DIY (Interchangeable) Gravel Vacuums

Water changes.  We love ’em, we hate ’em.  When we have a fishroom running (or even in development) we desperately need a way to make ’em easier.

ball valve with barbsI have a pretty efficient setup where a single siphon hose runs out into the back yard.  There’s a siphon-starter bulb on the tank end of the hose, and there’s a shutoff valve so I can preserve the siphon as I switch from tank to tank, but there’s one huge problem:  if I’m quarantining fish for any reason, I shouldn’t be moving the hose from the quarantine/hospital tank to a healthy tank.

Add to this the constant risk of sucking a fish up into the siphon hose, and it’s pretty obvious that I need some kind of gravel vacuum attachment that I can swap out as I switch from tank to tank.

IMG_9833 (1280x853)After thinking about these issues for a while, I decided to get creative with some PVC pipe.  After installing a PVC elbow fitting on the end of my water change hose,  I cut several lengths of pipe that were appropriate for each tank — for example, for a 12-inch-high 10-gallon tank, I cut a 13-inch pipe. Each of these will be used like a gravel vacuum.

The gravel vac tubes slip into the end of the elbow fitting pretty tightly — if any air leaks in, it’s not enough to break the siphon.  They’re easy to remove, though, so I can have one gravel vac pipe per tank and swap them out as I move from tank to tank.

IMG_9830 (1280x853)IMG_9828 (1280x853)So far, so good.  Now, I need a way to make sure fish don’t get sucked up.  The obvious solution is to zip-tie a piece of quilt batting “filter floss” over the mouth of each tube.  With that in mind, I used a Dremel rotary tool to cut a shallow groove around each pipe near the bottom end.  This will give zip ties a place to grip the smooth PVC.

With one pipe — the one destined for use in my gammarus shrimp tank — I cut additional holes above the bottom end and added a second groove above those.  The idea here is to reduce the strength of the suction coming from the end of the PVC tube.  I’ve seen shrimp actually get sucked right through the floss before, and obviously I want to minimize how often that happens.  I folded a longer piece of floss over the end of the pipe, covering all holes, and zip-tied it in both grooves to hold it secure.  (Side note:  I used different colors of zip ties to color-code which tube goes with each tank.)

IMG_9832 (1280x853)After snipping all the zip ties short, I gave them a trial run.  They worked — I wasn’t worried about that — and changing them out wasn’t difficult, but the best results came from the shrimp tank’s tube.  Several times during the water change, I saw shrimp swim right past the openings in the pipe.  They usually swerved as the current caught them, but they’d do a course correction and continue on their way.  I couldn’t tell that any of them were slurped up and flushed outside.  Awesome.  


It’s hard — I want to say “impossible,” but that’s not quite true — to do a good cost estimate for this project.  I used the following materials for each tube:

  • 2 short zip ties (1 longer zip tie would be fine)
    • 4 zip ties for the shrimp tank tube
  • 2-inch square of quilt batting
    • 2-inch by 6-inch (approximate) rectangle for the shrimp tank tube
  • 3/4-inch (internal diameter) PVC pipe, length depending on tank size

The zip ties come in various colors and in very large packs — often 100 or more for just a few bucks — so cost is almost negligible.  The quilt batting is really cheap, and 4 square inches costs practically nothing.  PVC pipe tends to be very inexpensive as well — currently, Home Depot’s website lists 10-foot lengths of 3/4-inch pipe for $2.39.

In short, with a few bucks of vinyl hose, a cheap siphon starter, an elbow fitting, and a PVC-to-hose barb, you can make multiple water changers at far lower cost than buying individual gravel vacuums at the pet store.  The first gravel vac will probably come out a bit more expensive than its ready-made equivalent, but after that, the low cost per tube more than makes up for it.

I hope this is a helpful article for those of you with multiple tanks!