Shrimp Guard Sizing: How to Measure Your Filter Intake or Lily Pipe
Measure before you order a shrimp guard. A guard fits a specific outer diameter, so guessing the size means it will either not slide on or sit too loose to trust with animals you care about.
This guide covers how to measure a canister intake, how to measure a lily pipe intake, and what to do if you already ordered the wrong size. It pairs with our guide on why shrimp and fry get pulled into intakes in the first place.
Measuring your intake tube's outer diameter
A guard slides over the outside of your intake, so the number that matters is the outer diameter, not the inner one. A soft tape measure, a piece of string and a ruler, or a set of calipers all work. Calipers give the most accurate reading if you have them, since a soft tape can stretch a little under tension and read a touch small.
- Wrap the tape or string around the tube at the point where the guard will sit.
- Mark or note where it meets itself, then measure that length.
- Divide the distance around by 3.14 to get the outer diameter. A calculator on your phone handles this fine.
- Round to the nearest half millimeter and compare it to the table below.
- If your number lands between two sizes, measure again. A loose first pass is a common source of error.
| Product | Fits (sourced) | Same fitting as |
|---|---|---|
| TankRig shrimp guard | 16/22mm | Eheim Classic 600 intake and other 16/22mm canister models |
Fitting size comes from fitment-data.ts, sourced from Eheim and JBL's own spec pages. See our hose size guide for the full model list.
Measuring a lily pipe intake specifically (do not assume it is 17mm)
Hobbyists often talk about lily pipes as a 13mm or a 17mm size, but that is hobby shorthand, not a spec any single brand publishes. We do not have a verified number for a third party glass or acrylic lily pipe's outer diameter, so measure your own before you order rather than trust a number from a forum post.
If you already own a TankRig lily pipe inflow set, you do not need a separate guard. The inflow tip ships with the same slotted cage built in. This guide is for a bare canister intake, or for a lily pipe from another brand that does not already have a guard on it.
What happens if you order the wrong size
Too tight and the guard will not seat fully, or you will crack it trying to force it on. Too loose and it can work its way off over time, or leave a gap wide enough for a shrimplet to slip past.
If you are between two sizes, measure again before you order rather than guess up or down. A five minute recheck costs you nothing. A part that does not do its job costs you a lot more.
Fitting a guard without restricting flow
The slots in our guard are cut into the cage wall so water moves through easily while still blocking a shrimp or a fry sized body. We have not measured a flow rate change with the guard installed, and we are not going to publish a number we have not tested.
Push the guard on until it seats fully against the barb or fitting. A guard that is only halfway on can pinch its own opening and choke the flow more than a fully seated one would.
Frequently asked questions
What size is the TankRig shrimp guard?+
It fits a 16/22mm barb, the size used on an Eheim Classic 600 intake and several other canister models. This is sourced from our fitment data, not a guess.
How do I measure without calipers?+
Wrap a soft tape or a piece of string around the tube, mark where it meets itself, measure that length, then divide by 3.14 to get the outer diameter.
Is a lily pipe intake always 17mm?+
No. That number gets used loosely in the hobby, but it is not a published spec from any one brand. Measure your own lily pipe before you order a guard for it.
I already own a TankRig lily pipe set. Do I need a separate guard?+
No. Our lily pipe inflow set already has the same slotted cage built into the tip. A bare canister intake, or another brand's lily pipe, is what this guide is really for.
Will a guard slow down my filter?+
We have not measured a flow rate change and we do not publish numbers we have not tested. The slots are cut wide enough to pass water while still blocking shrimp and fry.
What if my measurement does not match this guard's size?+
Then it likely will not seat right. We only sell a 16/22mm guard today. Hold off on ordering until a size that matches your measurement is available, rather than force a wrong fit.
A note on safety
We print every part in PETG. It is the material aquarium keepers have used submerged for years. We cannot promise how any part performs in your tank. You know your tank and your animals best, so the call is always yours. Rinse each part in clean water before you add it to your tank.
Shop the shrimp guard
Fits a 16/22mm intake, sourced and confirmed. We print in PETG, the material aquarium keepers have used submerged for years. Made in the USA. Printed in the USA when you order.
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