Neptune MOS Magnetic Optical Sensor

Modern & compact magnetic water level monitoring

• Improved look, feel, and design .
• Precise water level control.
• Built-in magnetic mount.
• Silicone-encased external magnet.
• Completely waterproof.
• Compact form factor fits into tight spaces.
• Strong magnetic mount suitable for glass or acrylic up to 1/2″ thick.

The Neptune MOS replaces the previous OS-1 Optical Sensor and features an updated design that fits into tighter spaces and helps to prevent water incursion into the sensor. The MOS plugs into an Apex FMM port and uses reflected infrared light to signal your Apex when it changes state from being wet to dry or dry to wet. This sensor can be used for constructing your own ATO (auto-top-off), as a high-level warning sensor in your sump, water storage level sensor, and much more. The sensors can be mounted on any type of reservoir that has up to 1/4″ thick walls.

Warranty & Support

This product carries a 1-year manufacturer warranty on hardware from the date of purchase. Probes are consumable items and carry a 90-day warranty.

Warranty support is handled by us directly. Message our WhatsApp support with your order number and we will diagnose the fault first. Most cases are solved by replacing a single part, so you rarely need to send the whole unit. If the item does need to come back, it ships to our Delhi warehouse, and courier cost in both directions is borne by the customer. Your GST invoice is valid proof of purchase for the claim.

Backorder & Dispatch Timeline

This item is stocked to order. Back-orders are consolidated and placed with our overseas suppliers once a month, on the last day of the month, and all such orders are shipped before the 15th of the following month.

Back-orders cannot be cancelled once they have been placed with the supplier. If you cancel before that, payment-gateway charges of 2% plus GST are deducted and the balance refunded. In the rare case a supplier cannot fulfil the item, we will offer you an alternative first, and refund in full with no deduction if you would rather not take it.

Setup & Use

The MOS plugs into an FMM and uses reflected infrared light to tell the Apex when it goes from wet to dry or dry to wet. It has a built-in magnetic mount, so it holds to glass or acrylic up to 1/2 inch thick. Use it to build your own auto top-off, as a high-level alarm in a sump, or to watch a water storage level.

Returns & Replacement

Returns are accepted within 7 days of delivery, provided the item is unused and in its original packaging. Manufacturer-sealed items cannot be returned once the seal is broken, and sale-priced items are not refundable.

If your item arrives defective or damaged, message us on WhatsApp with your order number, or email us if you would rather, and we will replace it. Approved replacements are delivered within 3 to 5 business days. Transit damage is covered by insurance on every shipment. If tracking shows delivered but nothing reached you, tell us within 48 hours, which is the reporting window Indian couriers allow. Damage caused during installation or use is not covered; replacement spares for such cases are chargeable.

Full terms are on our Cancellation & Returns page.