Will It Fit? Aquarium Equipment Clearance Checklist

Measure the space you can use, not the cabinet’s outside

Measure between the things that will still be there once everything’s installed: baffles, hinges, braces, existing pipes and other equipment. A cabinet’s width in a catalogue doesn’t tell you how much room is left for a skimmer or filter. Note length, width and clear height, all in the same units.

Measure the cabinet opening separately. The calculator compares the space with the equipment; it can’t check whether you can get it through a door or round the pipework. Think about how it goes in and how it will come out later. Include any connections that stick out beyond the body when you measure the equipment.

Footprint and height are two separate checks

The footprint passes if the equipment’s length and width fit within the space’s length and width. Height passes if the equipment’s height plus the service clearance you entered is no more than the space available. Neither check adds a safety margin unless you build one into your measurements or clearance.

Allowing a 90-degree turn swaps length and width. It doesn’t lay an upright skimmer on its side, move its outlet or prove that cables and pipes still reach. Only allow it if the product and your setup really can sit that way.

Worked example with a turn

Take a made-up space of 20 × 30 × 50 cm and equipment measuring 25 × 15 × 40 cm. Say the instructions and your layout allow it to be turned, and you want 5 cm of clearance to service it. These are example numbers, not a real product.

Check the exact model’s manual for clearance and water depth

Red Sea’s REEFER skimmer manual lists the water depth it needs separately from the space needed above the collection cup. Its DC skimmer specs also give different heights and recommended water depths for each model. That’s why one measurement, or a product range name, can’t confirm a fit for every version.

Check the current manual for the exact item you’re buying. The water depth a skimmer needs is a different limit from your cabinet height. If you’ll use a stand to raise it to the right water level, include the stand in your height and access checks rather than assuming nothing’s changed.

Some products need to come out at a particular angle, or need space around an inlet. One extra height figure can’t describe every movement or side gap. Follow the maker’s instructions, and note any extra space the simple box check leaves out.

The checks measurements can’t answer

Confirm pipe sizes and threads, room to bend hoses, electrical ratings, ventilation, cable routes and the maker’s approved setup. Use the exact model’s instructions and what your system needs to connect up. The calculator isn’t a database of compatible products and can’t approve electrical or plumbing work.

Think about how you’ll disconnect and lift it out for maintenance. A cup you can’t reach, a trapped pump or a union you can’t get to can turn a quick clean into a full strip-down. Add any parts you’ll need for access to your budget; an adapter is an extra purchase, not proof everything will connect.

Keep a quick record before you order

Write down the model and version, where the manual came from, your measured space, the clearance needed and anything still to check. Use the checklist on the calculator page while you decide, then print it or keep your own note. Those tick boxes only last on the page; they aren’t saved or kept in the Companion.

Once you’re happy, add the purchase and running costs to the running cost planner. The Companion can attach that saved plan and record your later spending and maintenance. Keep your fit notes separately, so you can check them again when you change equipment or rearrange the cabinet.

Does a green result mean it’s definitely compatible?

No. It only checks the measurements you enter. Water depth, access, connections, installation instructions and anything else still need checking separately.

What is service clearance?

The extra room you need to remove or service a part, above its assembled height. Enter what your exact product needs, and check any other movements separately.

Can I turn the equipment round to make it fit?

The tool can swap length and width by turning it 90 degrees if you allow it. Make sure the product can sit that way; the tool doesn’t check connections or lay it on its side.