How to Make a Surge Bucket


This surge bucket was designed to provide a periodic surge of water motion in holding systems or aquariums which contain small polyp stony corals. It operates through the use of two floats which open a toilet bowl flapper. The larger float is used to power the opening of the flapper and the smaller float is used to trigger the rising of the larger float. The larger float falls to a position perpendicular to the waters surface when the bucket is emptied. It stays in this position until the water level rises high enough to raise the smaller float which is higher in the bucket. As the smaller float rises it kicks the larger float out of the perpendicular position which causes it to rise rapidly in the water column powering the rapid opening of the flapper which creates a surge of water at the output.


Surge Bucket Photos


Assembled without bucket

Assembled without bucket


Exploded without bucket

Exploded without bucket

Closed side view without bucket

Closed side view without bucket


Open side without bucket

Open side view without bucket



Closed top view

Closed top view


Open top view

Open top view


Some advantages of this surge bucket over the Carlson (Siphon) surge bucket are:


  1. It does not produce fine bubbles of air which stay suspended in the water column. When the surge first begins there is a short burst of larger bubbles which immediately rise to the surface.
  2. The surge outlet can be positioned at any level in the water and can be teed off to multiple outlets. In other words, you can have the output of the surge bucket plumbed through live rock and exit via multiple outlets pointing various directions.
  3. Plumbing considerations from the surge bucket to the tank are much simpler as there is no need to worry about a siphon break. This surge bucket simply requires a minimum amount of back pressure on the output which can be obtained by reducing the output to one inch or smaller PVC.


Materials List:

Pipe and Fittings

2 feet of ¾" PVC pipe CL200 (Thin wall)
2 ea. ¾" PVC elbow SCH 40
1 ea. ¾" PVC Coupler SCH 40
1 ea. ¾" PVC end cap SCH 40
1 ea. 1" PVC tee SCH 40
1 ea. ¾" slip to 2" slip PVC bushing
1 ea. 1" slip to 2" slip PVC bushing (Note this bushing may be changed to a ¾" to 2" bushing if you want to use ¾" pipe for the output plumbing.)
1 ea. 2" threaded to 2" slip PVC bushing
1 ea. 2" to 3" ABS coupler
1 ea. 3" thin wall ABS end cap
plumbing as needed to get water supply to the surge bucket and output to the tank.


Other items

1 ea. 5 gallon bucket
1 ea. Toilet Flush Valve (Plumb Shop part number PS 2030)
1 ea. 6" or larger all plastic cable tie
Teflon tape
1 ea. Pump 150 to 400 gph at the head to which the surge bucket will be located is recommended (Note: a smaller pump will work but it will be a long time between surges, too large of a pump will not work properly or cause an increase in bubbles.)


Assembly Notes

Dry fit all parts before gluing. You may use teflon tape in place of glue on lose joints to temporarily assemble and test the surge bucket and then glue the parts together after you are satisfied that every thing is working properly. This is highly recommended. But note that, the PVC pipe will likely slide into the fittings deeper when glue has been applied.

The ¾" PVC coupler should fit snugly into the 1" PVC tee and one side of both ¾" PVC elbows will need to slip loosely into the 1" PVC tee. Whether this will work may vary from manufacturer to manufacturer. Test these parts in the hardware store before purchasing. Here is a listing of the manufacturer and parts which I used.

1" PVC tee - Spears
¾" PVC elbow - Nibco
¾" PVC coupler Dura



1. Drill a 2 ½" hole in the bottom of the five gallon bucket, centered 2" from the side of the bucket.
2. Securely clamp the 1" tee to a work surface and Drill a ¾" hole through the center Just below the intersection of the center lines. This hole will be used as an backup overflow in case the surge fails to operate.
3. Slip the ¾" coupler over the top of the toilet flush valve overflow pipe.
4. Slip the bottom of the 1' tee over the ¾" coupler. Do Not Glue this joint even on final assembly.
5. Cut and glue a 3 ½" piece of pipe into a ¾" elbow on the end that will slip freely into the 1" tee.
6. Wrap teflon tape around the other end of the 3 ½" piece of pipe and slide it through the 1" tee and slip it into the free fitting end of other ¾" elbow. Push the pipe into the elbow as far as it can go and still allow the elbows to turn freely from the 1" tee. The pipe may be trimmed if needed. Do Not Glue these joints.
7. Cut and glue a 5 ½" piece of pipe into the open end of one of the elbows.
8. Glue the ¾" end cap onto the other end of the 5 ½" piece of pipe. This creates the small float.
9. Cut and glue a 4 ¼" piece of pipe into the remaining open end of the elbows.
10. Glue the ¾"to 2" bushing to the other end of the 4 ¼" pipe.
11. Glue the 2" to 3" coupler to the ¾" to 2" bushing.
12. Glue the 3" Thin wall end cap into the open 3" end of the 2" to 3" coupler. You will likely need to file off any lettering or mold marks on the out side of the end cap to get it to fit into the coupler. This creates the large float.
13. Put the 2" rubber washer over the threads of the flush valve with the tapered end down.
14. Place the assembled float and flush valve assembly into the bucket and slide the threaded end of the flush valve through the hole in the bottom of the bucket.
15. Secure the assembly in the bucket with the 2" nut so that the over flow pipe is as close to the side of the bucket as possible while still allowing the large float to hang straight down.
16. Wrap the threads at the bottom of the flush valve with teflon tape and screw on the 2" threaded to 2" slip bushing.
17. Glue the 2" to 1" (3/4") bushing to the open end of the 2" threaded to 2" slip bushing.
18. Grasping both PVC elbows adjust the angle of the floats to be about 45 degrees apart.
19. Using the cable tie secure the flap valve pull strap to the center of the small float (5 ½" pipe) just lose enough so that the flap is closed when the large float is in the down position.
20. Add plumbing as needed to route the output to the desired location(s).
21. Add plumbing as needed to route water supply into the surge bucket. The discharge into the bucket should be on to the side of the bucket near the bottom at an angle which reduces splash when the bucket is empty. This will reduce noise and bubbles. It should also be secured to the bucket so that it will not interfere with the moving parts. You may drill small holes at the top of the bucket to secure it with cable ties.



  • The 1" tee can be turned slightly to adjust the position that the large float falls to when in the down position. The large float should be parallel to the over flow pipe when in the down position. Use the wall of the bucket to keep it from falling past this position.
  • The level which the water rises in the bucket before surging out can be controlled with the angle between the two floats. Increase the angle to raise the water level and decrease the angle to lower the water level.
  • If the flap does not open properly you may need to increase or reduce the slack in the pull strap when in the closed position. Minor adjustments can be made by sliding the cable tie up or down the small float.


Final Notes

Check to ensure that the holes in the 1" tee are large enough to handle the overflow if the surge bucket fails. Do this while the bucket is running by holding down the large float thus preventing the bucket from surging. Then watch to see that the over flow holes can handle the volume of water entering the bucket. If not, you will need to drill additional or larger holes in the 1" tee or add a ¾" tee and elbow to the over flow pipe to create another over flow area.

For a more powerful surge raise the bucket higher above the tank. This surge devise can also be adapted to a container larger than the five gallon bucket for a longer surge.

We do not have time to help with trouble shooting problems you may have with this surge bucket.


This document was written by Devon Bolt of AquaTouch.

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Some changes in formatting were made to this document.

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How to Make a Surge Bucket