rated at some absurd rating, and mounted them to studs with 4" lag bolts. I can sit on this thing, and that's important because 7 gallons times 9 lbs per gallon is 63 pounds of shifting weight.


Photo is courtesy of Tim Rightnour, ©2018, All Rights Reserved.

I then placed the bucket on the shelf, figured out where the holes needed to be drilled, and went at it with a jigsaw. Make sure that when you are done, the rim of the bucket is fully supported by the shelf, don't let the rim cross one of the holes you made. I also cut up some spare foam I had lying about, and used it to support the bottom of the bucket between the bucket and the shelf, so it didn't flex as much.

Now hook up the plumbing. Run the 1" drain to a sump or something. This will normally not do anything, but you still want it secured and in a good place, just in case. Hook your pump up to the 1/2" inlet barb, again, how you feed this thing is beyond the scope of this article, as I don't know your setup.

My setup is insane and overly complex. That being said, I feed mine with a Neptune COR15 pushing up about 8 feet from a sump with no issues. (Not even running at full power, and it also runs 2 carbon reactors). I also do NOT install any kind of anti-drainback or check valve onto the feed pump. If the pump fails or shuts down, I do not want the water sitting in the bucket, I want it to drain back down the feed line and into the sump, so the system sits dry.

Finally, we come to the hard part. We need to hook up the main surge to the tank itself. I used various lengths of 1.5" pipe here, and a variety of 45' and 90' adapters to get it into place. If you can get away with it, I really recommend the gray PVC long sweep electrical conduit, so you have a minimum of sharp bends. You could also use a reducer fitting, and run 2" pipe from the bucket to the tank, to get even better flow, but if you were going to do that, I would advise having done so from the start, and tuning in the tub with that setup.


Photo is courtesy of Tim Rightnour, ©2018, All Rights Reserved.

The water damage is from 5 years of running a Borneman surge without a lid.

The position of the outlet pipe below the waterline is pretty critical. The deeper you place it, the more back pressure on the assembly, and the higher the water has to rise in the device before it activates. If you place the pipe too low, it will never activate, and the water will overflow into the drain. The length of pipe also plays into this calculation.

Fair warning. At this point I spent 2 hours re-tuning the device. Swapping end effectors out in the aquarium side, moving the R/O tubing up and down, and was about ready to throw the whole thing out the window when I finally got it working. Absolutely go back to my checklist for how to tune it, and commit this to memory, as it will help you immensely. In the end, I even had to cut 1/4" off one of the pipes on the U tube to get it to work.

However, once I did all that, suddenly I hit the magical sweet spot. It fired repeatedly. Not only that, it has done so for days without issue, every time at the exact same spot. Success at last!

Tweaks and notes, and ideas for the future

So now I have, and maybe you have, a surge bucket running constantly on the aquarium. It's a lot of fun once the fish get used to this. Here are some final tweaks and some ideas I have for the future.

  • Install a bucket lid on it. While the Carlson device is nowhere near as splashy as the Borneman, it will still probably splash, and water + drywall = headache. Make sure you drill at least a small hole in the lid, so you don't make it air tight and have to fight air pressure, which would absolutely mess up your tuning.
  • A bonus of the lid is you can now cut a hole that is just perfect for an autofeeder to sit on. You probably want to make a little square hole, so the feeder drops into it, but sits safely on the lid with no splashes. You could also probably use some small wood or otherwise to lift it up a bit so it's not directly on the lid. Even if the feeder misses a little bit with the food, it will all be contained in the lid, so it shouldn't make a big mess.
  • I plan on printing some 3D brackets to hold a pair of float switches in the bucket. You could also probably bend some acrylic or figure out some other hack to do this. The idea is I want two. One is at the emergency level, so I know when the bucket is activating the overflow. The second is just below the fire line, so I know when the bucket is about to fire. Using this, you could do some programming with an Apex to adjust the flow of the pumps right as the device fires into the tank, or time your feeder to go off at the top of the water right before it activates.
  • Another idea would be a small food cage, that lets you drop a frozen cube into it, and sits just below the fire line. This would allow frozen food to slowly melt into the water over multiple surges, distributing food over the course of about half an hour or so. I'm thinking something like a test-tube shaped device with lots of holes at the bottom that fits into the lid. If I ever make one, I'll be sure to post to this in an article with my 3D printed design linked.
What about my ATO?

You would think this would wreak havoc with an ATO, and to some degree you might be right. It depends a lot on the volume of your system versus the volume of the surge. Initially, it will play hell with your ATO, because 5 gallons will drain out, the water level will drop, and the ATO will try to fill it back up. Then the surge will fire, and the water level will be a bit past the normal fill point, which should shut the ATO off. This cycle will equalize given a bit of time, and you will probably end up adding some water to the system. You could plan for this in advance, and add a little more salt to the system to keep the salinity from dropping as the system re-adjusts to its new water level.

It seems counter-intuitive, but your ATO will still work, it will just kind of freak out at first. The fill will remove 5 gallons from the system, which the ATO refills. You just need to be sure that your ATO line isn't near the top of your sump, and that the sump can handle potentially having 5 gallons more in it than it did when you started.

You also need to be reasonable about the size of your surge versus the total volume of your tank. If you have a 20 gallon nano, and put a 5 gallon surge on it, that is going to have some side effects. Be aware of the water levels and size appropriately. For smaller tanks, this entire procedure could be modified to use smaller diameter pipes, and maybe a 1 gallon Rubbermaid container. The process remains the same, only the scale changes.

Overall, I hope this article has been useful to you, and maybe you will end up building one of these devices. I find the operation of these devices pleasing to watch, and I feel they provide some benefit to my tank. Guests to your home will like seeing the big blast of water shoot into the tank, and it kind of gives a real ocean feel to the system. All that being said, yes, they can be noisy. If you can't hide the bucket behind a wall, it will be loud. Just be aware of this. If you build one, I'm sure your fish will thank you, and maybe even your corals.


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Author Profile: Tim Rightnour

Tim Rightnour has been keeping reef aquariums for about 20 years. During that time he has kept about 10 different tanks and spent countless hours building DIY devices to use in his reefkeeping adventures. He currently has a 125g softy tank, an 80g FOWLR, and an 800 gallon project tank.

Tim's forum name is garbled.

Note from the Editor:

Tim Rightnour deserves a special thank you for having the patience of Job explaining his surge device to me in minute detail to help me understand it and to help make his article the best it could be for everyone. Tim is a pleasure to work with.