A PAR meter is a device that measures Photosynthetically Active Radiation – the light intensity in the 400–700 nm spectrum, which corals (and their symbiotic algae) use for photosynthesis. In a reef aquarium, different corals have different light needs. Using a PAR meter allows you to quantify the light your corals receive, rather than guessing. This helps ensure you’re not giving too little light (which can cause coral starvation or browning out) or too much light (which can cause bleaching and tissue loss). Essentially, a PAR meter is a crucial tool for optimizing coral health through proper lighting. It eliminates the trial-and-error aspect of lighting adjustments; you’ll know the exact numbers and can adjust your LED or T5 intensity, photoperiod, or coral placement accordingly.

We do require a refundable security deposit when you rent the PAR meter. The deposit amount is approximately the full value of the Apogee MQ-510 unit (around $500). This is not a fee! It’s just a hold to ensure the safe return of the equipment. When you return the meter on time and in good condition, we refund the deposit in full (minus the small cost of return shipping). Think of it like a temporary charge that gets reversed. We know $500 is substantial, which is why we emphasize that it will come back to you as long as the meter comes back to us. If the meter were not returned or were returned in a heavily damaged condition, the deposit would cover the replacement or repair; however, this is a very rare situation. In normal circumstances, you’re essentially just paying the rental fee and shipping. The deposit refund is typically processed within 1–3 business days of us getting the meter back, so you won’t be out of pocket for long.

We ask that you ship the meter back by the end of your rental period (e.g., ship on Day 3 for a 3-day rental, Day 7 for a 7-day rental, etc.). If you return it late without prior arrangement, late fees will apply. Typically, we charge an additional rental fee equivalent to another rental cycle if the meter is kept past the due date. This is because someone else might be waiting to use it. That said, we understand things happen, if you realize you need an extra day or two, contact us before your rental period ends. We can often work out an extension (and will charge the corresponding additional days) so you don’t lose your deposit or incur an unplanned fee. Communication is key – we’re friendly, just let us know! If the meter is significantly late and we don’t hear from you, we may have to assume it’s not coming back, at which point the deposit would be used to replace the unit. So, bottom line: return on time or talk to us to extend. We want it to be fair for everyone.

Yes – the MQ-510 is quite user-friendly even for first-timers. In summary, you press the power button to turn it on (the LCD will light up and show a reading, likely zero if not under light). You then place the sensor where you want to measure – instantly, the number on the screen will show the PAR reading in µmol·m²·s⁻¹. It updates in real time as you move the sensor. There are only two buttons: Power and Mode. You only need Mode if you want to log readings or view memory; for basic use, you can ignore it. Important: remember the handheld portion isn’t waterproof, so don’t drop it in the tank (hold the sensor by the wand or cable to take underwater readings). The readings might jump around slightly if the sensor moves or if fish swim by; that’s normal, just try to hold it steady for a second to get a stable value. We recommend taking multiple readings around the tank and writing them down. If you can use a thermometer or any basic aquarium test kit, you can definitely use this PAR meter. And if you need help, we’re here for support during your rental.

It depends on the type of corals you keep. Different corals have different light requirements:

• Low-light corals (many soft corals, mushrooms, certain LPS): tend to thrive around 50–200 µmol/m²/sec PAR. Examples: mushrooms, zoanthids, leathers, brain corals, etc., often prefer the lower end of this range, though some can adapt higher.
• Medium-light corals (LPS and easier SPS): roughly 100–250 µmol/m²/sec is a moderate range. Many Euphyllia (hammers, frogspawn, torches) and Montipora SPS corals fall here, for instance.
• High-light corals (SPS like Acropora, clams, etc.): typically enjoy 200–400+ µmol/m²/sec. Acropora and Stylophora, for example, often color up best in the 250–350 PAR zone. Some Acropora even tolerate more than 400 in the wild, but in our tanks it’s wise to be cautious beyond 400.

These are general guidelines; every tank is different. Use the PAR meter to map your specific aquarium. You might find that the top of your rockwork under an LED cluster is 300 PAR, while the bottom corners are 50. That’s fine as long as you place corals in appropriate spots (high-light corals up top, low-light ones in those dim corners). Also note that PAR can vary throughout the day and can be higher right under the light source versus at an angle. That’s why measuring multiple points is important. If you’re unsure, aim for the middle of a coral’s known range and observe its response (open, coloration, growth). The PAR meter helps take out the mystery – you’ll know what those numbers are and can adjust your lights (intensity or height) to hit the targets. Feel free to ask us or consult references if you need specific PAR recommendations for particular species.

We understand accidents can happen. If the meter or any accessory gets damaged, please inform us as soon as possible. The general policy is that significant damage or loss may result in a corresponding deduction from your deposit to cover repair or replacement. For example, if the sensor is cracked or the unit stops functioning due to being dropped in water, the repair cost would come out of the deposit. Minor scuffs or signs of normal use are okay, but major issues (cracked screen, water ingress, missing parts) are not. We don’t want to take anyone’s deposit unnecessarily, and we will provide documentation of any charges. The best practice is to handle the equipment as if it were your own expensive device – keep it safe from falls, don’t force the connector, rinse off salt. If the device arrives to you with any issue, let us know immediately and we’ll make it right. Our goal is for every renter to have a successful experience, and that includes returning it hassle-free. So far, we’ve had an excellent track record with renters taking good care of the unit.